Operation And Valves - wsm STW37 Workshop Manual

STW34, STW37, STW40, WSM

(4) Operation and Valves

Neutral Position
The pump (3) and motor (8) are joined in a closed
hydraulic loop and most of oil circulates within the main
oil circuit. A little oil lubricates and oozes out from the
clearance between the moving parts of the case.
The charge oil aids smooth operation of piston pump
(3) and motor (8). The rest of the oil passes through the
charge relief valve (5) into the case. Then the oil return
to the pump (12) through the cooler.
When the speed control pedal is in neutral, the
variable swashplate (16) is at right angles to the pump
pistons (17) and they only rotate with cylinder block (18)
without reciprocating. Since the oil is not being pumped
to the motor (8). The cylinder block (19) in the motor (8)
is stationary and the output shaft (6) does not move.
3-M5
TRANSMISSION
(1) Oil Cooler
(2) Power Steering Cylinder
(3) HST Pump
(Variable Discharge Pump)
(4) HST Oil Filter (10 µ)
(5) Charge Relief Valve
(6) Output Shaft
(7) Oil Tank
(Transmission Case)
(8) HST Motor
(Fixed Discharge Motor)
(9) Case Relief Valve
(10) Oil Filter
(11) 3P Hydraulic Pump
(12) Power Steering Pump
(13) Regulating Valve
(14) Steering Controller
(15) Input Shaft
(16) Variable Swashplate
(17) Piston (Pump)
(18) Cylinder Block (Pump)
(19) Cylinder Block (Motor)
(20) Piston (Motor)
(21) Fixed Swashplate
(22) Bypath Valve
a: To Bi-speed Valve
b: To 3-Point Linkage
X: High Pressure Oil
Y: Low Pressure Oil
Z: Suction or Drain Oil
9Y1211109TRM0005US0
KiSC issued 11, 2014 A