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Swivel Caster

Caster Parts Definitions:

By Dina

Axel Nut

One of part Swivel Caster is the nut on the side of the leg that holds the thrust washers, spanner bushings, and bolts or lubes axles together.

Swivel of the Swivel Caster

A pivoting roller attached to the bottom of furniture or trucks or portable machines to make them movable.

Cotter Pin

A small metal pin used to keep other parts from changing their position, such as to keep a nut from turning, fastened in place by spreading apart its ends after it is inserted

Fork Base

The flat part at the top of the fork from which the legs extend. Serves as lower raceway for main load bearing, and may provide a seat or upper raceway for secondary load bearing.


The caster part which is comprised of legs plus a base (fork base of Swivel Caster or mounting plate of rigid).


A rivet, or threaded stud or bolt with nut, that holds the mounting plate and fork assembly of a Swivel Caster together. Forged as an integral part of mounting plate on higher quality Swivel Caster.

Kingpin Nut

The nut on the bottom of a threaded kingpin or bolt that permits the disassembly or adjustment of swiveling components; a maintenance feature of better casters not found with rivet-type kingpins.


The axle-support brackets extending down from the fork base of a Swivel Caster, or from the mounting plate of a rigid caster.

Lube Bolt Axle

An axle used to attach the wheel to the fork legs of a Swivel Caster, containing a lubrication hole allowing for lubrication of the spanner bushing without disassembling the wheel from the fork legs.

Lubrication Fitting

A fitting place into higher quality Swivel Caster that allows for lubrication of the bearings without disassembling the fork base, main, and load bearings.

Main Load Bearing

The row of steel balls or rollers that swivels the fork base in relation to the mounting plate of a Swivel Caster, and counteracts direct thrust.

Mounting Plate

The flat base, usually with four bolt holes, that forms the top of a Swivel Caster and permits attachment by bolting or welding to a flat surface.


A surface in which bearing balls or rollers rotate.


A Swivel Caster or rigid caster assembly less wheel that may or may not include axle, nut or spanner bushing.

Secondary Load Commercial/Industrial Bearing

The row of steel balls that rides in the raceway between the fork base and secondary bearing retainer of a Swivel Caster to counteract component thrust. It is this bearing that characterizes the popular “double ball race” caster.

Secondary Load Precision Bearing

A precision self contained bearing, usually a tapered roller bearing, operating between the fork base and the kingpin of a Swivel Caster. Constitutes the most efficient means of assisting Swivel Caster action by counteracting component thrust.

Spanner Bushing

A non-rotating sleeve of seamless steel tubing that fits over the axle in many casters. Serves the dual purpose of providing a smooth inner raceway for the wheel bearings, and strengthening the caster by permitting the legs to be tightened against it.

Standard/ Solid Bolt Axle

An axle used to attach the wheel to the fork legs of a Swivel caster.

Thrust Washer/Retaining Washer/Combination Seal

A steel washer between the hub ends of the wheel and the inside of the caster legs. A steel washer pressed into the hub ends of some roller bearing wheels to hold the bearing in place.


A round structure, solid disk or a rigid circular ring that is designed to turn around a center, normally an axle passed through the center of the structure. Caster wheels come in a wide variety of materials, sizes and treads. Often Caster wheel type is synonymous with the material makeup or specialized tread pattern exhibited by the wheel.

Fore more information see about Office Chair Casters, Threaded Stem Caster, Stem Caster and Chair Casters