The synchronization system was created with the intention to
make easy the gear engaging in automotive transmissions. The speed
difference of the shafts is reduced during the gearshift operation
by means of sliding friction of the synchronizer rings. The
constant friction performance can be improved and the wear can be
simultaneously reduced either by additives in the oil of the
transmission or by careful selection of the friction material for
the synchronizer rings.
Nowadays, brass or steel meet the requirement of both friction
surface and resistance on the driving lugs. The friction
coefficient of the surface can be increased by scatter sintered
coatings, molybdenum or carbon linings that are joined to the
carrier material using complex manufacturing processes.
A new concept transforms this continuous friction lining into
many single friction elements that are guided by
"pockets" in the synchronizer ring. These "friction
lining pads" require less material than the conventional
solution (steel and friction compound) which leads to a reduction
in the overall weight, especially in cases where non-metallic
friction material is used. This increases the efficiency by equal
performance and reduced drag torque, and also reduces the losses in
the gearbox which is a benefit for fuel-saving drive trains. In
addition, the material of the carrier supports higher mechanical
stresses, because steel is used instead of brass. Also materials
characterized by excellent friction properties when used as
friction linings can be chosen.
In theory almost every material can be used as friction pads,
such as the already proven scatter sintered coatings or any
combination of materials. Optimum friction elements for such
systems include pads made with nonmetallic materials, as various
resins containing friction modifiers or pads from known brass
alloys.