By Joyce Laird, contributing editor
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:
*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:
Pillow block bearing units are designed for quick, easy, and safe mounting. They are sealed and pre-greased at the factory making them ready-to-use. Multiple sealing solutions and greases (including food-grade greases) are available for specific application requirements. Some variants may be virtually maintenance-free depending on the application’s operating conditions. Because of the sphered outer ring interface, they can accommodate moderate initial misalignment, but normally do not permit axial displacement. These units offer a simple, cost-effective solution that can provide a number of benefits.
Variants for different applications
They are available in relatively small shaft sizes, from 1/2-in. up to approximately 5-in. They can provide an adequate solution where a more robust product would be excessive. Applications that use these units include:
Food and beverage processing and packaging
Material handling systems
Special machinery (including gym equipment)
“It is important to know the exact application specifications that the bearing will face: the loads, speeds, shaft size, etc.” Goldman says. “How the customer can mount the bearing unit, what the support surface will be, and how they will secure it on the shaft, are also all of equal importance.”
“It is safe to say that most pillow block bearing units are designed for more simple applications. These can be described as applications that don’t place high demands on the bearing. Therefore, whenever the loads are light and the speeds are relatively slow, this type of unit is typically a sufficient choice at a very reasonable price.”