Dealer Service 21
29977 (Rev. 1/23/2009)
DEALER SERVICE
The information in this section is written for dealer ser-
vice personnel. The repair described herein requires
special skills and tools. If your shop is not properly
equipped or your mechanics are not properly trained in
this type of repair, you may be time and money ahead
to replace complete assemblies.
■ Lower cutter to ground, turn tractor engine off
and remove key before performing any mainte-
nance or service.
■ When completing a maintenance or service
function, make sure all safety shields are in good
condition and properly installed before placing cut-
ter in service.
■ Always use personal protection devices such
as eye and ear protection when performing mainte-
nance and service functions.
GEARBOX MAINTENANCE
Read this complete section before any repair. Many
steps are dependent on each other.
Always maintain gearboxes half full of 90W gear lube.
Be sure proper vent plugs are installed in wing gear-
boxes.
Troubleshooting is an important part of gearbox main-
tenance. Check for leakage and bad bearings.
Leakage may be caused by a vent plug not venting.
The vent plug has an internal relief valve set at approx-
imately 5 psi. Remove plug, apply low air pressure to
bottom of plug, and be sure it is venting out the top.
Operating gearboxes over half full of gear lube may
also cause seals to leak. Also check for cracks in hous-
ing. If either of these conditions exists, correct them,
clean up area where leakage was evident, put cutter
back into service and check area for leakage.
Bearing misadjustment or failure is indicated by noise
and excessive side and end play in gear shafts. If
noted, readjust bearings or disassemble and inspect
bearings. Excessive end play in vertical shafts may
also indicate crossbars are not properly shimmed.
Leakage may occur at these points: top cover, vertical
or horizontal seals and at the square ring between side
housings and gearbox.
Leakage is a very serious problem and must be cor-
rected immediately.
Leakage at the horizontal seal, top cover, or between
the housing and side covers and side gear housings
can be corrected without removing gearbox from cutter.
The sealant recommended for gearbox repair is Per-
matex Aviation 3D Form-A Gasket
®
or equivalent.
Leakage Repair
Repair top cover leakage by removing and cleaning top
cover and top of gearbox.
Use care to prevent foreign material from entering the
gearbox. Apply a thin coat of Permatex to top of gear-
box and cover bolts. Install a new gasket and replace
cover.
Repair horizontal seal or leakage between side hous-
ing and gearbox, remove top cover and siphon gear
lube from box. Remove the leaking seal and replace
(refer to Seal Installation). Use care to prevent rolling
seal lip under. Repair leakage between side housing
and gearbox by removing housing and replacing
square O-ring. Be sure to reinstall shims when install-
ing side housing.
Seal Installation
Proper seal installation is important. An improperly
installed seal will leak and could result in gearbox fail-
ure.
Clean area in housing or cap where seal outer diame-
ter seats and apply a thin coat of gasket sealant.
Inspect gear shafts and sleeves. Pay specific attention
to areas where seals seat. Check for cracks, grooves,
nicks or bumps. Replace housing, shaft or sleeve if
damage cannot be repaired by resurfacing with emery
cloth.
Lubricate seal lip and carefully guide over sleeve or
shaft using a blunt tool such as a letter opener. Be
careful not to roll seal lip under. Do not use a knife
blade as it will nick and ruin seal.
Place seal squarely on housing (spring-loaded lip
toward inside of gearbox). Select a seal driver, a piece
of pipe or tubing with an OD that will set on outside
edge of seal but will clear housing. A driver that is too
small will bow seal cage and ruin seal.
Carefully press seal into housing, preventing distortion
to metal seal cage. Seat vertical seal firmly and
squarely against machined surface and horizontal seal
flush with housing.
Distortion to seal cage or damage to seal lip will cause
seal to leak. Remove and replace seals damaged in
installation.
