TM-9-1240-401-34-P

TELESCOPE MOUNT M146: M118A2 AND M118A3; TELESCOPE MOUNT M145: M145A1; PANORAMIC TELESCOPE: M117 AND M117A2; FIRE CONTROL QUADRANT: M15; PERISCOPE: M42

TECHNICAL MANUAL; DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE MANUAL

JULY 1993

TM-9-1240-401-34-P - Page 169 of 590

TM 9-1240-401-34&P

f. PITCH ADJUSTMENT

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2

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4

5

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10

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Install perpendicularity gage (1) or use two parallel

bars on M145/M145A1 telescope mount (2).

Level cross-leveling fixture (3) in elevation and

cross-level (ref. para

4-24a).

Set M1A1 gunner's quadrant (4) on perpen-

dicularity gage (1).

Adjust the pitch knob (5) to center the M1A1 gun-

ner’s quadrant level (6).

Engage fabricated eccentric tool (fig. C-3, appx C)

to the threaded ring (7).

Insert a common straight blade screwdriver

through center hole in fabricated eccentric tool (fig.

C-3, appx C) and engage cell (8).

Adjust cell (8) until level (9) bubble is centered

within the graduations on pitch level (9).

Hold cell (8) firmly in place while turning fabricated

eccentric tool (fig. C-3, appx C) to tighten

threaded ring (7). Be careful not to disturb the set-

ting of pitch level (9).

Mark the pitch knob (5) and bracket using tape as

an open end point for checking backlash.

Rotate pitch knob (5) one revolution clockwise and

return.

Read backlash using M1A1 gunner's quadrant (4)

by centering bubble and reading the error on the

M1A1 gunner’s quadrant (4). Backlash shall not

exceed 1 mil total. If backlash exceeds 1 mil, per-

form step 4 again.

Purge counter box assembly (ref. TM 750-116).

4-55