Hyundai r35z-7 Workshop Manual page 83

(1)
Counterbalance valve work
Spring L(37)
Spring R(37)
Orifice L(40)
Orifice R(40)
Control valve
P1 P2
Spring R(31-3)
Spring L(31-3)
M1 M2
Check valve R(31-2)
Check valve L(31-2)
Motor
Plunger(31-1) Plunger notch portion
R35Z72TM05
When the fluid is supplied from pump to counterbalance valve port P1 through control valve, the
fluid flows into piston motor through check valve L (31-2), and rotate the piston motor.
On the other hand, the return fluid from the piston motor flows into the counterbalance valve
through port M2, but the fluid is interrupted by check valve R (31-2), and consequently the pump
delivery pressure will increase.
The high pressure oil at port P1 passes through orifice L (40), pushes the end of face of plunger
(31-1) and pushes the plunger rightward against spring R (37) on the opposite side with the force
proportional to the pressure.
When the hydraulic pressure rises to a certain pressure, plunger (31-1) starts moving rightward,
and the fluid in port M2 passes through the notch machined outer circular of plunger (31-1) and
flows into the port P2, producing a back pressure on the port M2, finally returning into the tank
through a control valve.
And when the pump delivery pressure rises, the throttling aperture of notch in plunger (31-1)
becomes larger, and consequently the back pressure of the port M2 becomes lower.
This way, the throttling aperture of the notch in plunger (31-1) automatically adjusts the area of a
return side passage in order to rotate the piston motor with the appropriate speed for port P1 side
flow rate (inlet flow).
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