TM-9-2350-311-20-2

HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5

TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR CAB, ARMAMENT, SIGHTING AND FIRE CONTROL, ELEVATING AND TRAVERSING SYSTEMS AND ASSOCIATED COMPONENTS

DECEMBER 1993

TM-9-2350-311-20-2 - Page 688 of 828

TM 9–2350–311–20–2

18–18

Change 2

18–4 M145/M145A1 TELESCOPE MOUNT: SYNCHRONIZATION AND ADJUSTMENT

This task covers:

a.

Leveling Gun Trunnions

b.

Checking Elevation Counter

c.

Checking Synchronization of M145/M145A1 Telescope Mount

d.

Adjusting Synchronization of M145/M145A1 Telescope Mount

INITIAL SETUP

Tools

Artillery and turret mechanic’s tool kit

(SC 5180–95–CL–A12)

Gun tube leveling fixture (item 2.1, Appx H)

References

TM 9–2350–311–10

DA Form 2408–4

Equipment Condition

Park vehicle on level ground (hard surface if available)

NOTE

•

The M145/M145A1 telescope mount must be synchronized whenever the M145/M145A1 tele-

scope mount or linkage assembly is changed or whenever M145/M145A1 telescope mount

may be out of synchronization.

•

The following is not the most accurate method of leveling trunnions. It is acceptable for synchro-

nizing M145/M145A1 telescope mount if an accurate M1A1 gunner’s quadrant is used and if

readings are taken with care. Instructions for more accurate plumbline method are given in

TM 9–2350–311–10.

•

Check synchronization of M145/M145A1 telescope mount (para 18–4c.). This checking proce-

dure will pinpoint the assembly requiring adjustment or synchronization.

•

Use an M1A1 gunner’s quadrant that is accurate within 0.4 mil (tested by the end-for-end meth-

od). Whenever the M1A1 gunner’s quadrant is used, the correction must be applied.

•

Frequently check the cannon tube for drift during any synchronization procedure to reduce the

chance of error due to cannon tube drift.

•

Determine breech ring correction factor (TM 9–2350–311–10).