TM-9-2350-311-10
HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5
TECHNICAL MANUAL; OPERATOR’S MANUAL
NOVEMBER 1994
TM-9-2350-311-10 - Page 94 of 775
TM 9-2350-311-10
2-1 OPERATOR’S CONTROLS, INDICATORS, AND INSTRUMENTS — CONTINUED
2-1.4
Crew Controls and Instruments
1
2
3
4
5
6
7
8
9
10
11
12
13
14
OPERATING HANDLE (BREECH
MECHANISM)
DOME LIGHT SWITCH
RAMMER ACTUATING VALVE
CONTROL HANDLE
FIRING MECHANISM MANUAL
CONTROL LEVER
RAMMER HANDLE
TURRET LOCK
M3 ELECTRICAL AIR HEATER
(M109A4/M109A5)
ACCESSORY CONTROL BOX
MANUAL TRAVERSE HANDWHEEL
GUNNER’S CONTROL ASSEMBLY
HANDLE
GUNNER’S SELECTOR SWITCH
BOX ASSEMBLY
EQUILIBRATION HANDPUMP
ASSEMBLY
M145/M145A1
M117/M117A2
TELESCOPE
TELESCOPE MOUNT
PANORAMIC
Allows breech to be opened manually.
Turns dome light assembly on or off.
Activates rammer actuating valve to operate rammer assem-
bly.
Movement drives firing hammer into firing pin causing primer to
ignite.
Used to move rammer in and out of ramming position.
Locks cab position to prevent cab traversing.
Four M3 electrical air heaters provide heated air to the gunner,
cannoneer no. 1, section chief, and the assistant gunner while
operating in an NBC environment.
Allows gunner to control cab ventilation and heating.
Permits manual traversing of cab.
Allows gunner to elevate, depress, and traverse cannon as-
sembly.
Controls the electrical power to the cab with the CAB POWER
switch, permits the selection of either power or manual travers-
ing mode with the TRAVERSE CONTROL switch, and controls
whether the gunner’s or assistant gunner’s control assembly
will be permitted to elevate or depress the weapon with the
ELEVATION CONTROL switch.
Used to manually increase or decrease hydraulic fluid pres-
sure.
Provides an adjustable base and support for the M117/M117A2
panoramic telescope.
Indirect fire instrument used in laying the weapon in azimuth.
2-10
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