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 94 of 828
TM 9–2350–311–20–2
2–33
Section IV. GENERAL MAINTENANCE PROCEDURES
2–10 DISASSEMBLY AND ASSEMBLY PROCEDURES
A detailed removal-installation and disassembly-assembly is provided for all assemblies requiring replacement and repair.
Numbered item callouts reflect removal or disassembly sequences. Always follow the specific instructions provided in con-
nection with each maintenance procedure in Chapters 4 through 19.
NOTE
•
When troubleshooting or when working on a wiring harness or hydraulic assembly, remember
to tag wires, circuits, terminals, and hydraulic lines and fittings to make assembly easier.
•
In marking shims or other parts, use dye, indelible ink, or paint. Chalk or crayon can erase easily
and should not be used.
As a general rule, disassembly procedures instruct the mechanic to begin by removing only as many major components
and subassemblies as required for maintenance. When practical, temporarily reinstall screws, bolts, washers, and nuts to
prevent loss. Mechanics can also use a plastic storage container or plastic bags (item 4, Appx D) to sort and label parts.
In Chapters 4 through 19, assembly procedures are provided for all components requiring maintenance at the unit level.
During assembly and installation, remember to replace items discarded during removal and disassembly. Mandatory re-
placement parts include all preformed packings, non-metallic gaskets and seals, cotter pins, lockwire, and lockwashers.
These are listed in Appendix G, Mandatory Replacement Parts List.
Some tasks calling for installation of hydraulic fittings, ports in sighting equipment, gaskets, seals, and mating surfaces on
doors will instruct the mechanic to apply a specific adhesive or sealant. These adhesives and sealants are listed in Appen-
dix D, Expendable and Durable Items List.
Special care is required in handling and installing preformed packings. Damaged preformed packings can result in equip-
ment failure. When installing preformed packings, apply a light film of hydraulic fluid (item 21, Appx D) to make insertion
easier. Avoid cutting or nicking preformed packings.
When installing any hydraulic fitting, tighten the fitting to aline with the connecting lines. Repositioning can loosen fittings,
cause leaks, and damage preformed packings.
2–11 REPLACEMENT OF PARTS
2–11.1
Replacement
As a general rule, discard any part which is damaged too much to perform its function.
Mandatory replacement parts are listed in Appendix G, Mandatory Replacement Parts List.
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