wsm RTV-X1120D Workshop Manual page 226

RTV-X900, RTV-X1120D, WSM
Control Lever Activated (with Control Lever at Desired Position)
When the control lever has been set to a desired position, the regulator's feedback lever (7) and the servo piston
(8) get balanced with each other. Now the regulator spool (3) goes to the neutral position. The pump's variable
swashplate interlocked with the servo piston is kept in place to achieve a desired speed.
The load on the HST pump is not constant, however. A heavier load returns the servo piston toward the
slow-down side. In so doing, the feedback lever works on the spool to switch the hydraulic circuit to the speed-up side.
Then the servo piston is brought back (speed-up) until it gets well balanced with the feedback lever.
A smaller load, on the other hand, moves the servo piston toward the speed-up side. The feedback lever now
works on the regulator spool to switch the hydraulic circuit to the slow-down side. The servo piston's charge pressure
is let out at the slow-down side and introduced at the speed-up side. Then the servo piston is brought back
(slow-down) until it gets well balanced with the feedback lever. This cycle of motions is repeated to keep the desired
position.
2-M11
TRANSMISSION
(1) Servo Adjusting Screw
(2) Regulator Valve Assembly
(3) Regulator Spool
(4) Pin B (Fixed with Spool)
(5) Pin A
(Fixed with Regulator Shaft)
(6) Control Lever
(7) Feedback Lever
(8) Servo Piston
(9) Piston Adjusting Screw
(10) HST Housing
a: Drain to HST Housing
b: From Charge Pump
(Charge Pressure)
A: Speed Up
B: Slow Down
9Y1210946TRM0012US0
KiSC issued 01, 2014 A