Position Control Valve - wsm STW37 Workshop Manual

STW34, STW37, STW40, WSM

[3] POSITION CONTROL VALVE

 Lowering
1. When the position control lever is moved to the
Lowering position, the control arm (2) rotates to the
arrow. Therefore, the spool drive lever (1) moves
around the fulcrum P and push the spool (3) and
poppet 2 (4) opening the Lowering circuit.
2. When the lift arm moves downward, the feedback
arm (5) is rotated to the arrow, since the feedback
rod (6) is actuated. Therefore, the spool drive lever
(1) moves around the fulcrum Q and pull the spool
(3).
3. The lift arm stops when the spool (3) returns to the
neutral position.
(1) Spool Drive Lever
(2) Control Arm
(3) Spool
(4) Poppet 2
(5) Feedback Arm
(6) Feedback Rod
 Neutral
Pressurized oil flows at the P port, pushes open
unload poppet 1 (4) and returns to tank from T
The oil in the chamber A behind the unload poppet 1
(4) returns to the tank through the E of spool (3) and
control valve body. The oil in the hydraulic cylinder does
not flow out because the circuit is cut off by the actions
of poppet 1 (1), poppet 2 (2).
This allows the implement to be kept at a steady
height.
(1) Poppet 1
(2) Poppet 2
(3) Spool
(4) Unload Poppet 1
8-M13
HYDRAULIC SYSTEM
[3] Lowering
[4] Lowering to Neutral
P: Fulcrum
Q: Fulcrum
9Y1211109HYM0013US0
port.
1
P: Pump Port
C: Cylinder Port
T : Tank Port 1
1
E: Groove 2
A: Chamber A
9Y1211109HYM0018US0
KiSC issued 11, 2014 A