Pillow blocks are a special design of bearing units or housings of a housing unit.  Like all housing units, bearing units or also radial insert ball bearing units, they consist of a insert (deep groove ball bearing sealed on both sides) and a housing, in this case a pillow block housing.


The design with a crowned ball bearing and a hollow ball-shaped pillow block housing compensates for slight misalignments. The pillow block is fastened to the shaft for example with set-screw lockings. For this purpose, the inner ring of the pillow block is fixed to the shaft with set screws or grub screws (series: UCP, UCPA, UCPH). Another fastening option is fixing on the shaft with an eccentric collar locking (series: KHP) or by means of an adapter sleeve locking (series UKP).

Areas of application

Pillow blocks are used to support shafts in all areas of mechanical engineering. They have a machined base with two mounting holes and are screwed onto a flat surface and are particularly suitable for horizontal mounting. Pillow blocks offer the highest load capacity of all housing types.

Technical basics pillow blocks

In principle, the technical basics of bearing units also apply in full to pillow blocks, since pillow blocks are a special form of bearing units. Information on tolerances, lubrication, fits, mounting on the shaft, etc. is stored in the Knowledgebase under bearing units. Further information is also available in the maintenance and operating instructions and under FAQ.



The ASK and ASAHI pillow blocks are available in the following designs:


The housing P in combination with an insert results in the respective series e.g. UCP 200 = pillow block made of cast iron with set-screw locking . The same applies to the other pillow block housings, e.g. UCPH 204, UCPA 205, UCPW 208, etc.

Housing materials

The pillow block housings are made of gray cast iron as standard. Stainless steel, PBT thermoplastic and zinc die casting are other materials used. The bearing inserts are made of steel or stainless steel, depending on the design.

Another material is galvanized sheet steel. This design is lighter and more filigree than the cast housing units. Here, only the fixing with grub screws (as locking screw) is available.

Possible combinations

of pillow block housings and radial insert ball bearings


Use as floating bearing or locating bearing

Pillow blocks are often used horizontally and as non-locating bearings. If a shaft is supported by two pillow blocks, the fit on the shaft is not identical due to manufacturing tolerances and longitudinal elongations of the shaft. These deviations can be compensated for by using the bearing as a non-locating bearing, i.e. the shaft can be displaced and / or the radial insert ball bearing can be tilted.

When used as a locating bearing, the inner ring is firmly connected to the shaft, either with grub screws, eccentric ring or adapter sleeve. The locating bearing guides the shaft axially and transmits external axial forces. When more than two pillow blocks are used on the shaft, only one is used as a locating bearing in order to avoid axial distortion.

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Bearing units