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In this type of braking mechanism, friction forces are produced among the components attached to a fixed part of the vehicle and the internal or external surface of the brake drum.
Drum brakes are divided into internal drum brakes with shoes, and external drum brakes with friction belts. The internal brakes are rated according to their brake shoes arrangement.
Simplex type: brakes equipped with a primary and a secondary brake shoe without any interaction between them. The S and Z Cam brakes, largely used in Brazilian vehicles and supplied by Master, are of the Simplex type. .
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1 - Drum rotation |
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2 - Inlet Force (Self energization) |
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3 - Inlet force (Self reduction) |
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4 - Torque |
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5 - “S” Cam |
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6 - Primary brake shoe |
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7 - Secondary brake shoe |
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8 - Anchor pins |
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"S Cam" Brake
| Tube S Cam |
Tubeless S Cam |
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The S-Cam Master brakes have been developed for commercial vehicles running on different types of roads. They are mechanically driven by a S-shaped camshaft. The movement of the cam determines the opening of the shoes in one of the ends. The other end remains secured and sustained by retaining springs. The return spring close to the camshaft is responsible for the contact between both pars and also for the return of the shoe to its initial conditions after the brake is applied.
"Z Came" Brake
The Z cam produced by Master has evolved from the S-cam drum brakes. Equal forces are produced in the primary and secondary brake shoes when the camshaft is driven. This feature provides the set with a uniform torque and even wear on the brake linings. The adjusting mechanism is integrated to the brake, so its adjusting function does not requires additional components. This mechanism`s working principle keeps the linings always close to the drum, in addition to warning about adjustment needs. The adjustment can be performed manually or automatically. As the sliding shoes feature reduced sensitivity to speed, their efficiency is not decreased. The high performance of this brake type provides safer braking than regular drum brakes.
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