Service Manual

1. Remove pipe plug and connect gauge directly
to filter base. Although thread
is 1/4-18 NPT, it
will accept a 1/2-20 SAE fitting for test purposes.
2. Operate engine. Normal charge pressure is 30-
90
PSI. Refer to appropriate Troubleshooting
Chart for troubleshooting procedures.
Always check implement lift pressure relief
valves for signs
of tampering if charge pres-
suer
is low. A relief valve set too high will
cause permanent internal damage to charge
pump and hydrostatic transmission.
If damage
has occurred, replace transmission do not
operate
lift system until hydraulic lift control
valve has been replaced, or relief valve ad-
justed.
Do not adjust relief valve without fac-
tory assistance.
REPAIR OPERATIONS
GENERAL INFORMATION
Hydrostatic transmission, transaxle, and hydraulic
lift system may all be serviced without removing
complete transmission system from tractor. Detailed
repair operations are given for in-vehicle service.
A
procedure for removing transmission/transaxle from
tractor as an assembly
is also given at end of this
section.
An Crow Foot wrench
is necessary to perform
in-vehicle transmission and transaxle service. Two
sources of
this wrench are: Distributors of Williams
products (Williams #BC-1003) and Sears Roebuck
&
Co. (Sears #9HT4362).
HYDRAULIC HOSES
HYDRAULIC
LIFT CONTROL VALVE
REMOVAL
1. If applicable, remove battery (Fig. 19C).
2. Remove seat and rear fender.
3. Remove control cover plate and rear hood-
stand cover plate.
4. Remove
LH side cover.
5. Support rear of tractor with jack stands placed
under rear footrest cross rod.
6. Remove LH wheel. If replacing charge pump
hose, also remove
RH wheel.
7. Disconnect three hoses (Fig. 19A). Remove two
control valve bracket bolts shown in Fig. 19A
or 19C. Free long hose from clamp and tie se-
curing it to tractor.
FIG. 19s. Early Model Control Valve
FIG. 19A Disconnect Hoses
15-
8. Pull control valve out enough to permit clamp-
ing it to rear edge of battery tray (Fig. 19B).
Do not secure valve by its handle when
loos-
ening hose or it may break.
9. Disconnect charge pump output hose, connect-
ed to “IN” port on control valve.
10. Remove control valve from tractor for repair
or replacement of valve/hoses.
11. If replacing charge pump output hose, free it
from clamp inside hoodstand. Disconnect hose
from charge pump outlet, and pull hose out of
hoodstand toward rear.
912
FIG. 19C. Late Model Control Valve
INSTALLATION
1. Follow removal instructions in reverse.
a.
Use care to prevent dirt from entering system,
particularly when working charge pump out-
let hose through hoodstand
b. Clamp valve as shown in Fig. 198 or 19C
when tightening charge pump outlet hose.
c. Operate hydraulic system before installing
covers.
Check performance and for oil leaks.
Exercise lift system
for one minute to expel
any trapped air.
d. If control valve was rebuilt or replaced, per-
form an implement lift system pressure
check.
e. Check that hoses are routed properly and
secured with clamps and ties as required,