Magnification	Low power High power	1.5X 6.0X
True field of view	Low power High power	32 deg 8 deg

1. Place the periscope in V-blocks of the optical I-beam bench. Place it so that sufficient space remains to permit removal of the inner tube.

2. Rotate the revolving grip (26, Figure 7-21) of the left training handle assembly so that the zero line of sight graduation on the index ring (31) corresponds to the stationary index line graduation on the fixed grip (24). This places the head prism at zero line of sight and offers no obstruction for the removal of the inner tube. Check the right training handle far change of power; it should be set for low power.

3. Remove the air outlet plug (3, Figure 7-12) and open the air outlet valve (5) of the eyepiece box (11) to allow, the internal gas pressure to be released slowly.

4. Remove the five bolts (16) from the base of the eyepiece box bottom flange plate (13). These bolts are unscrewed from tapped holes

5. Remove the training handles by taking out eight hinge bracket bolts (5, Figure 7-21 and 7-22 respectively), for the left and right training handle assemblies.

6. Remove the focusing knob by taking out four lockscrews (10, Figure 4-39).

7. Remove the rayfilter housing (13, Figure 7-19) by pulling outward on both spring actuated plunger knobs (7).

8. Remove the eyepiece attachments that are secured to the anchor screw pins (8, Figure 7-12) projecting from the eyepiece box itself.

9. Follow the procedure described in Step 14 of Section 4C1 for the removal of the hoisting yoke assembly.

10. After the nitrogen pressure is released, close the air outlet valve (5) and replace the air outlet plug (3).

12. Place the special outer tube alignment guide on the outer tube over the undercut section (Figure 4-7). Using a socket wrench, secure it so that the slotted section is lined up temporarily to the rear vertical azimuth line of the outer tube. Place the eyepiece box alignment guide over the two flat side portions of the eyepiece box (11, Figure 7-12), resting it on the front flat portion. Assemble the radius clamp (Figure 4-7) from the rear side of the eyepiece box to the two bolt projections of the alignment guide, and secure the radius clamp with two wing bolts.

Check the outer tube and eyepiece box alignment guide handles to ascertain their contact (Figure 4-8). Should any separation be detected, loosen the outer tube alignment guide bolt with a socket bench and rotate its handle in contact with the eyepiece box alignment guide handle. The purpose of the outer tube and eyepiece box alignment guides is to establish correct entry and removal guidance for the radial alignment key (17, Figure 7-12) in the eyepiece box (11) with the keyway in the lower part of the outer tube (2, Figure 7-2).

13. Remove the two lockscrews (21, Figure 7-12) in the main coupling (12) at the eyepiece box (11). The main coupling (12) is unscrewed by using a spanner wrench with an extension handle. Unscrew the main coupling counterclockwise, as it has right-hand threads for the outer tube and left-hand threads for the eyepiece box.

14. Follow the procedure outlined in Steps 18 and 19 of Section 4C1, for the detachment of special fixtures required in the removal of the inner tube.

15. Slowly pull the inner tube sections out of the outer tube until the third inner tube section (1, Figure 7-10) is clear of the outer tube.

The inner tube should be guided parallel with the outer tube and properly centered in it.

16. Place the adjustable roller stand (Figure 4-11) under the eyepiece box (11, Figure 7-12), removing the hook of the chain hoist and the shackle.

18. Connect the upper part of the lifting spreader bar (similar to Figure 4-13, but shorter in length) to the lifting projection of the hinged clamp. This projection slides between the center slot section of the upper end of the lifting spreader bar, and a bolt is placed through the clearance holes in the above projection and the spreader bar and secured with a locknut. The lifting plate projection slides into the center slot section of the spreader bar at the lower part, and is held in similar manner to the upper part. Place the chain hoist hook in the center pad clearance hole of the lifting spreader bar. The lifting spreader bar for this periscope is 15 inches shorter.

19. Take a light strain with the chain hoist on the lifting spreader bar, and remove the adjustable roller stand (Figure 4-11). Resume the removal of the inner tube slowly until the seventh inner tube section (79, Figure 7-6) is clear of the outer tube. The inner tube should be guided parallel to the outer tube and properly centered in it.

20. Attach and secure another hinged clamp over the seventh inner tube section (79) upper eccentric bearing and the eighth inner tube section lower end coupling (63) eccentric bearing, similar to Figure 4-14. Attach a shackle in the hole of the lifting projection of the hinged clamp, and with the chain hook placed in the shackle, take a light strain with the chain hoist.

21. Resume the removal of the inner tube slowly, checking to ascertain that it is guided parallel to the outer tube and properly centered in it.

22. Transport the inner tube to the V-blocks on the second I-beam bench. Remove both chain hoist hooks, hinged clamps, and steel lifting plate.

23. Remove the outer tube from the V-blocks on the optical I-beam bench with two chain hoists, using canvas covered galvanized wire taped slings wrapped once around the outer tube, transporting it to the periscope rack.

Ill. No.	Drawing Number	Num- ber Re- quired	Nomenclature
1	P-1475-1	1	Head window
2	P-1475-2	1	Range window
3	P-1480-1	1	Outer head
4	P-1481-1	1	Range window bezel frame
5	P-1481-2	1	Head window bezel frame
6	P-1481-3	1	Range window seat rubber gasket
7	P-1481-4	1	Head window seat rubber gasket
8	P-1481-5	1	Range window bezel frame rubber gasket
9	P-1481-6	1	Head window bezel frame rubber gasket
10	P-1506-16	14	Head window bezel frame lockscrews
11	P-1506-17	28	Range window bezel frame lockscrews

a. Outer head. The outer head (3) is made of solid forged corrosion-resisting steel. It serves as a covering for the skeleton head assembly (Figure 7-5) and is assembled to the upper part of the outer taper section (1, Figure 7-2). The lower part of the outer head has a tapered alignment support section with a straight threaded periphery of 32 threads per inch preceding it, which fits into a similar internal tapered alignment support section and threaded section in the upper part of the outer taper section.

A mixture of litharge and glycerin is used over the threads to maintain an internal gas and external water seal, thus establishing a permanent joint between the outer, head and upper part of the outer taper section.

The outer head flange is machined at an angle of 17 degrees 30', with a recess seat to carry a sealing rubber gasket (7) under a head window (1). Above the head window an additional sealing rubber gasket (9) adheres directly to the beveled edge of the head window and beveled seat in the head window bezel frame (5).

Figure 7-1. Outer head, head window, and range window assemblies.

The outer head flange has 14 proportionately spaced tapped holes for retaining the head window bezel frame (5) by means of 14 lockscrews (10) which are inserted in countersunk clearance holes in the head window bezel frame and screwed into tapped holes in the outer head flange.

Below the head window flange provision, a machined range window flange and recess seat is provided to carry a sealing rubber gasket (6) under a range window (2). Above the range window an additional sealing rubber gasket (8) adheres directly to the beveled edge of the range window and the beveled seat in the range window bezel frame (4).

The interior surface of the outer head is provided with ample clearance for light transmission, prism tilt mechanism, and change of power mechanism of the skeleton head and antenna array assemblies for transmission of the ultra-high frequencies of the electronic device.

b. Head window bezel frame and head window. 1. Head window bezel frame. The head window bezel frame (5) is made of phosphor bronze and is 5 7/32 inches in length. Its lower face has a machined irregular recess to fit on the head window (1) which has a 45 degrees angle. The 45 degrees angle of the beveled recess accommodates the head window bezel frame rubber gasket (9), which compresses to the angle of the head window (1) to form an air tight joint.

The outer flange of this bezel frame has 14 proportionately spaced countersunk clearance holes to accommodate the lockscrews (3). These lockscrews extend beyond the above countersunk clearance holes and are screwed into tapped holes in the outer head flange for the head window assembly. The upper side face of the bezel frame follows the same pattern as its sides, while the lower side is beveled inward at an angle of 17 degrees 30', thus providing ample clearance for the range window, bezel frame (4) directly below it.

The inner irregular circumference of the bezel frame is beveled at an angle of 45 degrees away from the line of contact with the glass to increase the effect of wind in clearing drops of water from the glass and to reduce the lodgement of water and deposits of salt by evaporation oil the glass near the inner circumference.

2. Head window. The head window (1) is made of one crown optical glass element with parallel surfaces, and rests in the recess seat in the outer head on a seat gasket (7). It is molded with a 45 degrees angle edge to which a bezel frame rubber gasket (9) is applied. It

c. Range window bezel frame and range window. 1. Range window bezel frame. The range window bezel frame (4) is made of phosphor bronze and is 9.675 inches in length. Its lower face has a machined irregular recess to fit on the range window (2) which has a 45 degrees angle. The 45 degrees angle of the beveled recess accommodates the range window bezel frame rubber gasket (8), which compresses to the angle of the range window (2) to form an air tight joint.

