Kubota WSM STa-30, Workshop Manual

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3-M3
ST
α
-30 · ST
α
-35, WSM TRANSMISSION
(2) Hydraulic Circuit
W1020746
The HST pump driven by the engine output power through the clutch and the drive shaft. It is controlled oil flow
volume and its direction by operating the speed change pedal or the cruise control lever, and the HST motor is
controlled its output speed and direction.
The HST is structured the variable displacement pump, fixed displacement motor, oil filter charge pump, charge
relief valve, neutral valve case relief valve etc.. The oil cooler is equipped on the drain circuit.
■
Valve Operating Pressure
W1014493
(1) Oil Tank (Transmission
Case)
(2) Case Relief Valve
(3) Variable Displacement
Pump (HST Pump)
(4) Charge Pump
(5) Oil Filter (10
μ
)
(6) Check and High Pressure
Relief Valve (Forward)
(7) Check and High Pressure
Relief Valve (Reverse)
(8) Charge Relief Valve
(9) Neutral Valve (Forward)
(10) Neutral Valve (Reverse)
(11) Fixed Displacement Motor
(HST Motor)
(12) Oil Cooler
(13) Oil Filter
Ref. No. Valve Oil Temperature
Engine
Revolution
Valve Operating Pressure
(2) Case Relief Valve 50 °C
122 °F 1500 rpm 0.3 MPa
Less than 3.0 kgf/cm
2
at no-load
42.7 psi
(6), (7) Check and High Pressure Relief
Valve (Forward and Reverse) 26.4 to 29.4 MPa
270 to 300 kgf/cm
2
3840.2 to 4266.9 psi
(8) Charge Relief Valve 0.4 to 0.8 MPa
4.0 to 8.0 kgf/cm
2
at no-load
56.9 to 113.8 psi
(9), (10) Neutral Valve
(Forward and Reverse) Open 1.47 to 2.45 MPa
15.0 to 25.0 kgf/cm
2
213.3 to 355.5 psi
Close 4.9 to 9.8 MPa
50 to 100 kgf/cm
2
711.2 to 1422.4 psi
KiSC issued 11, 2006 A