Drum brake

See also: Brake (homonymy)

A brake drum is a system of old Frein consisted of a Cloche (the Tambour), inside which at least two jaws are provided with trimmings. Their function is to deviate thanks to cams or pistons which cause the friction of the trimming in the drum.

These cams are actuated by a power-control (cable, tie) and the pistons are actuated by a hydraulic control.

Compared to the Brake disc characterized by its progressiveness, the drum brake tends to slow down in all or anything , because when the jaws are drawn aside, they are “aspired” by the drum. When the drum brake is powerful, it easily causes blockings of wheels dangerous for the stability of the vehicle.

When the jaws are drawn aside by only one cam, the brake is not very effective but the risk of blocking is weak.

When they are isolated in several points (brake doubles cam, or more), the number of points of aspiration of the trimmings increases, and with him, the force of braking and the risk of blocking.

This is why the majority of the vehicles, especially the two-wheeled vehicles, are now equipped with disc brakes.

On the technical plan, the drum brake is relatively tight, generally cooling by its circumference sometimes provided with wings. Despite everything, cooling is relatively ineffective, which can involve an overheating. However certain models have hearing of cooling which force the air to circulate inside.

The deformations of the drums and their low endurance with the heating involve the progressive disappearance of this type of brake on the recent vehicles. Moreover, the disc brakes generate less gyroscopic effect particularly prejudicial with Motocyclette.

See too

the Wikilivre of tribology and in particular the paragraph devoted to current research on braking.

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