The outer flange of this bezel frame has 28 proportionately spaced countersunk clearance holes to accommodate lockscrews (11). These lockscrews extend beyond the above countersunk clearance holes, and are screwed into tapped holes in the outer head flange for the range window assembly. The upper and lower side faces follow the same pattern as its sides, with all corners rounded.

The inner irregular circumference of the bezel frame is beveled at an angle of 45 degrees away from the line of contact with the glass, for the same purpose as that described for the head window bezel frame (5).

2. Range window. The range window (2) is made of No. 774 Corning glass with parallel surfaces. It is 0.630 inch thick with an accuracy of 0.002 inch, and fits into the recess seat in the range window assembly flange of the outer head on a seat gasket (6). It is molded with a 45 degrees angle edge to which a bezel frame rubber gasket (8) is applied. In some periscopes this window has been left in an unpolished condition to reduce reflection from sunlight.

The distance between the inner face of the range window and the antenna array must have a clearance of 0.612 inch plus or minus 0.031 inch. Any substitution for No. 774 Corning glass in the window will radically change performance, as likewise will any chipping of the silvered or copper plated surfaces.

d. Outer taper section. The outer taper section (1, Figure 7-2) is made of solid forged corrosion resisting steel material, and has an over-all length of 5 feet 9.500 inches. It forms

The lower part of the outer taper section is provided with a tapered alignment support section with a straight threaded periphery of 12 threads per inch preceding it which fits into a similar internal tapered alignment support section and threaded section in the upper part of the outer tube (2). A mixture of litharge and glycerine is used over the threads to maintain an internal gas and external water seal, thus establishing a permanent joint between the outer taper section and the outer tube.

The inside diameter of the outer taper section does not vary from its calculated diameter at any point by plus 0.015 inch or minus 0.000 inch; and the bore of the taper is concentric within 0.005-inch finished machined.

e. Outer tube. The outer tube (2, Figure 7-2) is made of solid forged corrosion-resisting steel and has an over-all length of 29 feet 3.375 inches. It forms the outer body for the inner tube sections as shown in Figure 7-3. The upper part

The interior of the outer tube is bored, with the eccentric bearing flanges of the inner tube sections and their couplings having a sliding clearance. The external diameter, azimuth scale lines, and numerals are similar to the Type II periscope outer tube, except for the fact that the numerals start from 35 feet. The milled inside keyway, undercut groove, and ridge detail are also similar to the Type II periscope outer tube. The external threaded periphery has 16 right-hand threads per inch, whereas the Types II and III periscopes have 12 threads per inch.

7C2. Disassembly of the head and range window assemblies. The head window and range window assemblies are disassembled in the following manner:

1. Unscrew each of the 14 lockscrews (10) evenly, with several threads of each lockscrew remaining in the outer head flange face for the head window assembly (3).

3. In order to break the seal of the head window (1) and range window (2) it is necessary to apply an internal nitrogen pressure of 15 to 30 pounds in the instrument. To apply an internal nitrogen pressure requires the blanking off of the lower part of the outer tube (2, Figure 7-2) with a suitable jig and fittings for a pressure gage and a charging line.

4. After both the head window (1) and range window (2) are broken free, release the internal gas pressure, and remove the jig.

5. Remove the 14 lockscrews (10), unscrewing them from the tapped holes in the outer head flange face for the head window assembly (3).

6. Remove the head window bezel frame (5), lifting it away from the flange face of the outer head.

7. Remove the head window (1) and the head window bezel frame rubber gasket (9). The head window may stick to the head window bezel frame rubber gasket (9) and the bezel frame (5). Remove the head window bezel frame rubber gasket (9) and destroy it.

8. Remove the bead Window seat rubber gasket (7) from the recess seat in the outer head (3) and destroy it.

9. Remove the 28 lockscrews (11), unscrewing them from the tapped holes in the outer head flange face for the range window assembly (3).

10. Remove the range window bezel frame (4), lifting it away from the flange face of the outer head (3).

11. Remove the range window (2) and the range window bezel frame rubber gasket (8). The range window may stick to the range window bezel frame rubber gasket (8) and the bezel frame (4). Remove the range window bezel frame rubber gasket (8) and destroy it.

12. Remove the range window seat rubber gasket (6) from the recess seat in the outer head (3) and destroy it.

1. They should be cleaned after flooding with the use of various sized circular wire brushes and turkish toweling to remove salt deposits. They should then be blown out with filtered air.

2. Under normal conditions, turkish toweling should be used to clean out the outer head, outer taper section, and outer tube.

3. Place a canvas boot over both the outer head and the lower end of the outer tube to prevent any foreign matter from entering the cleaned outer tube, outer taper section, and outer head.

7C4. Reassembly of the head and range window assemblies. The head and range window assemblies are reassembled in the following manner.

1. Scrape the seat of the outer head for the head window if necessary, to give a true bearing surface. The head window (1) must be marked in the position its seat is scraped so that it cannot be turned end for end.

2. Place the new head window seat rubber gasket (7) of crude rubber and specified factory drawing dimensions for its insertion in the head window seat in the outer head (3).

3. The beveled seat in the head window bezel frame (5) should be scraped if necessary, to provide a true bearing surface in conjunction with, the beveled edge of the head window (1).

4. Clean the liner surface of the head window (1) with clean lens tissue and use a small air bulb to blow off any surface dust.

5. Place the head window (1) in the head window seat in the outer head (3) on the head window seat rubber gasket (7).

6. The head window bezel frame rubber gasket (9) should be approximately 1/8 inch larger than the head window outer irregular circumference, except to comply to factory drawing dimensions as to thickness. It is placed in the head window bezel frame (5) in one solid piece. Punch a small hole in the center of

7. Place the head window bezel frame (5) with the head window bezel frame rubber gasket (9) on the head window (1). Insert the four lockscrews (10) in countersunk clearance holes in the bezel frame and screw them in the tapped holes in the flange face of the outer head. Each lockscrew is screwed down flush with the head window bezel frame.

8. A flat wooden block 1 inch thick and slightly smaller than the inner circumference of the head window bezel frame (5) is placed on the head window bezel frame rubber gasket (9). Place a C-clamp over the wooden block and the outer head to flatten the raised center portion of the rubber gasket. Use a wooden wedge on the opposite side of the outer head to tighten the C-clamp evenly. The flattening of the rubber gasket forces its outer edges to adhere to the inner beveled walls in the head window bezel frame (5), and utilizes the entire area of the beveled surface in the bezel frame to maintain the seal.

9. Lubricate the 14 lockscrews (10) lightly with a medium grease before insertion and tighten them evenly. Each lockscrew is taken down equally in a series of all around adjustments, and a feeler gage is used as a check around the head window bezel frame (5). The bezel frame is tightened down to a snug setting of all lockscrews about 0.040. inch. It is desirable to maintain a .0.007-inch to 0.010-inch clearance between the bottom face of the head window bezel frame (5) and the flange face of the outer head (3). Remove the C-clamp and wooden block.

10. It is desirable to wet the head window bezel frame rubber gasket (9) thereby offering a lubricant for a brass knife edge when cutting the crude rubber gasket around the inner irregular circumference of the head window bezel frame (5). The brass knife edge will not scratch the head window surface.

11. Scrape the range window seat in the outer head (3), if necessary, to give a true bearing surface. The range window (2) must be marked in the position its seat is scraped so that it cannot be turned end for end.

13. The beveled seat in the range window bezel frame (4) should be scraped if necessary, to provide a true bearing surface in conjunction with the beveled edge on the range window (2).

14. Clean the inner surface of the range window (2) in the same manner as described for the head window (1) under Step 4 of this section. The range window should be silvered and copper plated on three surfaces; namely, the beveled edge, the outer irregular circumference, and the bottom face in contact with the seat gasket. The silvered and copper plating of the range window wherever it contacts the metal seat of the outer head eliminates the possibility of a fluctuation in the standing wave ratio of the antenna system, should water become lodged between the window and its seat in the outer head. However, its most important function is to insure that there is no RF leakage through the crack between the range window bezel frame (4) and the range window seat in the outer head (3).

15. Place the range window (2) in the range window seat in the outer head (5) on the range window seat rubber gasket (6).

16. The range window bezel frame rubber gasket (8) should be of specified factory drawing dimensions as to thickness. It should be approximately 1 3/16 inch larger than the range window outer irregular circumference. It is placed in the range window bezel frame (4) in one solid piece. Punch two 3/16-inch holes in the rubber gasket to allow trapped air to escape.

