Service Manual

2 - 10 5xi Series Tractor Hydraulic Service Manual
THEORY OF OPERATION
2
Due to internal leakage, fluid being returned to
the inlet side of the pump from the exhaust side
of the motor is less than required by the pump.
To replace this needed fluid, check valves are
located in each side of closed loop. The check
valve located on the low pressure side of the
pump will open allowing fluid to enter loop, from
the charge pump circuit, to make up leakage
losses.
(A) Pump
(B) Motor
(C) Low Pressure
(D) High Pressure
(E) Charge Pump
(F) Check Valves
Internal acceleration valves are used in both
forward and reverse directions. These valves
are spring loaded to close “slowly” as pressure
(load) increases. These valves control the rate
of acceleration of the motor output shaft, assist in
providing a positive neutral, and permit hand
pushing the tractor without operating the engine.
(A) From Sump
(B) Charge Pump
(C) Input Shaft
(D) To Lift
(E) Hydraulic Pump
(F) Acceleration
Valves
(G) To Sump
(H) Hydraulic Motor
(I) Output Shaft
(J) Forward/Reverse
Check Valves
(K) From Lift
(L) Charge Pressure
Relief Valve
(M) Motion Control Shaft
In operation, as the tractor’s motion control lever
is moved out of neutral, the appropriate
acceleration valve bleeds off some of the high
pressure oil before it closes. This initial
temporary pressure reduction results in
smoother tractor acceleration from a standstill.
(A) Dampening Piston
(B) Pump
(C) Control Shaft
(D) Aux. Hyd. Valve
(E) Filter
(F) Charge Pump
(G) Check Valve
(H) Acceleration
Valves
(I) Charge Relief
Valve
(J) Motor
(K) High Pressure
(L) Low Pressure (30-90
PSI)
(M) Transaxle Sump
(N) Lift System Pressure
(700 PSI (48 bar) with
manual steering; 725
PSI (50 bar) with
power steering
0202-005
0202-006
0202-007