6-1
1. HYDRAULIC SYSTEM OUTLINE
The loader hydraulic system is a pilot operated, closed center system which is supplied with flow
from the variable displacement piston main hydraulic pump.
The loader system components are :
·
Main pump
·
Main control valve
·
Bucket cylinder
·
Boom cylinders
·
Remote control valve (Pilot control valve, EH type)
·
Safety valve
Flow from the main hydraulic pump not used by the steering system leaves the steering valve
(EHPS) EF port.
It flows to the inlet port plate of two section or three section block type main control valve.
The main control valve is load pressure independent flow distribution system which routes flow to the
boom, bucket or auxiliary cylinders (not shown) when the respective spools are shifted.
Flow from the main pump is routed to the main control valve where pump outlet pressure is reduced
to pilot circuit pressure. The main control valve 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 safety valve 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.
SECTION 6 WORK EQUIPMENT
GROUP 1 STRUCTURE AND FUNCTION
Summary of Contents for HL955
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