TM-9-2320-279-20-1
M977 SERIES, 8x8 HEAVY EXPANDED MOBILITY TACTICAL TRUCKS (HEMTT)
TECHNICAL MANUAL; MAINTENANCE INSTRUCTIONS; ORGANIZATIONAL MAINTENANCE, VOLUME 1 OF 3
TM-9-2320-279-20-1 - Page 34 of 985
TM 9-2320-279-20-1
Safety and Handling
1-14. SAFETY, CARE, AND HANDLING.
a. Significant Hazards and Safety Recommendations.
Significant hazards and safety
recommendations are listed in Table 1-3.
Table 1-3. Significant Hazards and Safety Recommendation s
Operatin g
Hazar d
Safety Recommendation or Precaution
Condition¹
Low air pressure for
Do not drive vehicle while low air pressure warning
Abnormal
brakes.
buzzer is sounding or red light is on.
Vehicle instability with
Ensure that outriggers are down on firm ground, side
Abnormal
crane use.
slope does not exceed five degrees, and crane is not
overloaded.
Fire with M978 tanker.
No smoking, flames, or sparks within 50 feet (15 m).
Normal
Disconnect batteries for all electrical work.
Fuel spills with M978
Test tank automatic shutoff before bottom loading
Abnormal
tanker.
per procedure in instructions. Do not bypass
dead-man controls.
Connecting towing devices.
Do not go between vehicles until vehicles are
Normal
stopped and brakes are set.
Refueling vehicle.
Shut off engine and no smoking when filling tank.
Normal
¹Category of hazards as to whether or not they may be expected under normal or abnormal operating
conditions.
b. Cranes.
Material handling cranes for models M977, M983, M984, M984E1, M985, and M985E1 all
have overload shutdown and/or tilt warning (unstable) systems.
(1) On M983, M984, and M985E1 models a yellow caution light at fixed operator’s station and an
audible warning signal alert the operator when an unstable crane condition occurs.
(2) M983, M984, and M985E1 have an overload shutdown system which senses lift cylinder pressure
to prevent overloading the crane. The system will shut down the crane to prevent hoisting, boom
extension, or boom raising when an overload condition exists. Load lowering and boom retraction
functions will not be affected.
(3) When M977, M985, and M984E1 cranes are overloaded, the overload system will automatically
shut off power to telescope boom out, raise boom, or hoist load higher. The M977 and M984E1 overload
system, will also prevent lowering the boom. An overload condition can be corrected by lowering load to
ground or other supporting surface. All crane functions will be restored in approximately six seconds.
c. Crane Operating Instruction Plate Locations :
(1) The crane operating instruction plates are located on the heater compartment cover in the cab,
and at each of the fixed operating stations.
(2) The outrigger leg signs are located on each of the outrigger cylinders.
(3) The load capacity signs are located at the main and auxiliary control panels and on M984E1, they
are also located on the wrecker body rear stowage box doors.
Section Ill .
PRINCIPLES OF OPERATION .
Vehicle Operation Systems
1-15. POWER TRAIN.
(fig. 1-9) Power for the vehicle is provided by a diesel engine (1) which is
coupled directly to an automatic transmission (2). Power from the transmission is transferred to the
transfer case (3) and on to the front and rear axles (4) through a series of propeller shafts and universal
joints (5).
1-1 2
Back to Top