17. Place the range window bezel frame (4) with the range window bezel frame rubber gasket (8) on the range window (2). Insert six lockscrews (11) in countersunk clearance holes in the bezel frame and screw them in the tapped holes in the flange of the outer head. Each lockscrew is screwed down flush with the range window bezel frame.

18. A flat wooden block 1 inch thick and slightly smaller than the inner irregular circumference of the range window bezel frame (4) is placed on the range window bezel rubber

19. Lubricate the threads of the 28 lockscrews (11) lightly with a medium grease before insertion and tighten them evenly. Each lockscrew is taken down in a series of all around adjustments, and a feeler gage is used as a check around the range window bezel frame (4) to determine whether it is tightened down evenly. The range window bezel frame is tightened down to a snug setting of all lockscrews about 0.030 to 0.035 inch with crude rubber. With a synthetic rubber gasket, the bezel frame is tightened from an even all around snug setting of all lockscrews to about 0.025 to 0.027-inch. After a hydraulic and temperature test, this type of rubber gasket will require a further tightening of all lockscrews (11) about 3/4 to a full turn. However, this condition does not exist with crude rubber.

20. It is not desirable to wet the range window rubber gasket while using synthetic rubber material; however, it is desirable to wet the crude rubber gasket. This offers a lubricant for a brass knife edge when cutting the rubber gasket around the inner irregular circumference of the range window bezel frame (4). The brass blade will not scratch the range window surface.

21. If the outer surface of the range window has been polished and the window has not been painted, a thin coat of black aircraft enamel, type AL-E-7, should be applied by spraying. This is to reduce specular reflection of the sun from the window. IMPORTANT: Use only the paint designated. Any other paint will

7C5. Inner tube assemblies. Figure 7-3 shows the inner tube of the periscope divided into telescope systems. Each telescope system is made up of assemblies as follows:

A. Galilean telescope system.
1. Skeleton head assembly.
2. Antenna array and taper section assembly,

B. Upper main telescope system.
1. Part I. First, second, third, fourth, and fifth reduced tube sections and seventh and eighth inner tube sections.
2. Part II. Fourth, fifth, and sixth inner tube sections.

C. Lower main telescope system.
1. Part I. First, second, and third inner tube sections.
2. Part II. Eyepiece skeleton assembly.

a. Part II.	Eyepiece box and miscellaneous assemblies.
b. " "	Four packing gland assemblies.
c. " "	Eyepiece window assembly.
d. " "	Bottom plug assembly.
e. " "	Focusing knob assembly.
f. " "	Rayfilter housing and plate assembly.
g. " "	Rayfilter, eyebuffer, blinder, and stowage case assemblies.
h. " "	Variable density polaroid filter assembly.
i. " "	Training handle assemblies.
j. " "	Hoisting yoke assembly (electric and hydraulic).

1. Remove the 12 bottom plug window housing lockscrews (7, Figure 7-17) from the bottom face in the bottom plug housing (1). These

2. Attach a special square plate jig (Figure 7-4) to the face of the bottom plug clamp ring (2, Figure 7-17) with coinciding clearance

3. Tap the handle part of the special square plate jig, thereby loosening and pulling out the bottom plug assembly from the counterbored recess seat in the eyepiece box base. Remove the bottom plug housing rubber gasket (3, Figure 7-17), and destroy it.

4. Remove the 10 pressure gage assembly lockscrews (18, Figure 7-12), removing the pressure gage assembly (10).

5. Remove the four short and eight long eyepiece window frame lockscrews (2, and 3, Figure 4-38) removing the eyepiece window assembly.

6. Remove the eyepiece lens mount (78, Figure 7-11) with the eyepiece lens (33) eyepiece lens clamp ring (15), and its lockscrew (70) from the eyepiece prism front retaining plate (22).

7. Remove the six lockscrews (10, Figure 7-15) from the left training handle stuffing box body (7). Place the special packing gland wrench on the square section of the training handle actuating shaft (8), using a slight sideward thrust to remove the left training handle packing gland assembly. Remove the training handle stuffing box rubber gasket (3). 8. Remove the six 1ockscrews (10, Figure 7-16) from the right training handle stuffing box body (7). Remove the right training handle packing gland assembly in the same manner as noted in Step 7 for the left training handle packing gland assembly.

9. Remove the six lockscrews (10, Figure 7-14) from the eyepiece drive stuffing box body (8). Remove the eyepiece drive packing gland assembly in the same manner as noted in Step 7 for the left training handle packing, gland assembly. Remove the eyepiece drive stuffing box body rubber gasket (3).

10. Remove the four rayfilter drive stuffing box body lockscrews (11, Figure 7-13) from the rayfilter drive stuffing box body (6). Remove the rayfilter drive actuating gear (9) from the square section of the rayfilter drive actuating shaft (8).

11. Remove the seven lockscrews (40, Figure 7-11) from the large flange of the eyepiece skeleton (42). These lockscrews are unscrewed from tapped holes in the upper face of the eyepiece box.

12. Remove the eyepiece box (11, Figure 7-12) from the eyepiece skeleton (42, Figure 7-11), sliding it off the eyepiece skeleton.

7D2. Removal of the waveguide and air line sections. This procedure is performed in the following manner:

1. Remove the two antenna array end plate bracket lockscrews (49, Figure 7-5) from the antenna array end plate bracket (64). These lockscrews are unscrewed from tapped holes in the front face of the skeleton head (10).

2. Remove the two antenna array taper section bracket lockscrews (54) from the antenna array taper section bracket (66). These lock

Figure 7-4. Bottom plug assembly removal jig.

3. Release the two waveguide clamp plate adjustment screw lock nuts (75, Figure 7-6) and two waveguide clamp plate adjustment screws (74) to release the tension of the wave guide clamp plates (71) from the waveguide section continuation (65). These adjustment screws extend into tapped holes in the waveguide clamp bracket (73) attached to the eighth inner tube section lower end (60).

4. Release the four waveguide clamp plate adjustment screw lock nuts (14, Figure 7-7) and the four waveguide clamp plate adjustment screws (13). This releases the tension of the two waveguide clamp plates (10) from the waveguide section continuation (5). These adjustment screws extend into two tapped holes in each waveguide clamp bracket (12) attached to the sixth inner tube section (1) upper and lower ends.

5. Follow the procedure stated in Step 4, for the fifth inner tube section (19). Two waveguide clamp brackets, (30) are located at its upper and lower ends. These consist of the four waveguide clamp plate adjustment screw locknuts (32), four waveguide clamp plate adjustment screws (31), and the, two waveguide clamp plates (28) for the waveguide section continuation (23).

6. Follow the procedure stated in Step 4 for the fourth inner tube section (37). Two waveguide clamp brackets (49) are located at its up and lower ends. These consist of the four waveguide clamp plate adjustment screw locknuts, (51), four waveguide clamp plate adjustment screws (50), and the two waveguide clamp plates (47) for the waveguide section continuation (41)

7. Follows the procedure stated in Step 4 for the second inner tube section (14, Figure 7-10) waveguide clamp bracket (25), located at its upper end only. This consists of the two waveguide clamp plate adjustment screw lock nuts (27), two waveguide clamp plate adjustment screws (26), and the two waveguide clamp plate (23) for the waveguide section continuation (19).

9. Remove the waveguide clamp plate (71, Figure 7-6) and its pins (72) from the waveguide clamp bracket (73) of the eighth inner tube section (60) located at its lower end.

10. Remove the two waveguide clamp plates (10, Figure 7-7) and their pins (11) from the two waveguide clamp brackets (12) of the sixth inner tube section (1) located at its upper and lower ends.

11. Remove the two waveguide clamp plates (28) and their pins (29) from the two waveguide clamp brackets (30) of the fifth inner tube section (19) located at its upper and lower ends.

12. Remove the two waveguide clamp plates (47) and their pins (48) from the waveguide clamp brackets (49) of the fourth inner tube section (37) located at its upper and lower ends.

13. Remove the waveguide clamp plate (23, Figure 7-10) and its pins (24) from the waveguide clamp bracket (25) of the second inner tube section (14), located at its upper end only.

14. Slide the lower air line section continuations (13, 29, and 39) with the soldered air line coupling (40), through a clearance hole in and below the bottom face of the eyepiece skeleton large shoulder flange. It is carried downward sufficiently to break the air line coupling (35, Figure 7-7) joint with the center air line section continuation (34). After breaking the air line coupling joint, the lower air line section I(34) is slid upward and carried out at the disconnection point which is located in the lower part of the fifth inner tube section (19). It is carried out of the eyepiece skeleton large shoulder flange, through a clearance provision in the counterweight half (37, Figure 7-11). It is further carried through one soldered air line strap (28, Figure 7-10) located on the second inner tube section (14), four soldered air line straps (52, Figure 7-7) located on the fourth inner tube section (37), and one soldered air line strap (33) located on the fifth inner tube section (19).

