Hydraulic Circuit - wsm STW37 Workshop Manual

STW34, STW37, STW40, WSM

(2) Hydraulic Circuit

The HST pump is driven by the engine output power through the clutch and the drive shaft. The oil flow volume
and its direction is controlled by operating the speed change pedal or the cruise control lever, then the output speed
and direction of the HST motor is controlled.
The HST is structured the variable displacement pump, fixed displacement motor, oil filter, charge relief valve,
neutral valve, case relief valve etc.. The oil cooler is equipped on the drain circuit.
Valve Operating Pressure
Ref. No. Valve
(2) Case Relief Valve
Check and High Pressure
(4), (5) Relief Valve
(Forward and Reverse)
(6) Charge Relief Valve
Neutral Valve
(7), (8)
(Forward and Reverse)
Oil Temperature Engine Revolution
40 to 60 °C
1500 min
104 to 140 °F
3-M3
(1) Oil Tank (Transmission
(2) Case Relief Valve
(3) Variable Displacement Pump
(4) Check and High Pressure
(5) Check and High Pressure
(6) Charge Relief Valve
(7) Neutral Valve (Forward)
(8) Neutral Valve (Reverse)
(9) Fixed Displacement Motor
(10) Oil Cooler
(11) Oil Filter
(12) Bypath Valve
A:
B:
Valve Operating Pressure
Less than
0.3 MPa (3 kgf/cm
26.4 to 29.4 MPa
(270 to 299 kgf/cm
0.4 to 0.8 MPa
-1 2
(rpm) (4 to 8 kgf/cm , 60 to 100 psi) at no-load
1.47 to 2.45 MPa
Open (15.0 to 24.9 kgf/cm
214 to 355 psi)
4.9 to 9.8 MPa
Close (50 to 99 kgf/cm
710 to 1400 psi)
TRANSMISSION
Case)
(HST Pump)
Relief Valve (Forward)
Relief Valve (Reverse)
(HST Motor)
From Power Steering
Controller
To Hydraulic Pump
2
, 40 psi) at no-load
2
, 3830 to 4260 psi)
2
,
2
,
9Y1211109TRM0003US0
KiSC issued 11, 2014 A