Kubota RTV1140CPX, Workshop Manual

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TRANSMISSION
RTV1140CPX, WSM
2-M5
(2) Oil Flow
A charge pump (18) is used to feed oil to the hydrostatic transmission (HST). The oil coming from the charge
pump (18) flows through the oil filter cartridge (5) into the HST main circuit and regulator valve (4). At this time, the
servo regulator valve and HST main circuit (that is closed with the control lever at neutral position) are kept at the
charge relief valve (12) set pressure. Step on the pedal, and the regulator valve (4) switches its oil passage to allow
the oil into the service port. Being interlocked with the servo piston (14), the swashplate now tilts to activate the
variable pump (15). Pressurized oil is then forced into the stationary motor (11), which then rotates to circulate oil
between the pump and motor.
The heavier the load on the output shaft (9), the higher the pressure of the oil coming from the pump (15). Now
the assist motor (10) is activated to increase the output torque. When the load on the output shaft (9) decreases, the
oil pressure in the main circuit also drops and the assist motor (10) returns to its neutral position and just the stationary
motor (11) maintains torque to the output shaft (9). Now a closed circuit is formed by the pump (15) and stationary
motor (11).
The unload valve (14) is composed of the manual operation spool and the spool that operates in synchronization
with the brake.
(Reference)
• Valve Setting Pressure [Oil temperature: 45 to 55 °C (113 to 131 °F)]
– Engine Speed: 1350 min
− 1
(rpm)
Charge Relief Valve: 0.52 to 0.71 MPa (5.3 to 7.3 kgf/cm
2
, 75 to 100 psi)
– Engine Speed: 3000 min
− 1
(rpm)
Check and High Pressure Relief Valve
(Forward) 22.6 to 26.5 MPa (231 to 270 kgf/cm
2
, 3280 to 3840 psi)
(Reverse) 18.9 to 21.5 MPa (193 to 219 kgf/cm
2
, 2750 to 3110 psi)
9Y1210293TRM0005US0
(1) HST Assembly
(2) Control Lever (Pedal)
(3) Servo Regulator Assembly
(4) Regulator Valve
(5) Oil Filter Cartridge
(6) Anti-cavitation Valve (7) Check and High Pressure
Relief Valve
(8) Control Piston
(9) Output Shaft (Motor Shaft)
(10) Cylinder Block (Assist Motor)
(11) Cylinder Block
(Stationary Motor)
(12) Charge Relief Valve
(13) Unload Valve
(14) Servo Piston
(15) Cylinder Block (HST Pump)
(16) Tank
(17) Oil Filter Cartridge
(18) Charge Pump
(19) Input Shaft (Pump Shaft)
KiSC issued 05, 2014 A