Casters 101

How to Select the Proper Casters and Wheels for Your Application

Many factors must be taken into consideration in order to select the proper industrial caster or wheel. To make the most appropriate selection for your application, consider the following:

Load Weight – The heavier the load, the larger the wheel required for the caster. The weight of the load also influences wheel mobility. For heavy duty loads over 400 lbs., roller or ball bearings are recommended.

Floor Conditions – Be sure the wheel selected is large enough to pass over cracks in the floor, tracks, molding, and other obstructions. Use polyurethane or Performa rubber wheels for floor protection on linoleum, tile, carpet, etc.

Unusual Conditions – Each wheel material has characteristics which will provide the best results where unusual conditions exist. For example Polyurethane, polyolefin, phenolic, or steel wheels are recommended where acids, oils, chemicals, and other substances harmful to rubber are present.

Rolling Ease – The larger the wheel, the easier it rolls. While roller bearing wheels can carry heavier loads, ball bearing wheels roll more easily but carry lighter loads. Whenever possible, use the largest ball bearing wheel necessary for best results.

Extreme Climates – Room temperatures are not a problem for most casters. However extreme cold and heat can be a problem. Bastian Industrial Engineering Technology casters come standard with lubrication designed to withstand temperatures from 450A�F below zero to 2600A�F above zero.

Shock Load – The impact caused by dropping a load on a cart or truck, or by rolling on a rough surface. When encountering shock loading, you will need to look at four things: construction of the caster, type of kingpin, swivel bearing, and the composition of the wheel.

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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.

Caster Parts Definitions & Nomenclature

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

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.

caster Size – A loose term for classifying casters, based on the nominal diameter of the Getting An Electrical Apprenticeship 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).

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).

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

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.

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.

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Capacity – The maximum recommended lad per caster or wheel based on intermittent operation over smooth floors at speeds not exceeding 3 mph, 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.

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.

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.

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

Caster Measurement Definitions & Nomenclature

Durometer – A measure of the hardness of resilient tread wheels.

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

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

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