Hydraulic release bearing is an important part of the clutch system. It gives the driver more comfort in operation of the clutch, especially during gear change.

It’s an important part of the clutch system. It gives the driver more comfort in operation of the clutch, especially during gear change.

Hydraulic release bearing is used in all manual transmissions and motorbike transmissions with wet clutches. The idea behind it is similar to that of brake servo control.

Hydraulic release bearing is a flexible bearing without spring action. It is driven by the hydraulic pressure generated from the clutch master cylinder. A reservoir can be added to prevent air bubbles from entering the system.

The release bearing contains a bearing body and a bearing sleeve. The bearing sleeve is pressed over the bearing body and held in place by a circlip. The bearing body is pressed into a thrust bearing housing, and clamped to it by means of an adjusting bolt which has a locknut fitted. A dust cover is fitted to the end of the bearing body, which projects from the clutch housing, and , in addition, an oil seal or O-ring may be used between this cover and the clutch housing.

When you press and hold the clutch pedal with your foot, it will push against the master cylinder piston. By pushing the piston, it generates hydraulic pressure in fluid inside. The fluid then pushes on a piston in the release mechanism, causing it to force a fork that moves along a shaft on which the throw-out bearing pivots or slides. When this happens, it disengages two plates of friction material that are normally pressed together by means of pressure plate springs so they can move apart, disengaging them from contact with each other and thus disengaging power transmission between engine and gearbox. This in turn allows you to shift gears while engine speed remains constant.

The release bearing supports the driver at high speeds or during longer gear changes and guarantees smooth engagement of the clutch and optimized shift comfort. Therefore hydraulic release bearing is used in all manual transmissions and motorbike transmissions with wet clutches. The idea behind is similar to that of brake servo control – transmission of driver power from pedal to master cylinder by means of hydraulic medium (clutch fluid).