TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
0003 00
HYDRAULIC SYSTEM - CONTINUED
7.
Pilot Hydraulic System.
a.
Oil for pilot circuit comes from steering pump section. Oil flows from pump. Oil flows through a manifold located
on piston pump, then through a pressure reducing valve. Oil then flows through a screen in pilot control valves.
Return oil flows back to manifold, then to tank.
b.
Component Locations.
(1)
Pilot oil pressure is located on pressure
reducing valve.
(2)
Combination valve.
(3)
Pressure reducing valve is located on
right side of machine under operator's
platform. Valve controls pressure in pilot
system.
(4)
Steering pressure test port is located on
pressure reducing valve.
c.
When a pilot control valve is moved out of
HOLD position, pilot control valve directs flow
of pilot oil to a valve spool in bank valve. This
causes valve spool to shift to allow high pressure
oil from piston pump to flow to work tools.
427-B1754
d.
Control Lever.
(1)
Standard implement hydraulic system consists of a joystick control for lift and tilt.
(2)
Joystick in lift position causes oil to flow into head end of lift cylinders to raise work tool.
(3)
Joystick in lower position causes oil to flow into rod end of lift cylinders to lower work tool.
(4)
Joystick in dump position causes oil to flow into head end of tilt cylinder to dump bucket for 924G Wheel
Loader machine.
(5)
Joystick in tilt back position causes oil to flow into rod end of tilt cylinder to tilt back bucket for 924G
Wheel Loader machine.
(6)
Switch for solenoid valve (hydraulic lockout) is used to block oil flow to pilot valves. Press top of switch.
Shutoff for pilot valve is in LOCKED position. Pilot oil to pilot control valves is blocked. This prevents
operation of implement even though operator can still move control levers.
(7)
A machine that is equipped with an implement hydraulic system with a third function has one auxiliary
control valve.
(8)
Move lever forward for third function hydraulic arrangement. This causes oil to flow into one side of aux-
iliary circuit.
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