Belt tensioner is located in the front of an internal combustion engine. It provides tension to the belt which drives from the crankshaft, to the cam shaft, alternator, air compressor, power steering pump, and water pump. It must handle high temperatures, high-speed rotation, and belt vibration because of contiguity in the engine used in order to make the direction of a belt change. These bearings are designed against different specification from normal deep groove bearings.