15. Remove the center air line section (16) and its continuation (34) with a soldered air

16. Remove the upper air line section (19, Figure 7-6) and its continuations (27, 41, 50, 59, 77, 90, and 16, Figure 7-7) from the skeleton head (20, Figure 7-5), sliding it downward for its disconnection from the skeleton head. It is carried out of clearance holes in flanges of the reduced tube sections and the reducing coupling. It is further carried out of two soldered air line straps (76, Figure 7-6) on the eighth inner tube section (60) and one soldered air line strap (15, Figure 7-7), on the sixth inner tube section (1). The upper air line section disconnection point is located at the upper part of the sixth inner tube section.

7D3. Separation of the Galilean telescope system and fifth reduced tube section. This procedure is performed in the following manner:

1. Separate the Galilean telescope system which is located in the skeleton head assembly (Figure 7-5) from the upper flange of the fifth reduced tube section (I, Figure 7-6) in the following manner:

2. Remove the three lockscrews (42, Figure 7-5) from the left cube shifting rack (36), removing the upper end of left power shifting wire tape (35, Figure 7-11). Replace the clamp block (26, Figure 7-5) on the left tape spacer (27) and insert the lockscrews (42), screwing them into the tapped holes in the left cube shifting rack.

3. Remove the three lockscrews (43) from the right cube shifting rack (34), removing the upper end of the right power shifting wire tape (35, Figure 7-11). Replace the clamp block (26, Figure 7-5) on the right tape spacer (28) and insert the lockscrew (43) screwing them into the tapped holes in the right cube shifting rack.

4. Release the shifting wire clamp nuts (3, Figure 7-11) of both shifting wire spindle assemblies of the eyepiece skeleton assembly.

5. Elevate the head prism (1, Figure 7-5) to full elevation, which places the quadruple screw follower (3, Figure 7-6) in a suitable position, so that the head prism actuating rack (65, Figure 7-5) with its inserted dowel pins (56) has sufficient clearance for its removal from the quadruple screw follower (3, Figure 7-6). Check the position of the quadruple screw follower (3) on the quadruple screw shaft (16) so that it will be replaced in this identical position for reassembly. Remove the three lockscrews (41, Figure 7-5) from the head prism actuating rack (65). These lockscrews ate unscrewed from tapped holes in the quadruple screw follower (3, Figure 7-6).

6. Support the skeleton head assembly (Figure 7-5), while removing the six lockscrews (10, Figure 7-6) from the upper flange of the fifth reduced tube section (1). These lockscrews are unscrewed from tapped holes in the base of the skeleton head.

7. Remove the skeleton head assembly (Figure 7-5) from the upper flange of the fifth reduced tube section (1, Figure 7-6). As the skeleton head reamed alignment dowel pin hole clears the alignment dowel pin (15) projection of the fifth reduced tube section, the head prism is shifted to full depression. This is accomplished in fact, by having the head prism actuating rack (65, Figure 7-5) and dowel pins (56) engaged in the reamed holes in the quadruple screw follower (3, Figure 7-6). It is necessary to force the head prism actuating rack with its dowel pins free of the quadruple screw follower reamed holes (3). The skeleton head assembly is now free for removal from the upper flange of the fifth reduced tube section. Remove the skeleton head assembly from the fifth reduced tube section and place it to one side to prevent it from becoming damaged.

8. It is necessary to remove the skeleton head from the fifth reduced tube section, and the fifth

9. Remove the head prism drive shaft universal coupling taper pin (26) from the lower part of the head prism drive universal coupling (23) and the head prism drive shaft section (21) of the fourth reduced tube section (20).

10. Separate the fifth reduced tube section lower flange (1) from the fourth reduced tube section upper flange (20) by removing the six lockscrews (10) from the lower flange of the fifth reduced tube section (1). Unscrew these lockscrews from tapped holes in the upper flange of the fourth reduced tube section. The lower part of the head prism drive shaft universal coupling (23) slides off the undercut part of the head prism drive shaft section (21) as the fifth reduced tube section is removed. Remove the assembled fifth reduced tube section from the fourth reduced tube section.

7D4. Removal of the head prism drive shaft sections and their universal couplings. This procedure is performed in the following manner:

1. Remove the head prism drive shaft universal coupling taper pin (56, Figure 7-6), from the lower part of the head prism drive shaft universal coupling (54) of the first inner tube section (51) and the head prism drive shaft section (61) of the eighth inner tube section (60).

2. Remove the assembled head prism drive shaft, consisting of the head prism drive shaft section (21) and its shaft continuation (30) with an attached spherical bushing (49), head prism drive shaft universal coupling (45), head prism drive shaft section (43) with an attached spherical bushing (58), its shaft continuation (52), and the attached head prism drive shaft universal coupling (54), by carrying the above assembly upward. The upward movement of this assembly clears the stub section of the head prism drive shaft section (61) from the lower part of the head prism drive shaft universal coupling (54) at the lower end of the first reduced tube section (51). The assembly is then carried downward out of the clearance holes in the fourth, third, second, and first reduced tube section flanges

3. Remove the head prism drive shaft universal taper pin (36, Figure 7-10) from the upper part of the head prism drive universal coupling (34) and the stub section of the head prism drive shaft section continuation (15) and slide this shaft continuation upward sufficiently to clear the coupling.

4. Remove the head prism drive shaft section (33) and its continuation (48, Figure 7-11), sliding it upward to free it from the upper part of the head prism drive shaft universal coupling (59), carrying with it the inserted woodruff key (46). Check the position of the coupling for proper reassembly. Remove the shaft from the disconnection point located at the upper end of the first inner tube section (31, Figure 7-10) sliding it out of the elongated holes in the large and small flanges of the eyepiece skeleton and the clearance holes in the first inner tube section lower flange, carrying with it the assembled head prism drive shaft universal coupling (34).

5. Remove the head prism drive shaft section continuations (15 and 4, Figure 7-10) and its continuations (38, 20, and 2, Figure 7-7) of the head prism drive shaft section (61, Figure 7-6), from its disconnection point located at the upper part of the first inner tube section (31, Figure 7-10). The shaft section is carried downward from various clearance holes in the coupling flanges, and the head prism drive shaft guides which are attached to or part of the second, third, fourth, fifth, sixth, seventh, and eighth inner tube sections. The head prism drive shaft rubber noise eliminators are removed from the head prism drive shaft section and its continuations W the eighth, sixth, fifth, fourth, and second infer tube sections. This shaft and its continuations can also be carried upward from the first reduced tube section (51) by the inverse method.

7D5. Separation of the upper telescope system Part I from Part II. This consists of the first, second, third, fourth, fifth reduced tube sections and the seventh and eighth inner tube sections.

1. Remove the 24 lockscrews (87, Figure 7-6), from the lower part of the seventh inner

2. Remove the seventh inner tube section (79, Figure 7-6), carrying it off the upper alignment support section of the sixth inner tube section upper end coupling (4, Figure 7-7).

7D6. Separation of the upper telescope system Part If from the lower telescope system Part I. This consists of the fourth, fifth, and sixth inner tube sections.

1. Remove the 24 lockscrews (10, Figure 7-10) from the upper part of the third inner tube section (1) and the fourth inner tube section lower end coupling (40, Figure 7-7). These lockscrews are unscrewed from tapped holes in the lower alignment support section

2. Remove the fourth inner tube section (37) carrying with it the fourth inner tube section lower end coupling (40) from the upper part of the third inner tube section (1, Figure 7-10).

7D7. Separation of the lower telescope system Part I from the lower telescope system Part II, eyepiece skeleton assembly. This consists of the first, second, and third inner tube sections.

1. Remove the seven lockscrews (40, Figure 7-11) from the small flange of the eyepiece skeleton (42). These lockscrews are unscrewed from tapped holes in the lower flange of the first inner tube section (31, Figure 7-10). Remove the eyepiece skeleton assembly (Figure 7-11) from the lower flange and alignment support section of the first inner tube section (31, Figure 7-10).

