TM 9-2320-272-24-1
1-24. HYDRAULIC SYSTEM OPERATION (Contd)
Key Item and Function
1 TRANSFER CASE PTO CONTROL - A manually-operated control lever located inside the cab that
engages and disengages the transfer case PTO.
2 TRANSFER CASE PTO LINKAGE - Connects transfer case PTO control to transfer case PTO.
3 TRANSFER CASE PTO - Receives driving power from vehicle's engine through the transfer case to
provide mechanical driving power for the hydraulic pump.
4 PTO DRIVESHAFT - Transmits mechanical driving power from the power takeoff to the hydraulic
pump.
5 HYDRAULIC PUMP - Draws oil from hydraulic oil reservoir and directs it to valves inside the
crane control console.
6 OIL FILTER - Filters used or bypassed oil from the control valve before it returns to the hydraulic
oil reservoir.
7 HYDRAULIC OIL RESERVOIR - Storage tank for hydraulic oil.
8 SWIVEL VALVE - Permits oil to channel through pivot post while crane is swinging and eliminates
twisting of the hydraulic lines connecting reservoir to the stationary pump.
9 BOOM LIFT CYLINDER - A hydraulically-driven piston that extends upward when boom control
lever is pulled back to UP position, raising the boom. A check valve located near hydraulic oil inlet
hose prevents piston from lowering when control lever is in NEUTRAL. Oil returns through boom
control valve back to hydraulic oil reservoir allowing piston to lower when control lever is pushed
forward to DOWN position.
10 BOOM HYDRAULIC LINES - Carry the hydraulic oil to and from boom lift cylinder. Oil pumped
through the bottom lines pushes the lift cylinder piston upward. Oil pumped through the top lines
pushes the lift cylinder piston downward. When this downward action occurs, the oil that originally
pushes the cylinder upwards is returned to the hydraulic oil reservoir.
11 BOOM CONTROL LEVER - Manual control attached to the control valve that determines
hydraulic oil flow for raising and lowering action of the boom. Lever is pulled back to raise the boom
and pushed forward to lower boom.
control valves.
13 BOOM CONTROL VALVE - Located directly below boom control lever. Valve directs hydraulic oil
from the hydraulic pump to the boom lift cylinder for lifting, or out of the lift cylinder and back to the
hydraulic oil reservoir for lowering.
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