U20-3, U25-3 WSM
Hydraulic system (Mechanism section)
3) Motor slowing down
When being slowed down, the motor keeps running for a while by its inertia force. While the coun-
terbalance valve is open, however, the hydraulic oil flows through the oil passage M2 into the port
P2.
Because there is no enough oil flow from P1, cavitation occurs at P1 and M1.
The anti-cavitation mechanism works to avoid this. Until the counterbalance valve returns to its
original state, P1 is connected with the oil passage A. In this condition, the hydraulic oil flows in
this route: oil passage M2, counterbalance throttle C, oil passage C, check valve C, oil passage A,
port P1 and oil passage M1. It finally flows back to the motor. In this way, cavitation is minimized.
IV-M-57