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 704 of 828

TM 9–2350–311–20–2

18–36

Change 2

18–7 M42 TANK PERISCOPE — CONTINUED

b.

Disassembly

NOTE

There are currently two production models of the M42 tank periscope in use. Early models do not

use removable charging port parts.

1

Remove two straight pins (3).

2

Remove air valve cap (5), valve core (6), purging valve stem (7) and strap (8).

3

Remove three machine screws (9), three lockwashers (10), retaining ring (11), and seal (12). Discard lock-

washers.

c.

Assembly

1

Install seal (12), retaining ring (11), three new lockwashers (10), and three machine screws (9).

2

Apply sealing compound to purging valve stem (7) threads.

3

Install strap (8), purging valve stem (7), valve core (6) and air valve cap (5).

4

Install two straight pins (3).

NOTE

Nitrogen charge was released when valve core and machine screw were removed.

5

Purge and charge (TM 750–116).

d.

Installation

1

Install M42 tank periscope (4) by inserting straight pins (3) in holes.

2

Install five new lockwashers (2) and five cap screws (1).