General

Capacity - The maximum load per caster or wheel recommended for intermittent operation over smooth floors at speeds of 3 mph. or less. (Gross weight should be divided by the number of casters or wheels on which it 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.

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.

Face - The width of the wheel tread cross-section, measured at the base o the tread rather than at the point of floor contact.

Horn - The caster part which comprises legs, plus a base (horn base of swivel caster or mounting plate of rigid).

Horn Base - The flat part at the top of the horn 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.

King Pin - A rivet, or threaded stud or bolt with nut, that holds the mounting plate and horn assembly of a swivel caster together. Forged as an integral part of mounting plate on higher quality casters for maximum rigidity and strength.

King Pin Nut - The nut on the bottom of a threaded king pin or bolt that permits the disassembly or adjustment of swiveling components; a maintenance feature of better casters not found with rivet type king pins.

Legs - The axle support brackets extending down from the horn base of a swivel caster, or from the mounting plate of a rigid caster.

Main Load Bearing - The row of steel balls or rollers that swivels the horn 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 ittachment by bolting or welding to :lat surface.

Offset - (swivel lead) The perpendicular distance between the vertical centerlines of the king pin an the axle of a swivel caster. Larger offsets afford easier swiveling, shorter offsets greater strength.

Overall Height - The vertical distances from the top of the caster mounting plate to the bottom of the wheel.

Raceway - A surface in which bearing balls or rollers rotate,

Retaining Washer - A steel washer pressed into the hub ends of some roller bearing wheels to hold the bearing in place.

Rig - A swivel or rigid caster assembly less wheel, that may or may not include axle, nut or spanner bushing.

Rockwell C - System for measuring hardness of metals.

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

Secondary Load Bearing (Commercial) - The row of steel balls that rides in the raceway between the horn 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 Bearing (Precision) - A precision self contained bearing, usually a tapered roller bearing, operating between the horn base and the king pin 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.

Swivel Radius - The horizontal distance from the centerline of the caster king pin to the outer edge of the wheel (a measure of clearance required to swivel a caster 360).

Thrust Washer - A steel washer between the hub ends of the wheel and the inside of the caster legs.

Yoke - Alternate term for horn.

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Wheel Bearings

	Ball Bearings The standard ball bearings referred to in this catalog are the unground radial type, radial type, intended for light to medium duty service.  On special order we can supply light or heavy duty precision ball bearings for both redial and thrust loads, in configurations including flanged, sealed, square bores, extended inner raceways and wide inner raceways with self-locking collars.
	Delrin (Registered DuPont trademark.) Sometimes referred to as plastic or celcon.  For environments Detrimental to metal bearings, acetyl resin bearings offer chemical and corrosion resistance.  Delrin is a standard offering in certain wheels, as either a sleeve or flange type bearing.  Plastic bearings can be custom machined and installed in most other wheels on request.  Note: flange type bearings extend actual hub length of wheel approximately 3/16.
	Plain Bore The term applied to running machine bored wheels, directly on an axle; hence, the absence of a bearing.  Suitable for light or seldom moved loads, where ease of starting and rolling is not too important or where price is a dominant factor.  Except for roller bearing bores, we normally machine “plain bore� wheels 1/64� oversize for good running fit.  Closer tolerance machining available at extra cost.
	Precision Ball Bearings This type of bearing consists of a hardened outer raceway and inner raceway, separated by a concentric ring of hardened steel balls.  This bearing is used in pairs and is usually press fitted into a deep pocket of a wheel that has high load, and high speed capabilities.  This type of bearing is primarily used to carry radial loads only.
	Roller Bearing Most popular anti-friction bearing for industrial equipment.  Consists of a cage-type roller assembly, and an outer race that may be separate or integral see on page 103.  We most often use hardened and ground steel roller bearings for maximum loads and life.  (Note: plastic retaining washers or other components may be used unless we are advised of a high-heat application.)
	Self Lubrication A sleeve, usually of sintered iron or oil-impregnated bronze, is press-fit into the wheel bore.  Lacks the ease of movement anti-friction bearings provide, but practical for light loads where re-lubrication is a problem.  (A light application of oil or graphite improves rollability and extends bearing life.)
	Tapered Bearings Ideal for heavy duty caster applications because their tapered faces will handle any combination of downward and side forces.  Used in various swivel assemblies as well as in wheels.  Two bearings are installed per wheel, one in each side of the hub, consisting of a cup (hardened and ground outer raceway) and cone (roller assembly).  Spanner bushings are not employed since adjustment requires tightening caster legs against the bearing assembly.  Tapered bearings extend overall hub length of the wheel itself by approximately ¼�.