Ill. No.	Drawing Number	Num- ber Re- quired	Nomenclature
1	P-1475-3	1	Head Prism
2	P-1475-4	1	Galilean eyepiece lens
3	P-1475-5	1	Galilean objective lens
4	P-1476-1	1	Galilean eyepiece lens cube
5	P-1476-2	1	Galilean objective lens cube
6	P-1476-3	1	Galilean eyepiece lens mount, housing
7	P-1476-4	1	Galilean eyepiece lens mount
8	P-1476-5	1	Galilean objective lens retainer
9	P-1476-6	3	Galilean eyepiece lens mount housing lockscrews
10	P-1441-1	1	Skeleton head
11	P-1478-1	1	Head prism mount
12	P-1478-2	1	Field prism mount lever
13	P-1478-4	2	Galilean eyepiece objective lens cube brackets (power shift side)
14	P-1478-5	1	Galilean objective lens cube bracket (prism shift side)
15	P-1478-6	1	Power shift gear bracket
16	P-1478-7	1	Head prism actuating link

a. Skeleton head frame. The skeleton head frame (10) forms the necessary framework to carry the prism tilt mechanism, Galilean telescope, and the change of power mechanism.

The prism tilt mechanism is composed of numerous mechanical parts in the upper and left side wall of the skeleton head to operate one optical element, the head prism (1).

b. Head prism. The head prism (1) is a right angle prism, made of dense flint optical glass material. It is used to reflect the light rays at right angles. The light rays enter from the horizontal and are deflected downward into the instrument. Light enters from 61 degrees elevation to 26 degrees depression in low power, and 49 degrees elevation to 14 degrees depression in high power.

c. Head prism mount. The head prism mount (11) carries the head prism (1) with a suitable clamping arrangement. Two head prism side plates left and right (23 and 25) restrict the head prism from sideward movement, and are held to the head prism mount with three lockscrews each (46). Each head, prism side plate has a head prism shade wire link (22) attached to it with a rivet (24). The opposite end of each wire link is attached to the head prism shade (20) in similar manner. Two pairs of head prism mounting clamps left and right (38 and 39) hold the head prism to its mount. Each pair of mounting clamps is held to the head prism mount with four lockscrews (44). The head prism mount is held in the skeleton head by means of a head prism mount pivot shaft (37) which is secured with two taper pins (57). The pivot shaft is secured in a bearing bracket projection looted under and a part of the head prism mount base. The pivot shaft rotates in two head prism mount pivot shaft bushings (29) inserted in opposite sides of the skeleton head (10).

d. Head prism shade. The head prism shade (20) by means of two wire links (22) moves vertically with the head prism and its mount by its insertion in opposite vertical grooves in the inner side walls of the skeleton head. It is carried with the head prism (1) and its mount for all degrees of elevation and

e. Head, prism mount lever. The head prism mount lever (12) is attached to the head prism mount pivot shaft (37) with a key (67) and a taper pin (55) to operate the pivot shaft for the elevation and the depression of the head prism (1).

g. Head prism actuating rack. The head prism actuating rack (65) is provided with two integral stops which contact a cube bracket (14) on each side, thus restricting the centerline of sight to 45 degrees elevation and 10 degrees depression. The lower part of this actuating rack is attached to a quadruple screw follower (3, Figure 7-6), by means of three lockscrews (41), and its alignment is maintained with two dowel pins (56). The actuating rack is attached to the head prism actuating link (16), by means of a link connecting shaft (18) inserted in the reamed hole in the fork section of the actuating link and the inserted bushing (17). It provides a further linkage with the actuating link for operation of the head prism mount lever (12).

h. Head prism actuating rack guide. The head prism actuating rack guide (58) has a recess slot to fit over the head prism actuating rack (65) on a head prism actuating rack guide spacer (59) and is secured to the skeleton head frame with two short and long lockscrews (52 and 53). The actuating rack guide provides a guidance for the head prism actuating rack (65).

i. Galilean eyepiece lens cube bracket. The Galilean (eyepiece lens cube bracket (19) has an integral pin projection, which serves as a pivot for the Galilean eyepiece lens cube (4) on the prism shift side. A stop is provided in its inner face to allow the cube bracket to fit over the head prism actuating link (16), thus providing a parallel guidance to the actuating link. The cube bracket is secured the skeleton head fame with two lockscrews (51).

j. Galilean objective lens cube bracket. The Galilean objective lens cube bracket (14) has an integral pin projection and serves as a pivot for the Galilean objective lens cube (5) on the prism shift side. A recess slot is provided in its inner face to fit over the head prism actuating rack (65). The cube bracket is secured to the skeleton head frame with two lockscrews (51) and provides a parallel guidance to the head prism actuating rack. It also serves as a stop in its upper and lower parts for the integral stops of the head prism actuating rack for elevation and depression of the head prism (1).

k. Galilean eyepiece lens. The Galilean eyepiece lens (2) is made of two optical elements. It consists of a divergent meniscus flint element, cemented to the equi-concave crown element, forming a negative doublet. It is mounted in a Galilean eyepiece lens mount (7) in similar manner to the Type II and III periscope with the threaded periphery of the mount moving vertically in the internal threads in the Galilean eyepiece lens mount housing (6). This vertical movement provides a means for elimination of parallax.

1. Galilean eyepiece lens mount housing. The Galilean eyepiece lens mount housing (6) is provided with an internal threaded section bore to carry the Galilean eyepiece lens mount (7) and the Galilean eyepiece lens (2). A lockscrew (50) inserted in a tapped hole in this housing secures the Galilean eyepiece lens mount after the parallax elimination. The housing is attached to the Galilean eyepiece lens cube (4) with three lockscrews (9). The housing flange has three equally spaced holes. One hole is used as a pivot hole, while the other two are elongated for collimation adjustment.

m. Galilean eyepiece lens cube. The Galilean eyepiece lens cube (4) provides a means for holding the Galilean eyepiece lens mount (7) and its housing (6). By means of integral pin projections, a part of the cube brackets (19 and 13) inserted in the reamed hole axis of this cube, the eyepiece lens cube can be rotated 90 degrees for either the IN or OUT position. The pawl holder (30) engaged in the V-grooves in the right side face of the cube, by the tension of a reinforcing spring (33), retains it in either the IN or OUT position. An elongated slot in the right side face of the cube receives an upper pin projection (68) assembled in the right cube shifting rack (34) for its actuation.

n. Galilean objective lens. The Galilean objective lens (3) is made of two optical elements.

o. Galilean objective lens cube. The Galilean objective lens cube (5) provides a means for holding the Galilean objective lens (3) in a shallow counterbored section. The outer shoulder has a threaded periphery to carry the Galilean objective lens retainer (8). By means of integral pin projections, a part of the cube brackets (14 and 13) inserted in the reamed hole axis in the cube, the objective lens cube can be rotated 90 degrees for either the IN or OUT position. The pawl holder (30) engaged in the V-grooves in the right side face of the cube retains it in either the IN or OUT position by the tension of the reinforcing spring (33). An elongated slot in the right side face of the cube receives a lower pin projection (68) assembled in the right cube shifting rack (34) for its actuation.

The change of power mechanism is located on the right side of the skeleton head frame.

p. Cube shifting racks. The tube shifting racks right and left 36) operate in vertical recess grooves in the right side wall of the skeleton head. The right cube shifting rack (34) has two assembled pin projections (68) which extend through the two elongated slots in the vertical recess groove in the right side wall of the skeleton head. The pin projections are riveted to the right cube shifting rack, and after extending through the two elongated slots, extend farther into the elongated slots in the right side faces of the Galilean eyepiece lens and the objective lens cubes (4 and 5). An integral stop is provided on each rack to contact the Galilean objective lens cube bracket (13) at the IN and OUT positions.

q. Power shifts gear. The power shift gear (35) fits between the gear teeth cut in the right and left cube shifting racks (34 and 35). The power shift gear carries the right cube shifting rack (34) to the upward position as the left cube

r. Power shift pawls. The two power shift pawls (30) are attached to the pawl holders (31) with two rivets each (32) and are secured in a vertical recess groove in the side wall of the skeleton head to the left of the left cube shifting rack (36). Each pawl holder is secured in the recess groove with two lockscrews (47). The detent section of each pawl holder extends into its individual axial slot located in this vertical recess groove to engage in their respective V-grooves in each Galilean eyepiece lens and objective lens cube (4 and 5). A reinforcing spring (33) is placed over each power shift pawl (30), and is secured into the center of the recess groove with three lockscrews (47). The reinforcing spring overlapping each power shift pawl section of the pawl holder places a constant tension on the power shift pawls, for their retention in the V-grooves.

s. Galilean eyepiece and objective lens cube brackets. The Galilean eyepiece and objective lens cube brackets (power shift side) (13) are of duplicate design. Each bracket has an integral pin projection, which serves as a pivot for the pivot hole axis in the Galilean eyepiece lens and the objective lens cubes (4 and 5) on the power shift side. Both cube brackets fit over the cube shifting racks (34 and 36) and power shift pawls and retaining spring. These brackets are secured to the flat section of the skeleton head frame with two lockscrews each (40). The Galilean objective lens cube bracket serves as a stop for the cube shifting racks (34 and 36) for the IN and OUT position of the cubes.

