TM-9-2320-272-10

TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)

TECHNICAL MANUAL; OPERATOR'S MANUAL

SEPTEMBER 2004

CHANGE 2

TM-9-2320-272-10 - Page 404 of 481

TM 9-2320-272-10

3-12. AIR SYSTEM SHUTOFF VALVES

General.

Primary and secondary air systems are provided with shutoff valves to

isolate them from the rest of the vehicle air system. These valves are closed by the

operator only in an emergency situation.

(1)

The primary system air shutoff valve (1) on the M939/A1 series vehicles is

located at the forward end of the wet tank. On the M939A2 series vehicles, it is at

the side of the wet tank reservoir. If air leaks in the primary system and the vehicle

must be driven, close air shutoff valve (1). Closing the primary system air shutoff

valve (1) will isolate the primary system and maintain air pressure to brake system

components and enable operator to slow down or stop the vehicle.

(2)

The secondary system air shutoff valve (2) is located on top of the wet tank

reservoir. In the event of an air leak in the secondary system and the vehicle must

be driven, close air shutoff valve (2). Closing the secondary system and air shutoff

valve (2) will isolate the secondary system and maintain air pressure to brake

system components and enable operator to slow down or stop the vehicle.

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