Buying Guide


How to Select The Proper Caster and Wheel

There is no simple formula or rule that can be followed in selecting the proper casters. Many varying and individual factors must be balanced to make the selection that will do the best job for you. The following are several of the more important considerations.

Load Weight. The heavier the load, the larger the wheel required for the caster. The weight of the load also influences the mobility of the wheel. Roller or ball bearings are recommended for loads over 400 pounds. Weight capacities are shown for each caster in this catalog.

Floor Conditions. Make sure the wheel you select is large enough to pass over cracks in the floor, tracks, moldings and other obstructions. For floor protection on linoleum, tile, carpet, etc., use polyurethane or Performa rubber wheels.

Unusual Conditions. Each wheel material has certain characteristics which will give the best results where unusual conditions exist. For example, where acids, oils, chemicals and other conditions harmful to rubber are present, Colson polyurethane, polyolefin, Maxim, phenolic or steel wheels are recommended. Check conditions, then select caster and wheel.

Rolling Ease. The larger the wheel diameter, the easier it rolls. Roller bearings carry heavier loads. Ball bearings roll easier but carry lesser loads. When possible, use the largest ball bearing wheel for best results.

Extreme Climates. Room temperatures are no problem for most casters. But extreme cold or heat can be a problem. Colson helps solve this problem with “Colson 45”... the green lube which assures caster rolling ease from 45°F below zero to 260°F above. It’s standard on all Colson casters. (Note: Some wheel types should not be used in extreme temperature ranges. Consult factory).


Caster Types

Rigid A rigid Caster has a rigid yoke and wheel assembly which permits only straight-line movement.

Swivel A swivel caster has a swivel yoke and wheel assembly that will allow rotation of 360 degrees, which permits movement in any direction.

Locking A locking caster is an assembly that can be locked in place by some sort of mechanic device.


Application Guide

The chart below is designed to provide you with a general comparison of Colson wheel types under a variety of floor surfaces and operating conditions. For specific applications or unusual conditions, please consult factory.



Glossary of Caster and Wheel Terms

Caster Parts Definitions & Nomenclature:

Axel Nut The nut on the side of the leg that holds the thrust washers, spanner bushings, and bolt or lube axles together.

Caster/Castor 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.

Fork/Horn/Yoke The caster part which is comprised of legs plus a base (fork base of swivel caster or mounting plate of rigid).

Kingpin 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 casters

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.

Legs 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 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 casters 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 caster and permits attachment by bolting or welding to a flat surface.

Raceway A surface in which bearing balls or rollers rotate.

Rig A swivel 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 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 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.

Wheel 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.

Caster Parts Dimensional Definitions & Nomenclature:

Bolt Hole Spacing Bolt hole spacing is the distance measured from the center of the bolt hole to the opposite center of the other bolt hole.

Bore Diameter Bore diameter is the distance measured through the center of the wheel.

Capacity The maximum recommended lad per caster or wheel based on intermittent operation over smooth floors at speeds not exceeding 3 m.p.h., with no shock loading or adverse environmental conditions. *Gross weight of a truck or dolly should be divided by the number of casters or wheels on which the weight is distributed.

Caster Size A loose term for classifying casters, based on the nominal diameter of the wheel. For example, a “6 inch caster” is any caster having a 6 inch diameter wheel.

Hub Length Hub length is the widest part of the hub (including bearing assembly and thread guards).

Offset/Swivel Lead The perpendicular distance between the vertical centerlines of the kingpin and the axle of a swivel caster. Larger offsets afford easier swiveling, shorter offsets greater strength.


Overall Height Overall height is the vertical distance between floor and mounting plate. (NOTE: Casters with threaded stems are measured to the top washer and do not include the length of the threaded stem).

Plate Dimension Plate dimension is the measured distance from one edge of the top plate to the opposite side and the distance from the other edge of the top plate to the opposite side.

Swivel Lead Swivel lead is the horizontal distance between vertical centerlines through kingpin and wheel center.

Swivel Radius A swivel radius is the horizontal distance from vertical centerline of kingpin to outside edge of wheel tread. Specifies minimum clearance required for mounted caster to swivel 360 degrees.

Tread Width/Face The outer surface of the wheel, in contact with the ground. The width of the wheel tread cross-section, measured at the base of the tread rather than at the point of floor contact.

Wheel Diameter Wheel diameter is the outer nominal diameter of the wheel.

Caster Measurement Definitions & Nomenclature:

Component Thrust Designates side forces exerted on a swivel caster and properly counteracted by the secondary load bearing.

Direct Thrust Designates those downward forces exerted on a caster by the load, and counteracted by the main load bearing.

Durometer A measure of the hardness of resilient tread wheels.

Rollability Ease of starting and rolling, measured by drawbar pull. This is determined by load, floor conditions, and type and size of wheels and bearings.

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