Collar bearings for gear pumps

Collar bearings

In contrast to normal friction bearings without a collar, which are used in chemical pumps, for example, the collar bearings are constructed somewhat differently.

There are different designs that are used depending on the application.

Essentially, a distinction can be made between two variants of the attached collar. There are collar bearings that are made from one piece, where the collar sits directly on the bearing body, and there are collar bearings where the collar is bolted separately to the front of the bearing. The use depends on the application and the process.


When is a screwed collar used?

A screwed-on collar is usually used with larger friction bearings. The advantage of this is that it is easier to manufacture because the workpiece from which the bearing is made is much smaller.

At WITTE, collar bearings are used in pumps for polymer production and processing. This applies to the EXTRU, BOOSTER and POLY series. The reason is the high suction pressures of the EXTRU and BOOSTER pumps. With the large POLY pumps, collar bearings have the advantage that during start-up (when low speeds and low pressure are present) the face of the bearings does not touch the teeth, as there is always a minimum axial clearance. ​​​​​​​

How does a collar bearing work?

With medium-lubricated collar bearings, the lubrication flow is directed through the lubrication grooves to the outside of the housing and flows back into the main product flow via a V-groove in the cover. The collar ensures that the bearing is not pressed axially in the direction of the gear shafts in the event of negative differential pressure (for example in the start-up process for melt pumps in extrusion).

The use of the collar bearings guarantees a sufficiently large axial clearance in every operating condition, in the start-up process as well as during operation at high pressures or temperatures.

In addition, the bearings are fixed in the housing so that a change of the bearing position, for example due to vibrations during transport, is impossible.

Other bearing technologies