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.

“A basic pillow block bearing unit is typically an insert bearing which is based on a sealed deep groove ball bearing and a one piece housing.” Joshua Goldman, Applications Engineer for SKF USA says. These units consist of:

*an insert bearing which is based on a sealed single row deep groove ball bearing in the 62 series with a spherical (convex) outside diameter surface and an extended inner ring:*a one-piece housing made of several different material options which include but are not limited to cast iron, cast stainless steel, and composite. The housing has a correspondingly sphered but concave bore