TM-9-2350-311-34-2
CAB, ARMAMENT, SIGHTING AND FIRE CONTROL, ELEVATING AND TRAVERSING SYSTEMS AND ASSOCIATED COMPONENTS HOWITZER, MEDIUM, SELF-PROPELLED, 155MM
TECHNICAL MANUAL; DIRECT AND GENERAL SUPPORT MAINTENANCE MANUAL
SEPTEMBER 1994
TM-9-2350-311-34-2 - Page 57 of 552
TM 9-2350-311-34-2
1-15 DIFFERENCES BETWEEN MODELS
Most of the differences among components of M109A2 and M109A3 howitzers concern the M109A3 model. There are 103
differences in the cabs of the M109A3 vehicle population. Variations among M109A2 vehicles and differences between
M109A2 and M109A3 vehicles are minimal.
M109A4 howitzers have updated hydraulic components and an added NBC system plus reliability and maintainability.
M109A5 howitzers have been updated from the M109A4 models. In addition to all M109A4 updates, the M109A5 model
also modifies the M185 cannon assembly to an M284 cannon assembly and M178 mount to an M182 mount.
The maintenance procedures in this manual will call the mechanic’s attention to any differences in cab components which
will affect the mechanic’s performance of direct and general support maintenance tasks. Where parts which must be re-
moved or inspected differ significantly in appearance, a cutaway view will be used to show the alternate parts.
Part differences not relevant to the direct and general support mechanic will not be mentioned or pictured.
Below are some examples of cab component differences important to the direct and general support mechanic.
Functional group and part
Number of Variations
How assemblies/Darts differ
00
Protective shields, race ring
3
All M109A2/M109A4/M109A5 ve-
hicles have five protective shields.
All M109A3 vehicles with three con-
tact arms have four protective
shields. All M109A3 vehicles with
five contact arms have five protec-
tive shields.
Protective shields mount on race dif-
ferently. Some M109A3 howitzers
do not have a turret shield behind
the commander’s seat.
01
Bearing assembly
2
02
Dust shield
2
02
Variable recoil assembly
Some vehicles have 212 bearing
balls mounted on 106 race ring
spacers. Other vehicles have 213
bearing balls mounted on helical
compression springs.
M109A5 howitzers have added an
extra retainer and replaced seals on
dust shield.
2
M109A5 howitzers have replaced
many seal configurations from kit
5910844 with dust boots. Also a re-
coil nut modification has been add-
ed to M109A5 vehicles.
1-37
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