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Telma Retarder


Telma induction brakes, commonly referred to as electric or electromagnetic retarders, provide a braking resistor: It relieves conventional braking systems by dissipating a significant part of the braking energy.

Telma induction brakes dissipate braking energy by generating Foucault currents. Telma induction brakes consist of a fixed stator and a pair of rotors working together with a drive shaft that makes the stator rotate. The stator and rotors are mounted coaxially opposite each other; The air gap between them separates the rotors from the stator, preventing friction.


The stator acts as an inductor; It consists of a pair of electromagnets that create the magnetic fields necessary to generate Foucault currents in the rotors when an uninterrupted electric current passes through them.

The rotors perform the induced function. As Foucault currents pass through the rotors made of a specially designed conductive material, they pass through the magnetic fields produced by the stator, while the drive shaft causes them to rotate.


By definition, Foucault currents occur in a conductive metal mass, while this metal mass is placed in a varying magnetic field. In the case of Telma brand induction brakes, the variability of the magnetic field to which the rotors are subject is achieved by their rotation. Foucault currents revolve around magnetic currents, also called eddy currents.

The formation of Foucault currents in the rotor causes Laplace forces to occur, which prevents the rotor from rotating. The braking torque produced in this way and acting on the drive shaft causes the vehicle to slow down.

Foucault currents cause the rotor temperature to rise gradually, which the rotors evacuate by ventilation.

Thanks to Telma induction brakes, it is possible to effectively slow down the rotating shaft without friction and wear.

Induction brakes look simple in principle, but are subject to complex laws of physics such as matter resistance, electromagnetics, thermodynamics or fluid mechanics. Telma's acknowledged expertise in electromagnetic induction braking is based on a detailed modeling of all the laws of physics that affect the operation of induction brakes.


This modeling is enhanced by years of practical experience and distinctive laboratory inspections.

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