TM-9-2320-272-24-1

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

TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4

JUNE 1998

TM-9-2320-272-24-1 - Page 946 of 1015

TM 9-2320-272-24-1

3-207. AIR GOVERNOR MAINTENANCE (Contd)

c. Testing

NOTE

Whenever governor is tested, instrument panel primary air gauge

is used.

1.

Start engine (TM 9-2320-272-10) and allow air pressure to build to normal operating range.

NOTE

Engine speed must be adjusted to 1,275 rpm before performing

step 2.

2.

Check air pressure gauge (4) for air compressor cut-out pressure. Air governor (1) should stop

pressure buildup at 130 psi (896 kPa). If not, perform adjustment.

d. Adjustment

1.

2.

3.

4.

NOTE

Whenever governor is adjusted, instrument panel primary air

gauge is used.

Loosen locknut (2) and turn adapter (3) clockwise to raise pressure; counterclockwise to lower

pressure.

Depress brake pedal until pressure drops and air compression starts to build up pressure. Air

governor (1) should stop pressure buildup at 130 psi (896 kPa). If not, repeat step 1.

Tighten locknut (2) when correct air pressure is reached.

NOTE

After air compression cut-out pressure is adjusted, perform step 4.

Check air pressure gauge (4) for air compressor cut-in pressure by depressing brake pedal

repeatedly. Air governor (1) should stop pressure buildup above 80 psi (552 kPa). If not, replace air

governor (1).

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