Bearings - Design, Friction, Lubrication, Bearing Metals #231870

A journal should be designed of such a size and form that it will run cool, and with practically no wear. The question both of heating and wear is one of friction, and in order for us to understand the princi ples upon which the design of bearings should be based, we must first understand the underlying principles of friction. Friction is defined as that force? Acting between two bodies at their surface of contact, when they are pressed together, which tends to prevent their sliding one upon the other. The energy used in overcoming this force of friction, appears at the rubbing surfaces as heat, and is ordinarily dissipated by conduction through the two bodies. The force of friction, and hence the amount of heat generated under any given circumstances, can be greatly reduced by the introduction of an oily or greasy sub stance between the rubbing surfaces. The oil or grease seems to act in the same way that a great number of minute balls would, reducing the friction and wear, and thus preventing the overheating and couse quent destruction of the parts. On this account, bearings of all kinds are always lubricated. Thus the question of journal friction involves the further question of lubrication.