Types and installation methods of hydraulic retarders

Retarder history:

Currently there are two main types of retarders for vehicles, one is the eddy current retarder and the other is the hydrodynamic retarder that we often see on trucks.

The first eddy current retarder, born in France in 1936, has a history of more than 80 years.

Eddy current retarder working principle:

Eddy current retarder, using the principle of electromagnetism to convert the kinetic energy of vehicle driving into heat energy to be emitted, so as to realize deceleration and braking.

The advantages of an eddy current retarder are fast response speed, low price, and simple installation. Of course, there are also disadvantages, such as large weight, small braking torque, and high operating temperature. Currently, the proportion of eddy current retarder usage on trucks is already very small, while it is used more on buses.

In 1961, Germany's Voith invented the hydraulic retarder. Initially, hydraulic retarders were used on trains for deceleration before being applied to trucks later.

The working principle of a hydraulic retarder is as follows:

The hydraulic retarder compresses air into the oil storage tank through a proportional valve, and the oil is pressurized into the retarder through the oil circuit to initiate its operation. The rotor drives the rotation of the oil, and the oil moves in the direction of the blades, throwing towards the stator, thus generating a resistance torque against the rotor, impeding the vehicle's rotation and achieving the deceleration effect.

Compared to the eddy current retarder, hydraulic retarders have obvious advantages, including lighter weight, smaller size, higher braking torque, and easier maintenance. However, the main drawback of hydraulic retarders is their relatively higher cost.

Currently there are three main types of hydrodynamic retarders, according to the installation method, namely: series, parallel and independent.

-Series Installation hydraulic retarder

The series installation retarder is installed at the rear end of the transmission, where the hydraulic retarder is connected in series with the gearbox. The power is transmitted through the retarder to the rear axle.

-Parallel installation hydraulic retarder

Parallel installation hydraulic retarder mounted on the side of the transmission (mostly on the left side), hydraulic retarder and transmission for the parallel structure, the power does not need to pass through the retarder can be transferred to the rear axle.

-Independent installation hydraulic retarder

InThe independent installation hydraulic retarder does not need to be installed on the gearbox. It is installed between the gearbox and the rear axle using a separate bracket. The advantage of this design is its wide adaptability to various vehicle models.