There are 2 versions of brake camshaft, old
version & new version. The difference is that new version has
a slot on the S head parallel to the involute. This is designed
to reduce the heat caused by friction and
increase the life of brake drum, also for safety
factor. The contact area between involute surface and roller of
old camshaft is big, when releasing brake, the large friction
resistance produces large heat between brake lining and brake
drum, it will cause tyre blow-out. The slot on the new version
camshaft has solved this problem, and improves the
safety.
