TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
0003 00
HYDRAULIC SYSTEM - CONTINUED
d.
Combination Valve.
(1)
Combination valve is located under platform on right side of machine.
(2)
Combination valve is a diverter valve and a relief valve. When operator drags work tool backward, func-
tion of relief valve is for head end of tilt cylinder.
(3)
Spool in diverter valve is connected to each end of tilt cylinder. Diverter valve senses difference in pres-
sure between head end and rod end of cylinder. If difference in pressure exceeds 435 psi (3,000 kPa),
diverter valve opens and oil from head end of cylinder flows to relief valve. This can happen as operator
performs an operation which drags bucket backward. If pressure on relief valve exceeds 1,784 psi (12,300
kPa), relief valve opens and oil returns to tank.
(4)
Combination valve relieves pressure from head end of tilt cylinder in certain dump operations. Lift arms
are level. Fully dump bucket. If lift arms are raised, pressure will increase in head end of tilt cylinder until
tilt cylinder collapses. When hydraulic oil pressure exceeds 435 psi (3,000 kPa), diverter valve opens. Oil
from head end of tilt cylinder flows to relief valve. If pressure on relief valve exceeds 1,784 psi (12,300
kPa), relief valve opens and oil returns to tank.
(5)
Diverter valve keeps setting of relief valve low and diverter valve maintains high pressures during dump
operation that are needed for equalization of pressure.
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