Telma retarder
Encyclopedia
A Telma retarder is friction
less electromagnetic
braking system
made by Telma, a company that is part of the Valeo
group, a French
automotive components manufacturer. A Telma retarder is an eddy current brake system.
The system works by energising coils with alternating polarities in order to create an electromagnetic field. Eddy current
s are generated in two rotors
as they pass through this field, applying a braking torque to their rotation and therefore to the driveshaft
s attached to them. The stator
houses the electromagnetic coils and is attached to the chassis
, the transmission
or an axle
of the vehicle. Round discs called rotors are attached to the driveline
. A thin air gap is maintained between the rotors and the coils. In normal operation, the rotor turns freely but when electric current flows through the coils, eddy currents are created that apply braking torque to the rotors and therefore to the driveline.
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
less electromagnetic
Electromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...
braking system
Brake
A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The rest of this article is dedicated to various types of vehicular brakes....
made by Telma, a company that is part of the Valeo
Valeo
Valeo is a French automotive components manufacturer.-History:The Société Anonyme Française du Ferodo was founded in 1923 in Saint-Ouen, a suburb of Paris...
group, a French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
automotive components manufacturer. A Telma retarder is an eddy current brake system.
The system works by energising coils with alternating polarities in order to create an electromagnetic field. Eddy current
Eddy current
Eddy currents are electric currents induced in conductors when a conductor is exposed to a changing magnetic field; due to relative motion of the field source and conductor or due to variations of the field with time. This can cause a circulating flow of electrons, or current, within the body of...
s are generated in two rotors
Disc brake
The disc brake or disk brake is a device for slowing or stopping the rotation of a wheel while it is in motion.A brake disc is usually made of cast iron, but may in some cases be made of composites such as reinforced carbon–carbon or ceramic matrix composites. This is connected to the wheel and/or...
as they pass through this field, applying a braking torque to their rotation and therefore to the driveshaft
Driveshaft
A drive shaft, driveshaft, driving shaft, propeller shaft, or Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement...
s attached to them. The stator
Stator
The stator is the stationary part of a rotor system, found in an electric generator, electric motor and biological rotors.Depending on the configuration of a spinning electromotive device the stator may act as the field magnet, interacting with the armature to create motion, or it may act as the...
houses the electromagnetic coils and is attached to the chassis
Chassis
A chassis consists of an internal framework that supports a man-made object. It is analogous to an animal's skeleton. An example of a chassis is the underpart of a motor vehicle, consisting of the frame with the wheels and machinery.- Vehicles :In the case of vehicles, the term chassis means the...
, the transmission
Transmission (mechanics)
A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...
or an axle
Axle
An axle is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to its surroundings, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle...
of the vehicle. Round discs called rotors are attached to the driveline
Powertrain
In a motor vehicle, the term powertrain or powerplant refers to the group of components that generate power and deliver it to the road surface, water, or air. This includes the engine, transmission, drive shafts, differentials, and the final drive...
. A thin air gap is maintained between the rotors and the coils. In normal operation, the rotor turns freely but when electric current flows through the coils, eddy currents are created that apply braking torque to the rotors and therefore to the driveline.