Bearing internal clearance before installation (original space) and time after installation to reach operating temperature within the bearing clearance (known as work space) is different from the former large, with different applications, many requests to run a negative gap, that is, applied load, the pre-load is to ensure that when used with the bearing load conditions prevent slipping and damage.

Main role: to improve the bearing stiffness and reduce operating noise, wear compensation operation by increasing the gap and improve the accuracy of the shaft guide, for extended bearing life.
Pre-pressure is often the main target (dynamic load rating Cr) coefficients, the best pre-press needs to first calculate the pre-load pressure, confirmed by testing to determine the normal value continuously revised through different methods of implementation of the regulation.