The Galilean telescope system in the IN position has the Galilean eyepiece and objective lenses located at the upper part of their respective cubes. When in the OUT position, both lenses are located in the rear of the skeleton head frame.

The skeleton head assembly is attached to the upper flange of the fifth reduced tube section (1, Figure 7-6) by means of a shallow counterbored alignment support section fitting on the alignment support section shoulder of the fifth reduced tube section upper flange.

t. Taper section. The taper section (62) consists of two sections of waveguide tubing (61) which are silver soldered together.

u. Antenna array assembly. The antenna array assembly (63) consists of three parts: 1) end plate bracket (64), 2) perforated antenna tubes (60), and 3) taper section assembly (62). All three parts are silver soldered together to form the antenna array assembly. The taper section (62) is silver soldered to the waveguide section (7, Figure 7-6). This assembly is secured to the skeleton head in a recess seat of similar construction milled in the front face of the skeleton head. It is secured as before mentioned in its upper and lower parts.

1. Antenna array end plate bracket. The antenna array end plate bracket (64) consists of a rectangular plate with a small rectangular projecting section. The plate section is silver soldered to the upper end of the assembled perforated antenna tubes (60). The rectangular projector extending upward is provided with two clearance holes for the insertion of the lockscrews (49). These lockscrews, when inserted, extend into tapped holes in the antenna array milled recess in the skeleton head for the securement of the upper end of the antenna array (63).

2. Perforated antenna tubes. A The two perforated sections of waveguide tubing (60) consist of two sections of waveguide tubing with six staggered rectangular perforations located in each outer face. Both sections are silver soldered together.

7E2. Disassembly. The skeleton head assembly is disassembled in the following manner:

1. Move the cube shifting racks (34 and 36), shifting the Galilean telescope system in the OUT position. This allows the Galilean eyepiece lens (2), its mount (7), and the Galilean eyepiece lens mount housing (6) to be removed. Remove the three lockscrews (9) from the flange section of the Galilean eyepiece lens mount housing (6). These lockscrews are unscrewed from the tapped holes in the face of the Galilean eyepiece lens cube (4). Scrape off the spot solder from the Galilean objective lens retainer (8) and the Galilean objective lens cube (5). Remove the Galilean objective lens (3). Release the lockscrews (50) and remove the Galilean eyepiece dens (2) and its mount (7), unscrewing it from the Galilean eyepiece lens mount housing (6). Wrap the Galilean eyepiece lens, its mount, and the Galilean objective lens separately in clean lens tissue and place to one side to prevent scratches and breakage.

2. Remove the two short and long head prism actuating rack guide lockscrews (52 and 53). Remove the head prism actuating rack guide (58) and the head prism actuating rack guide spacer (59).

3. Remove the two Galilean objective lens cube bracket lockscrews (prism shift side) (51) from the } Galilean objective lens cube bracket (prism shift side) (14). Remove the Galilean objective lens cube bracket (prism shift side) (14).

4. Remove the two Galilean eyepiece lens cube bracket lockscrews (prism shift side) (51). Remove the Galilean eyepiece lens cube bracket (prism shift side) (19).

5. Shift the head prism (1) to full elevation, in order to insert a drift punch from the rear

6. Shift the head prism to full depression and release the two head prism mount pivot shaft lockscrews (45).

7. Remove the complete assembly of the prism tilt mechanism which consists of the following from the skeleton head: head prism mount lever (12), head prism actuating link (16), link connecting shaft bushing (17), two link connecting shafts (18), head prism mount pivot shaft (37), two link connecting shaft lockscrews (48), head prism mount lever taper pin (55), head prism actuating rack (65), and the head prism mount lever key (67). The head prism mount pivot shaft (37) is carried out of the integral bearing brackets of the head prism mount and the opposite head prism mount pivot shaft bushings (29).

8. Remove the head prism mount assembly of the following: head prism (1), head prism mount (11), head prism shade (20), two head prism shade wire links (22), left and right head prism side plates (23 and 25), left and right head prism mounting clamps (38 and 39), head prism mounting clamp lockscrews (44), and the six head prism side plate lockscrews (46). The head prism shade will slide out of its opposite axial recess grooves in the inner side walls of the skeleton head, carrying it out from the upper end.

9. The prism tilt mechanism is disassembled by following Steps 9 to 12 inclusive. Release two link connecting shaft lockscrews (48) and unscrew them from the tapped holes in both ends of the head prism actuating link (16). This allows both link connecting shafts (18) to be removed.

10. Place a drift punch in each tapped hole in the end of each link connecting shaft (18) for its removal as the shafts are a snug fit to prevent lost motion. The head prism actuating rack (65) is now free of its connection in the fork section of the head prism actuating link (16). The fork section of the head prism actuating link (16) is now freed of its connection with the head prism mount lever (12).

12. Remove the head prism mount pivot shaft (37) by driving it from the head prism mount lever (12). The head prism mount lever key (67) remains in the head prism mount pivot shaft (37).

13. The head prism mount (11) and the head prism (1) are disassembled by following Steps 13 to 15 inclusive. Remove the two lockscrews (44) from the left and right head prism mounting clamps (38 and 39) at the upper end of the head prism mount (11). These lockscrews are unscrewed from tapped holes in the head prism mount. Remove the head prism (1), sliding it upward to free it of the assembled lower left and right head prism mounting clamps (38 and 39). Wrap clean lens tissue around the head prism and place it in a convenient place to prevent scratches and breakage.

14. Remove the three lockscrews (46) from the left and right head prism side plates (23 and 25), carrying with them the two head prism shade wire links (22) and the head prism shade (20). These lockscrews are unscrewed from tapped holes in each side of the head prism mount (11).

15. The lower left and right head prism mounting clamps (38 and 39) and their lockscrews (44) remain in place. This allows the head prism to be assembled into its original factory position.

16. Remove the four lockscrews (40) from the Galilean eyepiece and the objective lens cube brackets (power shift side) (13). These lockscrews are unscrewed from tapped holes in the right side wall of the skeleton head. Remove both cube brackets, raising each one equally as each bracket has an integral pin projection which extends into the skeleton head and each pivot hole axis in the Galilean eyepiece lens and the objective lens cubes (4 and 5).

17. Remove the two lockscrews (40) from the power shift gear bracket (15). These lockscrews are unscrewed from tapped holes in the right side wall of the power shift gear bracket and its integral pin projection.

19. Remove the power shift gear (35).

20. Remove the Galilean eyepiece lens and the objective lens cubes (4 and 5) from the center of each opening in the skeleton head (10).

21. Remove the three lockscrews (47) from the reinforcing spring (33) and remove the reinforcing spring.

22. Remove the two lockscrews (47) from each pawl holder (31), removing the power shift pawls and the pawl holders (30 and 31). All lockscrews for Steps 21 and 22 are unscrewed from tapped holes in the enlarged recesses in this vertical recess groove in right side wall of the skeleton head. Precautions should be taken to replace the power shift pawls and the pawl holders to their original positions.

7E3. Reassembly. The skeleton head assembly is reassembled in the following manner:

1. Place the IN and OUT position power shift pawls (30) and pawl holders (31) in the vertical recess groove in the right side wall of the skeleton head. The power shift pawls (30) fit through the axial slots in the vertical recess groove and in the V-grooves in the cubes for the IN and OUT position. Secure each pawl holder (3-1) with two lockscrews (47) which extend into tapped holes in the recess seat in the vertical recess groove located in the right side wall of the skeleton head (10).

2. Place the reinforcing spring (33) over the power shift pawls (30), securing it with three lockscrews (47). These lockscrews extend into tapped holes in the recess seat in the vertical recess groove.

3. Place the Galilean eyepiece lens and the objective lens cubes (4 and 5) in the two center openings in the skeleton-head (10), with the V-groove of the cubes fitting into the power shift pawls (30) with the Galilean telescope system in the IN position,

4. Reassemble the cube shifting racks by following the procedure of Steps 4 and 5. Apply

5. Place the left cube shifting rack (36) in the center of the three vertical recess grooves in the right side wall of the skeleton head. The left cube shifting rack (36) also operates the power shift gear (35) meshing with the gear teeth of the cube shifting rack.

6. Reassemble the Galilean eyepiece lens and the objective lens cube brackets (13) oil the flat outer surface located on the right side wall of the skeleton head over the left and right cube shifting racks (34 and 36). Check reference marks for their proper assembly. Place the pin projection of each cube bracket in the reamed hole in the skeleton head and the pivot hole axis in each cube. Carefully push the pin projection of the cube bracket down into the reamed pivot hole axis in each cube. Secure each Galilean eyepiece and objective lens cube brackets with two lockscrews (40). These lockscrews extend into tapped holes in the skeleton head right side wall.

