9-12
SECTION 4. MAJOR COMPONENTS OF THE HYDRAULIC SYSTEM
1. MAIN CONTROL VALVE
1.1 GENERAL DESCRIPTION
This valve controls the lifting and lowering operation of the hydraulic cylinder.It has especially been
developed to control the working height of the implement.It consists of a feed back valve;direction
control valve,flow-control unloading valve,and holding check valve.
1.2 SPECIFICATIONS
5 cc/min below
(Fluid temp : 50℃:pressure :100Kgf.cm(1422 psi)
C-port leaks
50 liters/min(3051 cu.in)Maximum flow
250 Kgf./㎠(3556 psi)Maximum operating pressure
1.3.CONSTRUCTION
Main spool
it consists of a spool,spool head,and snap ring E and has three functions.
a. It opens and closes passages P to C and C to T and controls the passage wall area successively.
b. It converts unloading pilot pressure to C-port pressure or tank pressure
c. It turns the pilot pressure of the pilot spool on or off.
Fig.9-19
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