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 230 of 590

TM 9-1240-401-34&P

I

5-26. M117/M117A2 PANORAMIC TELESCOPE FINAL INSPECTION AND ADJUSTMENT

- continued

I

i. AZIMUTH ERRORS (800-MlL STEPS) AND BACKLASH (AZIMUTH MECHANISM)

- continued

5

6

7

8

9

10

11

4

Again rotate azimuth knob (2) approximately one

full revolution clockwise. Rotate azimuth knob (2)

slowly counterclockwise until telescope reticle is in

coincidence with collimating projector reticle. Re-

cord readings. Be careful not to overtravel coinci-

dence point. If coincidence point is passed, repeat

this step.

Difference between readings in steps 3 and 4 is

amount of backlash and must not exceed 1.0 mil

when read on azimuth counter (3) and 1.5 mil

when read on reset counter (4).

Rotate azimuth fixture ring (1) counterclockwise to

1600 mils.

Repeat steps 2 thru 5. Azimuth counter (3) and

reset counter (4) should indicate 4800 mils.

Repeat steps 6 and 7 above, every 800 mils, until

azimuth fixture ring (1) completes two full revolu-

tions.

Replace azimuth counter (3) (ref. para 5-23) if

readings exceed tolerance in step 5.

Replace reset counter (4) (ref. para 5-23) if read-

ings exceed tolerance in step 5.

If backlash in azimuth mechanism exceeds toler-

ance, adjust plug (5) or retainer (6). Check for

binding or loose gear trains (ref. para 5-23).

5-56