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 259 of 481
TM 9-2320-272-10
2-156.2
Change 2
2-26.1. OPERATION OF M931/A1/A2 W/O ABS AND M932/A1/A2
W/O ABS TRACTORS WHEN TOWING M131 SERIES,
M967/A1, M969/A1/A2, AND M970/A1 5,000-GALLON
FUEL TANKERS
NOTE
This paragraph is for vehicles without ABS.
a. Braking.
WARNING
• M939 series vehicles have a conventional air brake system,
which is very sensitive. Drivers of these vehicles must be
well-trained in operating tactical vehicles with air brakes.
Air brakes are unique because braking force is proportional
to pedal travel, but the driver does not experience resistance
from the brake pedal. An inexperienced driver may respond
to lack of resistance by applying too much force to brake
pedal. This may cause brakes to lock up and vehicle to
become uncontrollable, resulting in damage to vehicle or
injury or death to personnel.
• Apply brakes gradually. Panic stops may cause wheel lockup,
stalled engine, and loss of power steering. Failure to comply
may cause damage to vehicle or injury or death to personnel.
• Hard braking while turning may cause wheels to lock up and
vehicle to skid out of control, resulting in damage to vehicle
or injury or death to personnel.
• Do not drive too fast for total weight of vehicle, amount of
fuel in tanker, length and angle of grade, road conditions,
and weather. Failure to do so may result in damage to
vehicle or injury or death to personnel.
• The use of brakes on a long or steep downgrade supplements
braking effect of engine. Ensure vehicle is in correct low gear
before starting down a grade, and follow correct braking
techniques described in steps 1 through 5. Failure to comply
may result in damage to equipment or injury or death to
personnel.
• Comply with warning signs indicating length and angle of
grade. Failure to comply may result in damage to equipment
or injury or death to personnel.
• Ensure vehicle is moving 10–15 mph (16–24 km/h) slower
than posted ramp speed for entrance or exit ramps. Failure
to comply may result in vehicle rollover, causing damage to
vehicle or injury or death to personnel.
Back to Top
