Pillow block bearing unit is a bearing unit that combines a rolling bearing with a bearing housing. Most pillow block bearings are made of spherical outer diameter and are installed with pillow block which have spherical inner holes. They have various structural forms, good versatility and interchangeability.

The design of the UCPA series ball Bearing unit also has a certain degree of self-aligning, easy to install, with double structure sealing device, which can work in harsh environment. UCPA bearing block is generally cast. Other common types of bearing housing are UCP, UCF, UCFS, UCFC, UCFL, UCT etc.

Pillow blocks can refer to a variety of bearing styles such as single row ball bearings, double row ball bearings, spherical roller bearings, taper roller bearings, etc. A unit is typically a reference for a 1-piece housing as opposed to a split housing. For simplicity, this article will focus on single row ball bearing units.