A caster is usually measured by the size of its wheel. For example,
a 4" caster would have a 4" wheel -- even though the
total overall height of the unit is more than 4" tall.
Casters come in two basic types: swivel and rigid. Some people
also call the rigid "fixed" or "stationary."
Axle. The bolt that runs through the wheel and through
the swivel (a.k.a. "kingpin").
Bearing. A bearing is the moving part that allows the
caster to move. It refers to both the swivel bearing (a.k.a.
"raceway") and wheel bearing.
Bolt Holes. The holes in the top plate allowing the
caster to be mounted on the cart.
Bore. The hole through the middle of a wheel. Also a
very tedious person.
Brake. Just like the emergency brake on a car -- when
applied, it helps prevent the wheel from rolling.
Capacity. Also known as load capacity -- the
weight the caster will safely hold.
Caster. A wheel on a swivel, attached under a piece
of furniture or other heavy object to make it easier to move.
The dictionary came up with this definition, not us.
Diameter. The wheel diameter of a caster.
Fastening. The method of mounting a caster to the furniture
or cart (i.e., top plate, threaded stem, etc.).
Hub. The center core of a wheel.
Hub Length. The length of the bore of a wheel. The hub
length is usually wider than the tread.
Kingpin. The axle that holds the fastening to the caster
body and allows the unit to swivel.
Load Capacity. Also known as capacity -- the
weight the caster will safely hold.
Overall Height. The total vertical height of the caster,
from the floor to the top of the mounting plate, or the base
of the stem.
Rigid. A caster that doesn't swivel, but still rolls
forward and back. Also known as a "fixed" or "stationary"
caster.
Stem. A fastening that usually fits into tubing for
the caster to be mounted.
Swivel Lock. Just like it sounds. It locks the swivel,
making the caster act as a rigid.
Swivel Raceway. One or two rows of ball bearings which
bear the weight of the caster and allow the unit to swivel.
Swivel Radius. The horizontal distance from the center
of the kingpin to the trailing edge of the wheel. This determines
the "sweep" of a caster as it pivots -- a good thing
to know to make sure the wheel doesn't strike something as it
turns.
Thread Guard. A small piece of metal or plastic that
fits over the wheel bearing to help prevent threads, dirt, and
other materials from getting into the wheel. Note the spelling
-- thread guard, not tread.
Big difference.
Tread. The part of the wheel that rolls on the ground.
Not to be confused with "thread."
Tread Width. The width of the wheel tread.