7. Reassemble the Galilean eyepiece lens cube bracket (prism shift side) (19) on the flat outer face on the left side wall of the skeleton head. The integral pin projection is pushed into a reamed hole in the skeleton head and the pivot hole axis in the Galilean eyepiece lens cube (4). Secure the bracket with two lockscrews (51) which are inserted in countersunk clearance holes in the bracket and screwed into the tapped holes in the left side wall of the skeleton head.

8. Reassemble the Galilean objective lens cube bracket prism shift side (14) on the fiat outer face on the left side wall of the skeleton head. The integral pin projection is pushed into a reamed hole in the skeleton head and the pivot hole axis in the Galilean objective lens cube (5). Secure the bracket with two lockscrews (51) which are inserted in countersunk clearance holes in the bracket and screwed into tapped holes in the left side wall of the skeleton head.

9. Stand the skeleton head on a surface plate. With the use of a surface gage and dial

Follow the same procedure for the Galilean objective lens cube (5), measuring the front and rear sides of the upper face of the cube. Release the two lockscrews (47) and move the lower pawl holder (31) and pawl (30) axially to obtain a true horizontal measurement. Secure the two lockscrews (47) when this is accomplished.

This adjustment of the Galilean telescope mechanism is made so that upon the assembly of the lenses the optical line of sight of this system will be parallel to the optical line of sight of the remaining telescope systems. This prevents a pronounced general aberration which results when the pawl shoulders (31) and pawls (30) have a faulty alignment.

10. With the Galilean telescope system in the IN position, the left cube shifting rack (36) is placed with its integral stop against the lower side face of the Galilean objective lens cube bracket (13). In this position the power shift gear (35) is inserted in the circular recess engaging with the teeth in the right and left cube shifting racks (34 and 36). The reference mark on the gear should coincide with the reference mark on the right cube shifting rack.

11. Reassemble the power shift gear bracket (15), placing its integral pin projection in the bearing hole in the power shift gear (35), and extending it further into the reamed hole in the milled flat in the right side wall of the skeleton head. Secure the bracket with the two lockscrews (40). These lockscrews extend into tapped holes in the outer flat face on the right side wall of the skeleton head.

12. Check the movement of the Galilean telescope system in the IN and OUT position to ascertain whether the pawls engage properly. When the left cube shifting rack (36) integral stop touches the Galilean objective lens cube bracket (power shift side) (13), the V-grooves in the Galilean eyepiece dens and objective lens cubes (4 and 5), engage the power shift

13. Reassemble the head prism and mount assembly by following the procedure outlined in steps 10 to 12 inclusive: Reassemble the left and right head prism side plates (23 and 25) to their respective sides of the head prism mount (11). Secure each head prism side plate with three lockscrews (46). These lockscrews extend into tapped holes in opposite sides of the head prism mount (11).

14. Place the head prism (1) in the head prism mount (11) between both head prism side plates (23 and 25), and allow the lower face of the head prism to engage under the lower left and right head prism mounting clamps (38 and 39).

15. Attach the upper left and right head prism mounting clamps (38 and 39) with two lockscrews (44) each. These lockscrews extend into the tapped holes in the head prism mount (11).

16. Reassemble the head prism shift mechanism by following the procedure outlined in Steps 16 to 18 inclusive: Reassemble the head prism mount shaft (37) with the inserted head prism mount lever key (67) in the head mount lever (12). Insert the taper pin (55) into the head prism mount lever (12) and the head prism mount pivot shaft (37) for their securement.

17. Place the head prism mount lever (12) in the upper fork section of the head prism actuating link (16) with the thickest part of the actuating link fork section facing outward. The long section of the head prism pivot shaft (37) should face inward. Line up the holes of both the head prism mount lever (12) and the fork section of the head prism actuating link (16) for the insertion of the link connecting shaft (18). The spot face end of the link connecting shaft remains outward. Insert the link connecting shaft in the lined up holes until its lower face is flush with the lower face of the head prism actuating link (16). Insert a headless

18. Place the head prism actuating rack (65) in the lower fork section of the head prism actuating link (16). This actuating rack is placed with its integral stop projection facing outward. Line up the holes of the head prism actuating rack (65) and the fork section of the head prism actuating link (16). Insert the link connecting shaft (18) into the lined up holes, until its lower face is flush with the lower face of the head prism actuating link (16). The spot face end of the link connecting shaft (18) should remain outward. Insert a headless lockscrew (48) in a tapped hole in the side of the head prism actuating link (16). This lockscrew extends into a spot face in the link connecting shaft (18).

19. Remove the cube brackets (14 and 19) as described in paragraphs 3 and 4, Section 7E2.

20. Slide the head prism and mount assembly in the upper part of the skeleton head, sliding the head prism shade (20) downward in the opposite inner wall vertical grooves of the skeleton head (10). Lineup the holes of the head prism mount integral brackets (11) with the opposite inserted head prism mount shaft bushings (29).

21. Reassemble the prism tilt mechanism to the led side wall of the skeleton head. Place the head prism mount pivot shaft (37) in the head prism mount pivot shaft bushing (29) located in the left side wall of the skeleton head. Extend the shaft further into the head prism mount integral bracket (11) reamed holes and further into the head prism mount pivot shaft bushing (29) located in the right side wall of the skeleton head. Align the taper pin and lockscrew spot faces of the head prism mount pivot shaft (37) with the taper pin and lockscrew holes in the head prism Mount integral brackets (11). Insert the two lockscrews (5) into the tapped holes in the head prism mount integral brackets and spot faces in the head prism mount pivot shaft (37). Insert both taper pins (57) in the head prism mount integral brackets (11) and the head prism mount pivot shaft, with the head prism (1) in the depressed position.

23. Reassemble the Galilean objective lens cube bracket (prism shift side) (14) over the head prism actuating rack (65) to the flat outer face on the left side wall of the skeleton head. The integral pin projection is pushed into a reamed hole in the skeleton head and the pivot hole axis in the Galilean objective lens cube (5). Secure the bracket with two lockscrews (51) which are inserted in countersunk clearance holes in the bracket and screwed into tapped holes in the left side wall of the skeleton head.

24. Place the head prism actuating rack guide spacer (59) under the head prism actuating rack (65). Reassemble the head prism actuating rack guide (58) over the head prism actuating rack (65). Secure it in place with two short and two long lockscrews (52 and 53). These lockscrews are inserted into countersunk clearance holes in the rack guide and clearance holes in the rack guide spacer and screwed into tapped holes in the left side wall of the skeleton head.

25. Shift the Galilean telescope system to high power or the OUT position.

26. Reassemble the Galilean eyepiece lens mount housing (6) to the face of the Galilean eyepiece lens cube (4). Secure the housing with three lockscrew (4), which are inserted into clearance holes in the housing and screwed into tapped holes in the face of the Galilean eyepiece lens cube (4).

27. Clean all surface dust off both sides of the Galilean eyepiece lens (2). Reassemble the Galilean eyepiece lens with its mount (7), screwing it into the Galilean eyepiece lens mount housing (6). The Galilean eyepiece lens mount is placed in the housing with the

28. Clean the Galilean objective lens (3) using clean lens tissue. Also clean off the surface dust. Place this lens in the Galilean objective lens cube (5) with the longest radius facing downward in the IN position. Screw the Galilean objective lens retainer (8) on the threaded periphery of the Galilean objective lens cube (5). The Galilean objective lens (8) is clamped sufficiently to maintain a snug fit without any strain exerted on the lens. Apply spot solder

29. Check the Galilean telescope system and its mechanism for surface dust, using a small air bulb to blow off any surface dust and dirt. Check the head prism in similar manner.

30. Wrap the complete skeleton head assembly in clean lens tissue, until ready for its attachment to the upper flange of fifth reduced tube section (1. Figure 7-6).

Part I: First, second, third, fourth, and fifth reduced tube sections and seventh and eighth inner tube sections.

Part II: Fourth, fifth, and sixth inner tube sections.

The upper telescope system is divided principally to permit familiarization as to nomenclature, description, disassembly, and reassembly. It is composed of three lenses, namely: a positive upper eyepiece lens doublet, a plano-convex telemeter lens, and a positive upper objective lens air-space doublet. This system is used in reverse to decrease the lower telescope system to a 6-power magnification. Figure 7-6 shows the upper telescope system assembly Part I. All bubble numbers of Sections 7F1, 3, and 4, refer to Figure 7-6 unless otherwise specified.

