By Joyce Laird, contributing editor

Pillow block housings typically have two bolt holes for mounting to a support surface with threaded fasteners. The bolt holes vary for different housing designs and materials. SKF pillow block bearing units are available as standard in a wide variety of designs and materials.

Cast iron is the typical pillow block housing material. They usually have oblong bolt holes (fig. 1) for ease of setting. Cast iron pillow block housings provide adequate support for a range of applied loads and enable the bearing units to be relubricated through a grease fitting. This makes them especially suitable for bearing arrangements that operate under any of the following conditions:

high levels of contamination
high speeds
high temperatures
relatively heavy loads

Composite pillow block housings (fig. 2) are made of lightweight glass fiber reinforced PA6. For durability, mechanical strength and thermal stability, these units are reinforced with a “molded in” steel coil and the two oblong attachment bolt holes are reinforced with zinc-coated steel inserts. Composite pillow block units are particularly well-suited for applications with relatively high speeds, moderate loads and where reliability and minimal maintenance are key factors.

Pressed steel pillow block housings (fig. 3) are made of sheet steel and are zinc-coated for corrosion protection. They are designed for simple applications with limited loads and speeds. These housings have no relubrication feature.

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