TM 9-2320-260-20
1-22 SPECIAL PURPOSE BODIES SYSTEMS OPERATION (Contd)
b. Dump Body Hydraulic System Operation (M817).
The M817 dump body is used to transport and deposit cargo. Dump body hydraulic system converts
mechanical power from transmission PTO into fluid power through use of hydraulic pump. Pump draws oil
from oil reservoir and then forces it into control valve. This hydraulic pressure raises and lowers dump body.
Major components of dump body hydraulic system are:
A
transmission PTO to hydraulic pump.
B
TRANSMISSION POWER TAKEOFF - Attached to side of transmission to provide power for
hydraulic pump.
DUMP BODY CONTROL LINK - Connects control valve to transmission PTO.
C
D
reservoir, then pressurizes and directs it to control valve.
E
CONTROL BOX - Transmits motion of control rod to actuate control valve.
F
CONTROL VALVE - Four-port valve accepts pressurized oil from hydraulic pump and directs oil
to cylinder assembly.
CYLINDER ASSEMBLY - Consists of two hydraulic cylinders which raise and lower dump body
G
using hydraulic oil pressure.
H
HYDRAULIC SAFETY LATCH - Hydraulically-operated in conjunction with dump body control
lever. Safety latch locks dump body in the lowered position and releases it when control lever is
raised to a vertical position.
I
DUMP BODY CONTROL ROD - Connects control lever to control box.
J
K
DUMP BODY CONTROL LEVER - Permits operation of dump body in four positions. It is
pushed forward to lowest position to raise dump body, raised to second lowest position to lock
dump body and raised to third position to lower dump body. When control lever is fully raised
to vertical position, dump body is locked in position by use of a hydraulic safety latch.
DUMP BODY CONTROL LEVER LOCK - Prevents operation of dump body control lever.
L
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