John Deere stx38 - Manual (Page 252)

6 - 20
3/21/97
DIAGNOSIS HYDROSTATIC POWER TRAIN
DIAGNOSIS CONTINUED
Test Conditions:
• Tractor operating in test area. • Tests run at engine slow idle and fast idle.
• Engine at operating temperature. • Hydro run through full range of speeds in both
directions.
Test/Check Point Normal If Not Normal
1. Engine performance. Engine running smoothly throughout
throttle range. Adjust, tune, or repair engine.
2. Belt traction drive system. Belt not slipping, squealing, or vibrating
excessively. Check belt condition, check
adjustment and condition of
idlers and guides. Adjust, repair
or replace components as
needed.
3. Shift linkage operation. Shifting is smooth, full speed obtained, and
constant speed is maintained (little or no
movement in linkage when shift lever is
released). Check shift linkage condition.
Check bellcrank friction discs
and tensioning spring
adjustment. Adjust, repair or
replace components as needed.
4. Return-to-neutral/brake
and park brake linkage
operation.
Brakes stop tractor and park brake holds
tractor stationary on 17° slope. Return-to-
neutral/brake linkage engages brake and
returns shift lever linkage back into neutral. Check brake pedal, return-to-
neutral, and park brake linkages.
Check brake disc and friction
pucks for wear. Adjust, repair or
replace components as needed.
5. Transaxle performance. Transport (free-wheel) valve when
engaged allows operator to push tractor
with little effort. When disengaged, tractor
moves only by starting engine and
engaging transaxle. Transaxle operates
smoothly throughout forward and reverse
ranges.
STX38
(M00STXC210001—270000)
(M00STXJ270001—290000)
STX46
(M00STXG240001—270000)
(M00STXL270001—290000)
One or more piston springs may be missing
in the pump or motor cylinder block. With
the spring missing, piston washer may slip
out of piston and damage surfaces of the
cylinder blocks, plates, and center block.
Check transport (free-wheel)
valve and linkage adjustment
and condition. Check hydro
internal components and fluid
level. See drive belt adjustment
and bellcrank spring tension
adjustment.
Adjust, repair or replace
components as needed.
6. Axles, wheels, and tires. Axles, wheels, and tires in good shape and
functioning properly. Check axles and wheel for
straitness, check condition of
keys and keyways, washers, and
snap rings. Check tires for tread
wear and proper inflation. Repair
or replace components as
needed.