John Deere stx38 - Manual (Page 200)

5 - 36
3/21/97
TESTS AND ADJUSTMENTS POWER TRAIN
CLUTCH SPRING ADJUSTMENT
IMPORTANT: Anytime the brake or clutch spring
need to be adjusted, both must be examined to
ensure desired results will be obtained.
1. Unlock park brake (B) and release pedal (A).
2. Measure clutch spring length (F).
IMPORTANT: STX30 & STX38 (SN —210000)
clutch spring length is 47mm (1.85 in.). STX38 &
STX46 (late models) clutch spring length is 42—
45 mm (1.65—1.77 in.).
3. Adjust rear idler (G) until clutch spring length meets
above specification.
4. Depress pedal and lock park brake.
5. Remove belt guide (H) to access idler nut (I).
6. Adjust idler rearward slightly if measurement is less
than specification. Adjust idler forward slightly if
measurement is greater than specification. Tighten
idler nut (I).
7. Recycle pedal in and out of park two or three times,
remeasuring clutch spring length each time.
Measurement must fall within specification each
time. If not, continue to adjust rear idler slightly
until it does.
8. Install belt guide (H). This clutch spring setting
should provide proper belt tension to pull tractor up
a 17° slope in all three lower gears.
9. Install battery, if removed.
Repeat Test Drive—
1. Attach mower deck to tractor—this will help
stabilize the tractor.
2. If brake components were not replaced, drive
tractor in a safe, open, and level area at fast idle in
high gear. Apply a “panic stop” force (no more than
50 pounds of force) to brake pedal—tractor must
stop at rate of 30.5 cm (12 in.) per mph.
3. Carefully test drive tractor to see if traction drive
system pulls tractor up a 17° slope in all three
lower gears.
4. Look for a steady pull in all three lower gears up the
slope. If tractor fails traction test, inspect traction
drive belt:
• if belt is excessively worn, stretched, glazed, or
unraveling—replace it
• if belt is not excessively worn, make finite
adjustments above or below specification to gain
proper response in traction drive system.
Remember—to lengthen clutch spring causes
increased traction and aggressiveness; to
shorten
clutch spring causes decreased traction
and aggressiveness.
5. Drive tractor onto a 17° slope and lock clutch/brake
pedal in PARK position. Check that park brake
holds tractor stationary on slope and that tractor
does not creep downward once park brake is set.
6. If tractor fails either brake test, inspect brake
assembly components, replace as necessary, and
repeat all adjustment procedures and drive tests.
c
CAUTION
DO NOT engage clutch/brake pedal too
aggressively or tractor may tip over backwards.
It is recommended that you install the mower
deck before performing the test drive on a 17°
slope.
M42579
B
F
A
G
H
I
M42597
M42598