Kubota RTV 900 Workshop Manual page 20

RTV900, WSM
After dynamic brake, operating brake and pulling VHT pressure release knob creates a bypass circuit
When driving, releasing the pedal to halt the vehicle places the system under the status of dynamic braking, as
described in the previous section.
Immediately after halting the vehicle by pressing the brake pedal, or when the deviation from neutral position of
variable swashplate (17) is significant, a torque will exist between HST and the transmission.
Under the conditions, shifting the gears is extremely difficult because of friction in the gear box.
Operating the brake and pulling the VHT pressure release knob creates a bypass circuit, which eliminates the
difference in pressures between high pressure side and low pressure side.
This operation releases the torque remaining in the transmission.
As a result, smooth shifting of gears is made possible.
For oil flow, a loop circuit is made through a bypass valve, between C port and D port of the fixed motor. This
system makes free rotation of the output shaft (14) possible.
The bypass spool c must operate in synchronization with braking, and the bypass spool b must be controlled
manually by the VHT pressure release knob.
9-M11
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
W1015199
KiSC issued 04, 2006 A