Lesson l/Learning Event 1
A friction lining riveted or bonded to the face of the shoe makes
contact with the inner surface of the brake drum when the brake is
applied. On the rivetedtype lining, brass rivets are usually used
because brass does not unduly score the drum when the lining is worn.
Aluminum rivets are not very satisfactory because they are corroded
very readily by salt water. The bonded lining is not riveted but is
bonded directly to the shoe with a special cement.
Differences in brake design and conditions of operation make it
necessary to have various types of brake linings.
The molded brake lining is made of dense, hard, compact
materials and is cut into blocks to fit different sizes of
brake shoes. Its frictional qualities are low because it has
a smooth surface, but it dissipates heat rapidly and wears
longer than the woven type.
The woven brake lining is made of asbestos fiber, cotton
fiber, and copper or bronze wire. After being woven, the
lining is treated with compounds intended to lessen the
effects of oil and water if they should come in contact with
the lining. However, oil, in particular, will reduce the
frictional quality of the lining even after treatment. The
lining is also compressed and heat treated before being
installed. The main advantage of a woven lining is its
frictional qualities. However, it does not dissipate heat as
rapidly or wear as well as molded brake linings. This type of
lining is generally not used in automotive vehicles.
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