Hydrodynamic bearings work by having a film of fluid separating the sliding surface (shaft/journal or runner) from the bearing surface. The hydrodynamic lubrication theory explains that pressure develops in this film when the oil film is squeezed by the sliding surface over the stationary surface in the direction of rotation. The fluid film provides stiffness and damping to the rotor-bearing system.

  • Journal applications are those where the rotor is to be laterally supported by a bearing.
  • Thrust applications are those where the rotor is to be axially supported by a bearing.

Fixed geometry thrust bearings such as a plain (or bumper) and taperland are popular for relatively low load applications. In many cases these are combined with journal bearings to make a combination journal/thrust bearing. We design and manufacture both plain and taperland thrust bearings.

Tilting pad thrust (TPT) bearings, as the name implies, have variable geometry wherein the bearing surface is able to tilt perpendicular to the plane in which the sliding surface moves. This allows for higher load carrying capacity than fixed geometry bearings.

D&S Engineered Products makes two types of tilting pad journal bearings - Rocker Back TPT and Pliant Support TPT.

Rocker Back TPT

TPT rocker Rocker Back TPTBs were first introduced almost a century ago. It is produced by assembling a set of thrust pads onto the face of a carrier. The pads have a line or point pivot below the pad so the pads can "rock" on the carrier. Retainers assembled between the pads retain the pads over the carrier.

Pliant Support TPT

TPT pliant Pliant Support TPTs are a relatively new design. The underside of the pad does not have line or point pivot but has a cylindrical column supporting the pad. The pivot is elastically pliant and it allows the pad to tilt under load. The pads are fastened onto the carrier. The assembled pads are processed so that the bearing surface of all the pads is brought into the same plane. This significantly increases the load sharing between the pads. This design provides significant advantages over the rocker back TPT design in some applications.

In theory a hydrodynamic bearings with a full film of fluid between the bearing and the runner will have infinite life. The key to infinite bearing life is a "full" film. However, in many challenging applications, the film is not "full" and the bearing is subject to failure if the bearing and runner come in contact. In these applications, the material interface of the bearing and the runner becomes very important. We have developed material pairs to help in these type of applications. Please see our page on bearings for demanding applications.