Retarder braking system

RETARDER BRAKING SYSTEM

Breaking the truck generates high amount of pressure,wear and heat on the brake disks and brake pads and in some cases,continuous braking during downhill or in traffic leads to the decrease of brake pressure,The truck needs to halted in safe place to recharge the compressor. The best solutions for these safty less conflicts is the RETARDER BRAKING SYSTEM.

The reatarder brake system gives the smooth braking experience with no energy loss,wear,noise while slowing down the heavy loaded trucks.It saves the maintainance cost on replacing the brake disks,linings and brake pads.

HOW RETARDER WORKS?

Retarder is a hydraulic system that is integrated into the output end of a truck’s gearbox and uses high-pressure oil as a braking medium Via a gear transmission, the Retarder acts on the output shaft of the gearbox and thus directly on the propeller shaft.

Once the Retarder is applied, it generates a braking force on the propeller shaft corresponding to up to 500 kW, depending on the propeller shaft speed and the applied braking torque. This is about two to three times more braking power than can be delivered by the engine brake. The lever on the steering column controls Retarder braking in five steps(depending on truck manufacturer) of increasing brake power,These input is sensed by the electronic controll unit and makes function the retarder.

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The retarder is driven by a step up gear train,The rotor is mounted on a shaft equiped with a gear,These retarder side gear is connected to the transmission side gear(output shaft of transmission)directly in 2:1 gear ratio.It also contains a fixed stator.when the retarder is activated, the oli sump in the retarder brake unit is supplied with the compressed air.These oil moves through the inlet throttle and then to the retarder circuit in these circuit it moves into the rotor and to the fixed stator.The rotor acclerates the oil and builds up breaking torque,the stator redirects the oil to the rotor, which decelerates the rotor and via the gear connected to the rotor creates retardation on the output shaft and thus the vehicle decelerates.

Simple working principle of retarder.

The kinetic energy from the vehicle during braking is converted into heat and it is dissipated into the oil.These oil is then cooled by the vehicles cooling system or by heat exchangers.

NOTE : The retarder does not bring the vehicle to complete stop but it has its adverse effect on slowing the vehicle.however,the conventional braking system is used for the complete stop of the vehicle.

Working principle of hydraulic retarder.

A simple retarder uses vanes(rotor) attached to a  output of the drive shaft between the clutch and roadwheels. They can also be driven separately via gearsoff a driveshaft. The vanes are enclosed in a static chamber with small clearances to the chamber's walls (which will also be vaned), as in an automatic transmission. When retardation is required, fluid (oil or water) is pumped into the chamber, and the viscous drag induced will slow the vehicle. The working fluid will heat, and is usually circulated through a cooling system. The degree of retardation can be varied by adjusting the fill level of the chamber.

Hydraulic retarders are extremely quiet, often inaudible over the sound of a running engine, and are especially quiet in operation compared to engine brakes.

Elecectric retarders.

They use electromagneticinduction to provide a retardation force. An electric retardation unit can be placed on an axle or drive lineand consists of a rotor attached to the axle, transmission, or driveline—and a stators securely attached to the vehicle chassis . There are no contact surfaces between the rotor and stator, and no working fluid. When retardation is required, the electrical windings in the stator receive power from the vehicle battery, producing a magnetic field through which the rotor moves. This induces eddy current in the rotor, which produces an opposing magnetic field to the stator.It slows the rotor and hence the vehicle

Highlights

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📌simple operation.

📌increased effeciency.

📌low maintanance cost.

📌Retarders serve to slow vehicles,or maintain a steady speed while traveling down a hill. 📌helps in better controll and stability of vehicle during down hill.