Ill. No.	Drawing Number	Num- ber Re- quired	Nomenclature
1	P-1521-1	1	Fifth reduced tube Section
2	P-1475-6	1	Upper eyepiece lens
3	P-1478-3	1	Quadruple screw follower
4	P-1493-7	2	Quadruple screw shaft adjusting nuts
5	P-1493-8	1	Quadruple screw shaft adjusting nut washer
6	P-1495-4	1	Upper eyepiece lens clamp ring

a. Fifth reduced tube section. The fifth reduced tube section (1) is made of brass material with an over-all length of 6.870 inches: An undercut shoulder concentric with the bore projects outward from the upper and lower flanges, and forms an alignment support section to fit in a shallow counterbored alignment support section in the skeleton head, and at the lower part with the concentric bored alignment support section in the upper part of the fourth reduced tube section (20). Three bearing flanges are provided, with the outer circumference eccentric 0.125 inch from the optical centerline. The offset is necessary to provide sufficient space for the waveguide section (7) and for the optical system.

Each offset bearing flange is slotted rectangular in the thickest part, to provide a clearance space for the waveguide section. The lower and center flanges are provided with two reamed holes and counterbored recesses to accommodate, two quadruple screw aft ball bearings (8) of a push fit. The reamed holes and the counterbored recesses are located to the left of the rectangular slot. Two power shifting wire tape slots are located in each of the three flanges to the right of the rectangular waveguide slot. An axial slot and recess are provided near the center of this reduced tube section for an axial alignment screw (9) to provide sufficient movement for the upper eyepiece lens mount (18) to focus the upper eyepiece lens (2) for the removal of parallax in high power.

The upper and lower flanges are each supplied with a dowel pin (15), which reestablishes the factory alignment upon reassembly in a reamed

1. Quadruple screw shaft thrust bushing. The quadruple screw shaft thrust bushing (17) is placed on the quadruple screw shaft (16) between both quadruple screw shaft ball bearings (8). The thrust bushing serves as a distance piece between both the above ball bearing center races.

2. Quadruple screw shaft. The quadruple screw shaft (16) is machined with a quadruple right-hand thread, 20 threads per inch with a 10 degrees 30' helix angle. It engages in the internal quadruple thread in the quadruple screw follower (3). A short threaded section below the quadruple threaded section carries two adjusting nuts (4) with a straight turned stem section. The stem section extends through two quadruple screw shaft ball bearings (8) and a quadruple screw shaft thrust bushing (17) into the upper part of a head prism drive shaft universal coupling (23). The quadruple screw shaft operates the quadruple screw follower (3), moving it vertically for operation with appropriate linkage on the skeleton head for the elevation and depression of the head prism (1, Figure 7-5).

3. Quadruple screw shaft adjusting nuts. The two quadruple screw shaft adjusting nuts (4) screw vertically on the short threaded section of the quadruple screw shaft (16). The lower adjusting nut establishes the thrust elimination in the above shaft, when tightened against an adjusting nut washer (5) which contacts the upper ball bearing race (8). The upper adjusting nut serves as a locknut, preventing the lower adjusting nut from destroying the thrust setting.

4. Head prism drive shaft universal coupling. The head prism drive shaft universal coupling (23) provides a joint between the quadruple screw shaft (16) and the head prism drive shaft (21) of the fourth reduced tube

5. Thrust assembly. The thrust assembly is described as follows: The quadruple screw shaft (16) with two quadruple screw shaft adjusting nuts (4) and a quadruple screw shaft adjusting nut washer (5) are the main thrust adjusting factors. The stem section of the quadruple screw shaft extends through the center race of the upper quadruple screw shaft ball bearing (8), mounted in a counterbored recess in the center flange of the fifth reduced tube section (1). The stem section extends farther through the quadruple screw shaft thrust bushing (17) and through the center race of the lower quadruple screw shaft ball bearing (8), mounted in a counterbored recess in the lower flange of the fifth reduced tube section. The upper part of the head prism drive shaft universal coupling (23) is secured to the quadruple screw shaft with a taper pin (26), and serves as a fixed thrust collar for the shaft in its lower part.

6. Thrust principle. The thrust principle is described in the following manner: When the lower adjusting nut (4) is tightened against the adjusting nut washer (5), the quadruple screw shaft (16) is drawn upward until the upper part of the universal coupling comes into contact with the center race of the lower ball bearing (8). The thrust bushing (17) between the two center races of the upper and lower ball bearings (8) provides the necessary separation between its center races to allow the ball bearings to revolve freely without any thrust in the shaft. Both ball bearings are installed back to back so that the thrust adjustment is taken up against each upper and lower outer race thrust shoulder.

7. Quadruple screw follower. The quadruple screw follower (3) is provided with a large hub and has an internal quadruple thread to engage on the quadruple screw shaft (16). The hull is slotted and supplied with one slot spreading screw (13) and two slot closing screws (14). The slot spreading screw controls the separation of the slotted section, and the slot closing screws eliminate the lost motion of the quadruple screw follower when engaged on the quadruple screw threads of the shaft.

8. Upper eyepiece lens. The upper eyepiece lens (2) is made of two optical elements, consisting of a divergent meniscus flint element cemented to a double convex crown element, forming a positive upper eyepiece lens doublet. It is mounted in the upper eyepiece lens mount (18) and secured in the mount with a clamp ring (6). The clamp ring is provided with a lockscrew (12) to prevent its unscrewing from the mount.

9. Upper eyepiece lens mount. The upper eyepiece lens mount (18) carries the upper eyepiece lens (2) against its shoulder seat with a short threaded section to receive a threaded upper eyepiece lens clamp ring (6). The mount slides in the fifth reduced tube section (1), and it carries the upper eyepiece lens (2) axially for the removal of parallax. After final collimation, the mount is secured with two lockscrews (11) to maintain it in the adjusted position. An air channel provision is provided in the mount. Check Section A-A of the factory detail drawing. The air channel is a vertical drilled hole through the wall of the moat to provide a passage for nitrogen.

b. Fourth reduced tube section. The fourth reduced tube section (20) is made of brass material with an over-all length of 11.810-inches. An undercut shoulder projects outward from its lower flange to form an alignment support section of a sliding fit in the straight bored section in the upper part of the third reduced tube section (28). Two bearing flanges are provided, one in the upper and one in the lower part with their outer circumference

The upper flange is provided with a clearance hole located to the left of the rectangular waveguide slot for the upper part of the head prism drive shaft universal coupling (23). The lower flange has a radius cut through the flange periphery for sufficient clearance around the head prism drive shaft section (21). The upper flange is provided with six tapped holes and a reamed dowel pin hole. The upper flange of the fourth reduced tube section is secured to the lower flange of the fifth reduced tube section (1) with six lockscrews (10). The lower flange is provided with six clearance holes and an inserted dowel pin (25). The dowel pin engages in a reamed hole in the upper flange of the third reduced tube section (28) to reestablish the factory alignment upon reassembly.

The periphery of this reduced tube section tapers outward from near the upper flange, down to its lower flange. The bore is tapered in similar manner to the periphery, maintaining a uniform wall thickness. The tapered bore is provided with anti-reflection threads. The wall of this reduced tube section is tapered to provide only the necessary wall body over the marginal or oblique done of light rays diverging downward from the upper eyepiece lens (2) to the telemeter lens (29).

The head prism drive shaft section (21) is attached to the lower part of the head prism drive shaft universal coupling (23) at the upper part of this reduced tube section with a taper pin (26). No lenses are carried in the fourth reduced tube section (20). This section serves to form a partial section with the third and fifth reduced tube sections to provide the necessary focal distance between the upper eyepiece lens and the telemeter lens.

c. Third reduced tube section. The third reduced tube section (28) is made of brass material with an overall length of 13 inches. Two bearing flanges are provided, one in the upper and one in the lower part, with an eccentric offset similar to the fourth and fifth reduced tube

The upper flange has a radius cut through the flange periphery, for sufficient clearance around the head prism drive shaft section continuation (30) to the left of the rectangular waveguide slot. The lower flange is provided with a clearance hole for the same purpose, and its location is similar. The upper flange is provided with six tapped holes and a reamed dowel pin hole. The upper flange of the third reduced tube section is secured to the lower flange of the fourth reduced tube section (20) with six lockscrews (24). The lower flange is provided with six clearance holes, and an inserted dowel pin (40). The dowel pin engages in a reamed hole in the upper flange of the second reduced tube section (42) to reestablish the factory alignment upon reassembly-.

The periphery of this seduced tube section tapers outward from the upper flange, down to a shoulder. The shoulder is raised slightly and tapers outward to the lower flange. The lower part has two counterbored sections, the small counterbored section carries the telemeter lens mount (31).