ZYBC Brake Electro Hydraulic Thruster Drum Brakes From China Manufacturer

Introduction of Electro Hydraulic Thruster Drum Brakes:

Electro hydraulic thruster (commonly called thruster) drum brake is a device used to retard the speed of moving machinery and to stop it accurately to the desired position. When the braking force is applied to the brake shoes by a pre-stressed compression spring, the shoes press on the rotating brake drum retarding its speed and finally stopping it. The releasing of the brake drum and compressing of the spring is done by the thruster.

Thruster operated drum brakes are mainly used in material lifting and handling equipment (in the field of applications like ports, steel and metallurgy, mining, etc.) mainly because their “soft / smooth” braking and 'fail-to-safety' designs to ensure safety to men and machines. These brakes are called 'fail-to-safety' because the braking is obtained by electrical current loss under the action of pre-stressed compression spring. In case of current loss (power failure), these brakes stop the motor or the driven load.

Construction of Thruster Operated Drum Brakes

As shown in above figure, a thruster operated drum brake has a pair of brake shoes with lining (friction pads). The lining is either glued or riveted to the brake shoe. The shoes are hinged on main (internal) arm and side (external) arm of the brake. Each arm is fitted to the mounting base (called base) with a hinge pin. These arms are connected to each other on top by a tie rod, which is hinged in the main arm and locked to the swivel block in the side arm, by nuts. A crank lever is hinged on the main arm and the other end is fixed to the top clevis of the thruster by a hinge pin. A brake spring is fixed on the crank lever. It is pretensioned by a screw and a locknut on the lever. The pre-tension in the spring decides the braking torque. The thruster is fitted on the base by a hinge pin. When the thruster is not energized, the brake shoes are pressed on the brake drum fitted on the drive motor shaft and hold it under the effect of braking force provided by the brake spring. In this condition, the brake is applied and the drum cannot rotate. When the thruster is energized, its piston travels upwards and the crank lever turns which pushes the tie rod and compresses the brake spring. Simultaneously it moves main arm and side arm, releasing the brake drum.

Working of Thruster Operated Drum Brakes 

Thruster operated drum brakes are spring applied and electrically released. Following figure shows how the braking force is generated by the brake spring for braking (applying brake).

A thruster operated drum brake uses the force exerted by the brake spring for braking. As shown in above figure, the compressed brake spring tends to expand itself creating the extension force (Fx). A force (Fa) is created by the extension force (Fx) and is conveyed to the brake arms which is equal but in the opposite direction in each arm. Due to the relationship of the distances (A and B) that are there is in the arms with respect to the rotation axis (O), a clamping force (Fp) is created which is equal in both brake shoes but in the opposite direction that makes the brake to operate (apply/close). The clamping force created in the brake shoe (Fp) generates a friction force (Fr) at a tangent to the drum in one direction or the other depending on the rotation direction of the drum. The result of adding the two friction forces of brake shoes is called/known as braking force

Please contact us if you are intereted in our electro hydraulic thruster drum brake, we will send you our product catalogue.

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