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Definition of a Caster |
Anatomy of a Caster |
Caster Options
Anatomy of a Caster
Construction
There are three basic types of caster construction; stamped, cold forged and hot forged. Stamped construction is used for lighter caster applications. It is a process of cutting and/or bending lighter gauge metal into components. Cold forged construction is used for heavier caster applications. It is a process of cutting, bending or spinning heavier gauge metal into components. Hot forged construction is the process of putting hot metal into a die shaping with continual impact.
Rig/Fork
The rig or fork is the swivel or rigid caster assembly less the wheel. This assembly may or may not include the axle and nut.
Horn/Yoke
The horn is made up of the legs, that surround the wheel, and the base of a swivel caster or the plate or stem of the rigid caster.
Legs
The legs are defined as the axle support brackets that hold the wheel to the caster assembly. The legs are an integral part of the caster horn or they can be welded to the top of the lower raceway thereby creating the horn.
Mounting Plate
The mounting plate or top plate is the flat base, usually with four bolt holes, that completes the top of the caster and allows the attachment, by either welding or bolting to a flat surface.
Mounting Stem
The mounting stem is another way that the caster can be attached. It can be a variety of options; threaded, grip ring, expanding adapter, grip neck, square stock or ferrules.
Stemless
Another type of caster is the stem-less, also referred to as bolt hole or grommet. It does not have a stem or a plate. It has a hole in the top that allows a bolt to go through for attaching.
Kingpin
The kingpin is the rivet or the threaded stud or bolt that attaches the mounting plate or stem to the caster horn, encasing the ball bearings in their raceways. The kingpin holds a swivel caster together. The weakness of the kingpin is side thrust, which causes the kingpins and the casters to fail.
Kingpinless Style
Kingpinless style casters do not have any form of a kingpin. They instead rely on ball bearings encased in an oversized raceway, thus allowing the ball bearings to have more contact area. That contact area is an important component in combating side thrust and shock situations.
Raceway
The raceway is part of the main swivel bearing. This is where the main load of the caster lies. There are two types of raceways, single ball raceway and a double ball raceway. They allow the horn of the caster to swivel in relation to the mounting plate or stem. The single ball raceway is used primarily in light to medium duty applications, while the double ball raceway is used in heavier applications.
Upper/Outer Raceway
The upper raceway is a single roll of balls that allows the swivel horn to rotate in relation to the mounting plate / stem, standard in the single ball raceways.
Lower/Inner Raceway
The lower raceway is the second component in the double ball raceway. It is a single row of balls that ride in a lower raceway beneath the top of the swivel horn.
Swivel Bearing
There are four basic types of swivel bearings, single ball, double ball, single ball and tapered roller, and double tapered roller.
- Single Ball Bearing: A single ball bearing swivel has only one row of balls.
This type of bearing is typically used in lighter applications.
- Double Ball Bearings: A double ball bearing swivel has two rows of balls,
one larger than the other, in both diameter and circumference.
- Single Ball and Tapered Roller Bearing: A single ball and tapered roller bearing
swivel has a single outer row of balls and an inner tapered roller bearing.
- Double Tapered Roller Bearing: A double tapered roller bearing swivel has two
tapered roller bearings, an outer and an inner. This type of swivel design is the best for demanding service.
Axle
There are three types of axles; a solid axle (nut & bolt), a rivet axle and a hollow axle that has a grease fitting on one end for lubricating the wheel.
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