Caster
Terminology
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."
Casters are mounted using fastenings --
usually a plate that is bolted
or welded in place, or a
stem that is inserted nito
tubing. Fastenings are important
because the caster must be
securely fastened to operate
correctly.
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.
