WHAT IS IT ?
Lapping, in an
automotive differential, is a process where two gear surfaces are
run together in a Gleason Lapping machine, using a medium of
carborundum abrasive powder and oil which forms a paste solution,
which in turn works on the contact surface areas. The two surfaces
are the gear contact areas of the Crownwheel and Pinion.
The lapping process is achieved by setting up the crownwheel and
pinion in the lapping machine in the same way that it would run in
The operator then
observes the wear pattern and sets the machine to compensate and
then completes the process using various techniques to reduce the
high points of contact to the same level as the low points of
contact, whilst maintaining the correct curvature of the tooth
profile, and thus eliminating the cause of concentrated contact
area. At the completion of the process, all sharp edges are ground
(chamfered) to further improve the quality of contact between the
WHY LAP A CWP ?
The need to lap a crownwheel and pinion can be caused by many
influencing factors, including, but not limited to:
components. Vehicle loading.
faults. Result of roads conditions (flood, dust).
Worn bearings. Old
The quality of the
results of re-lapping will be directly relative to the condition of
the gearset prior to the lapping process, but in most cases should
enable the gearset to provide long term, reliable service in a
CAN ALL GEARSETS
BE LAPPED ?
machine is capable of lapping hypoid and spiral bevel gears, but we
need to maintain a comprehensive range of mountings. This also
includes any gears that change the drive path by 90 degrees, or at
right angles. It is important to note that lapping a gearset can
only proceed if the specially trained operator can assess that the
end result will be a serviceable gearset. Crownwheel and pinions
that are badly worn or scuffed, (due to lack of oil or foreign
matter), can be re-lapped, but the result may be less desirable. It
is possible that gearsets with broken teeth can have the teeth
welded back on and then the gearset re-lapped, but only in desperate
CROWNWHEEL AND PINIONS , SKILLFULLY RE-LAPPED WILL PROVIDE AN
INEXPENSIVE REPAIR AND/OR
THE NEED TO AVOID REPLACEMENT OF A GEARSET THAT MAY BE TEMPORARILY
OR NO LONGER AVAILABLE.