TM 9-2320-272-24-1
1-24. HYDRAULIC SYSTEM OPERATION (Contd)
c. Dump Body Hydraulic System Operation.
The dump body is installed on M929/A1/A2 and M930/A1/A2 model vehicles. These models are used to
transport and deposit cargo. The dump body hydraulic system converts mechanical power from the engine
into fluid power through use of the hydraulic pump. The pump draws fluid from the oil reservoir and then
forces it into the control valve. This hydraulic pressure raises and lowers the dump body. Major components
of the dump body hydraulic system are:
Key Item and Function
13 TRANSMISSION PTO CONTROL - A manually-operated control lever located inside the vehicle
cab that permits engagement or disengagement of the transmission PTO.
14 TRANSMISSION PTO - Uses driving power of the transmission to provide mechanical driving
power for the hydraulic pump.
15 PTO DRIVESHAFT - Transmits mechanical driving power from the PTO to the hydraulic pump.
16 HYDRAULIC PUMP - Driven by the PTO driveshaft, it draws oil from oil reservoir through
hydraulic hoses, then pressurizes and directs it to the control valve.
17 HYDRAULIC OIL RESERVOIR - Storage tank for hydraulic oil.
18 DUMP BODY SAFETY LATCH - Hydraulically-operated in conjunction with the dump body
control lever, the safety latch locks dump body in the lowered position and releases it when the
control lever is pulled back to the raised position.
Assembly raises and lowers dump body with hydraulic oil, forcing the cylinder upward or downward.
20 OIL FILTER - Filters used or bypassed oil from the control valve before it returns to the hydraulic
oil reservoir.
2 1 CONTROL VALVE - Four-port valve accepts pressurized oil from the hydraulic pump and directs
oil pressure flow from control valve to the hydraulic cylinders. It also directs oil returning from the
hydraulic cylinders back to the hydraulic oil reservoir.
22 DUMP BODY CONTROL LEVER - An operator control that determines the hydraulic oil pressure
flow from control valve to the hydraulic cylinders. The route this oil takes will determine whether the
dump will raise or lower.
23 CONTROL LINKAGE - Connects dump body control lever inside cab to the control valve.
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