What are Tensioner bearings and Idler Bearings?


How to purchase the right tensioner bearings and idler bearings from a good manufacturer or supplier from China or other countries? How to find a good factory in China. Before, you need to learn about the basic knowledge of tensioner and idler bearings.

This bearing is located at the front of the internal combustion engine. It provides tension to the belt from the crankshaft to the camshaft, air compressor, alternator, water pump, and power steering pump. Due to the continuity of the engine used, it must deal with high temperatures, belt vibration, and high-speed rotation in order to change the direction of the belt. The design of these bearings is different from the specifications of ordinary deep groove bearings.

Tighten the bearing to apply tension to the drive belt and prevent slack. The idler bearing will affect the direction angle change of the belt running, or affect the contact width with the pulley.

Timing belts and auxiliary belts are equipped with idler bearings, and pulleys and brackets are installed on the idler bearings.

Among them, in the timing belt mechanism, sometimes the type with a hole in the inner ring or a bracket for tension adjustment is called a “tension bearing”, and the type without an adjustment mechanism is sometimes called an “idler bearing” “.

The auxiliary idler bearing is also used in the auxiliary drive belt mechanism.

tensioner and idle bearing


  • By adapting them to harsh driving environments and harsh weather conditions, they have improved their ability to prevent penetration of muddy water and dust.
  • Use reinforced resin pulleys with excellent heat resistance and chemical resistance to significantly reduce weight.
  • Reliability can be improved by using materials that work under high-speed rotation and high-temperature conditions (such as seals and grease).


The tensioner and idler bearing are composed of basic components such as inner ring, outer ring, cage, grease, and seals. A pulley can be added to adjust the rotation ratio. You can add a bracket to adjust the position to increase tension. The race is one of the components of the bearing. It has a groove track that allows the ball to be positioned. Outer race and inner race formed a set. The inner seat ring is located on the subassembly, and the outer seat ring is located on the housing. A pulley can be added to the outer ring to provide a timing belt system with a designed speed. The rolling element is the “ball” that runs between games. The retainer moves with the ball, holding the single ball in place. Grease also has an important role in reducing friction, and the oil seal can hold the grease and prevent foreign matter from entering.

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