Cub Cadet 28HP Tank 53AB5JEZ630, Operator'S And Service Manual, Page: 27 / 36

27
Performance Adjustments
A. High Speed Tracking Adjustment
If mower tracks to one side with both lap bars in fully
forward position:
1. Check air pressure in all four tires:
a. Pressure should be within specified ranges
and balanced side-to-side.
b. Rear tires 10-12 psi. recommended (20 psi
MAX.)
c. Front tires 20-25 psi. recommended (28 psi
MAX.
2. Check hydraulic fluid level (Ref. Engine
owner’s manual)
3. Verify that the mower does not creep when
the engine is running, the lap bars are in the
neutral position and the parking brake is
released. (Refer to section D-3 on page 21 of
this manual if this condition exists).
4. Recheck the tracking after any adjustments
based on the above.
5. If uneven tracking persists, adjust as follows.
(see Fig. 10)
a. Unit tracks to the RIGHT, adjust Left lap
bar stop bolt to make it longer.
b. Unit tracks to the LEFT, adjust Right lap
bar stop bolt to make it longer.
6. Re-check the tracking and make any fine tun-
ing adjustments to the lap bar stop bolts as
required.
Note:
If stop bolt is adjusted too far, track-
ing problem will change sides. Make the fine
tuning adjustments by shortening the same
bolt.
Figure. 10
Lap Bar Stop Bolt
B. Enginge RPM Check and Adjustment
Description High RPM Spec. Low RPM Spec.
28.2 Hp Caterpillar 3675 +/-50 1200 +/-100
NOTE: RPM Specs. are for free running engines under no load.
1. Verify that the lap bars are in the neutral posi-
tion, the parking brake is on, and the PTO
drive is disengaged.
2. Start the mower and let it run at approximately
half throttle for 3-5 minutes to bring the engine
up to operating temperature.
3. Locate the Hour Meter/Tachometer/ Service
Minder display on the right hand operator con-
trol panel. (see Fig.1 on page 9 of the manual)
This display defaults to Tachometer mode
when engine is running.
4. Move the throttle lever to the high speed posi-
tion and note the RPM reading on the display.
5. Move the throttle lever back to the low speed
position and again note the displayed RPM’s.
6. Compare these noted RPM readings to the
specifications in Table 1, for the engine that is
on your mower.
7. If the readings do not correspond to the
ranges in the table, refer to the engine
owner’s manual for the proper adjustment pro-
cedures.
8. If adjustments per the engine operator’s man-
ual do not result in proper RPM readings, con-
tact your service technician.
9. Note: The throttle cable sheath may shrink or
slip over time, changing the relationship
between the throttle lever on the left hand
operator control panel and the throttle arm on
the engine. To readjust the throttle cable:
a. Make sure the engine is off, place lap bars
in the neutral position, set the parking
brake, and disconnect and ground both of
the spark plug wires.
b. Locate and loosen the cable clamp on the
engine throttle plate.
c. Place the operator’s throttle lever to the
high speed position and then slide the
cable through the clamp until the throttle
arm is in the full throttle position. (Ref.
Engine owner’s manual)
d. Tighten the cable clamp.
e. Move the operator’s throttle lever between
high and low speed and verify that the
engine throttle arm also moves through it’s
full range of motion.
f. Repeat as required to obtain proper throt-
tle adjustment.
g. Verify proper throttle adjustment by check-
ing RPM readings as outlined above.