Whether you are looking at Albion casters or a different brand, all of these wheels will have similar anatomy to meet safety regulations. Here is an overview of everything you need to know about the anatomy of casters. 

Kingpin Bolt

Unless they are Kingpinless, all caster types will have a Kingpin bolt. This is designed to hold the caster together. In heavy-duty models, this may be replaced with a Kingpin rivet. 

Top Plate

The top plate is used to attach a caster to a piece of equipment. It is often a horizontal plate of metal. Heavy-duty models will have the Kingpin bolt integrated into this piece. The rest of the standard types will have a hole for the Kingpin bolt to go through. Kingpinless models will have a flat plate. 

Load Ball Bearing

The load ball bearing is found on swivel models. It is a group of steel balls that let the yoke base swivel. 

Yoke Base

This is the flat part found on the top of the yoke. It is what the legs attach to. 

Thrust Ball Bearing

A thrust ball bearing is another row of balls that adds to the stability and movement. It is typically only found on medium and lightweight models. 


This is found on medium and lightweight models and forms the track for the thrust ball bearings. It is designed to keep them in place. 


The nut attaches to the Kingpin bolt and keeps the swivel raceway in place. It is found on most standard models. 


Legs are the metal extensions that hold the wheels in place. They will have holes in them for the wheel axle to go through. 

Axle Bolt

The axle bolt is what the wheel revolves around. It goes through the hole on the legs to attach the wheel to the caster. 

Axle Nut

The axle nut is what holds the axle bolt onto the yoke. Without it, the axle would detach from the legs, and the wheels would fall off. 

Retaining Washer

The retaining washer is found on heavy-duty models. It is necessary to help keep the bearings in place and is also designed to lower the amount of maintenance a caster needs. 

Spanner Bushing

The spanner bushing can be found on heavy-duty models. It is a small tube that slips over the axle bolt to reinforce it when the wheels are loaded. 

There are many different types of casters on the market. Fortunately, they all have similar anatomy that is easy to understand. 

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