A thrust bearing is used to support the axial load on the rotor. It consists of a collar surface attached to the rotor, bearing pads and bearing base. Bearing pads can be rigidly connected to the bearing base or can be allowed to undergo certain motion relative to it. A lubricant is supplied between the collar and pads to avoid dry friction conditions and to reduce the frictional losses. Generally, the pads are arranged in such a way that there is a converging gap between the pad and the collar surface. This helps in generating the pressure in the fluid film due to the relative motion between the pad and collar. The pressure essentially keeps these surfaces separated. If the pressure is not sufficiently high, the surfaces will come into direct contact with each other. Due to the different requirements in different applications there are many types of thrust bearings in common use. The initial film thickness profiles for some of the commonly used thrust bearings are discussed in the upcoming sections. Note that the profiles are defined in the local coordinate system. Figure 7-17 shows the definition of the local coordinate system.