How to operate a Voith hydraulic retarder when descending a long slope?

The Voith hydraulic retarder has five gears, the first gear is a constant speed gear, which is specially set for constant speed downhill, and the second to fifth gears are forced retarding gears, and the braking torque increases sequentially.

  When going downhill, turn the handle to gear 1, which is the constant speed gear, and the Voith hydraulic retarder will record the current speed and go downhill at this speed. If the vehicle speed is less than the recorded vehicle speed during the continuous downhill, the retarder will automatically turn off: if the vehicle speed is greater than the recorded vehicle speed, the retarder will automatically activate. The liquid retarder will automatically adjust the torque from 0-100% according to the change of vehicle speed.

  If the accelerator pedal is pressed down during the downhill process, the retarder will automatically quit working, and after the accelerator pedal is released, the retarder will automatically go downhill at a constant speed recorded when the accelerator is released. For example: when the vehicle speed is 60km/h going downhill, we see the sign with a speed limit of 80km/h in front, we can step on the accelerator to increase the vehicle speed to 80km/h and then release the accelerator, at this time the retarder will start at 80km/h constant speed downhill

  If you need to slow down during the downhill process, you can move the retarder handle to increase the gear step by step, up to the 5th gear with 100% torque, and then turn the retarder to the 1st gear when the speed drops to the required speed . For example: when the speed of the vehicle is 80km/h, and the speed limit of this road section is 60km/h, we can increase the speed of the retarder handle step by step from the second gear, and then turn the handle to the first gear when the speed drops to 60km/h. At this time, the retarder will go downhill at a constant speed of 60km/h.

If the speed of the constant speed gear of the retarder is used, the speed will continue to increase. At this time, pulling the handle to the maximum gear can no longer increase the torque of the retarder. It is necessary to step on the brake to assist the retarder to control the speed of the vehicle.