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GROUP 1 STRUCTURE AND FUNCTION
1. HYDRAULIC SYSTEM OUTLINE
The hydraulic system is a pilot operated, open center system which is supplied with flow from the
fixed displacement main hydraulic pump.
The pilot control system is a low pressure, closed center hydraulic system which is supplied with flow
from the first(Steering) pump.
The loader system components are :
Main pump
Main control valve
Lift cylinder
Tilt cylinders
Remote control valve(Pilot control valve)
Safety valve
The pilot supply unit consists of the pressure reducing valve, relief valve and accumulator.
Flow from the main hydraulic pump not used by the steering system leaves the priority valve CF port.
It flows to the inlet port plate of a mono block type main control valve through EF part of priority valve
built in main pump.
The main control valve is a tandem version spool type, open center valve which routes flow to the
boom, bucket or auxiliary cylinders(Not shown) when the respective spools are shifted.
Flow from the steering pump is routed to the pilot supply unit where the steering pump outlet pressure
is reduced to pilot circuit pressure. The pilot supply unit flow to the remote control valve.
The remote control valve routed flow to either end of each spool valve section in the main control
valve to control spool stroke.
A accumulator mounted on pilot supply unit supplies a secondary pressure source to operated
remote control valve so the boom can be lowered if the engine is off.
The return circuit for the main hydraulic system have return filter inside the hydraulic tank. The return
filter uses a filter element and a bypass valve. The bypass valve is located in the upside of filter.
S
S
ECTION 6 WORK EQUIPMENT
6-1
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