Relief Mechanism Behavior - Stopping - Kubota KX080-3 Workshop Manual

WSM KX080-3 Mechanism
2. Stopping
The hydraulic motor runs by the supply of pressure oil from the port A to C. When no pressure oil comes
from the port A, the counterbalance valve returns to the neutral position.
With the counterbalance valve in neutral, the outlet port D is blocked and the hydraulic motor keeps run-
ning by its inertial force alone. This applies a pressure at the port D. At the relief valve A , the pressure
oil out of the port D flows through the orifices b and c in the valve a into the chamber x . The pres-
sure oil in the chamber x then moves the piston d to its stroke end. During this shift, the pressure in
the chamber x does not rise. So the valve a of relief valve A is pushed open by the pressure oil at
port D. The pressure oil at port D then flows toward the low-pressure port C.
When the relief valve A is activated, the pressure at port D is controlled and the oil is supplied to the
port C, which prevents cavitation.
When the piston d has reached its stroke end, the pressure in the chamber x and that between the
orifices b and c rise, getting the valve a closed. If the shovel's system pressure is exceeded in this
case, the relief valve A gets activated to stop the hydraulic motor.
On the other hand, the piston h of relief valve B moves in the direction of arrow by the pressure oil at
port D. The oil in the chamber y goes through the orifices g and f into the port C.
(406)
(408)
(409)
(410)
(407)
Pressure oil flow blocked from port A
IV-M-104
(411)
(412)
(413)
(414)
(415)
IV Hydraulic System
(406)Orifice f
(407)Valve e
(408)Orifice g
(409)Chamber y
(410)Piston h
(411)Piston d
(412)Orifice c
(413)Orifice b
(414)Valve a
(415)Chamber x