Kubota RTV 900 Workshop Manual page 18

RTV900, WSM
Pedal pressed fully, under heavy load and input horsepower control
Let's suppose that the pedal is fully pressed. The control lever is activated by the pedal to switch the regulator
valve's hydraulic circuit. The servo piston (4) is then actuated to tilt the pump's variable swashplate to maximum (see
the above illustration).
The pump cylinder block (5) is driven by the input shaft (19) to put the oil under high pressure and to feed it at the
highest rate out of the pump port A. The pressure-fed oil flows into the motor's port D along the circuit. The oil from
the HST pump then reaches the pressure level 17.7 MPa (180 kgf/cm
swashplate (8) all the way. At this time, the assist motor reaches its maximum capacity.
If the load becomes heavier, the variable swashplate (pump) moves toward to the neutral position under the
reaction of HST pump itself. With the variable swashplate tilted back to neutral side, the engine load becomes lighter
and the engine rpm higher again. At this time, the pump's delivery rate drops, but the recovered engine rpm enables
the delivery oil pressure to go up to the high-pressure relief valve setting. Now the maximum torque is obtained.
2
, 2560 psi) to tilt the assist motor's variable
9-M9
NEW TRANSMISSION
(1) Pedal
(2) Regulator Valve Assembly
(3) Regulator Spool
(4) Servo Piston
(5) Cylinder Block
(6) HST Housing
(7) Control Piston
(8) Variable Swashplate
(Assist Motor)
(9) Cylinder Block (Assist Motor)
(10) Cylinder Block
(Stationary Motor)
(11) Check and High Pressure
Relief Valve
(12) Bypass Valve
(13) Transmission Case
(14) Output Shaft
(15) Charge Relief Valve
(16) Oil Filter Cartridge (Suction)
(17) Variable Swashplate
(HST Pump)
(18) Charge Pump
(19) Input Shaft
(20) Oil Cooler
(21) Oil Filter Cartridge
a : To HST Housing
b : Connects with Cable for
VHT Pressure Release
Knob
c : Connects with Brake Cam
Lever
W1014628
KiSC issued 04, 2006 A