

A standard oil seal consists of an outer circular metal disk with an inner flexible rubber which is affixed to the metal during vulcanization. The bonded seal has no loose parts to allow leakage of oil or ingress of any contaminants. This kind of seal is more accurate, and can easily be fitted into a smaller space. An example is shown in Figure 2.9.
One of the main principles of power transmission is consistent lubrication. Shaft seals play a hugely important role in this. Imagine a situation involving a shaft-mount reducer – electric motor prime mover, driven by belts, motion controlled by a torque arm – with an improperly seated seal. A blown-out input shaft seal is a nightmare situation, necessitating an entire breakdown and reassembly, not to mention re-aligning and re-tensioning the belts.