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CASTER
: A caster represents an assembly,
wheel, wheel bearings, thread guards, axle, and nuts, all of which are assembled
together as one complete unit. There are two basic types of casters.
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SWIVEL CASTER:
Consists of all of the components of the caster as well as a raceway which
contains balls or bearings that allow the caster to swivel.
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RIGID CASTER: Or stationary
caster, consists of all of the components of the caster but does not have a
raceway. (It therefore can roll only in two directions, in a straight
line).
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SWIVEL
RADIUS: Distance measured horizontally from the
center of the kingpin to the trailing edge of the wheel. The
kingpin is the pin in the center of a plate caster that holds the plate to
the wheel forks. On a stem caster, the radius is from the trailing
edge of the wheel to the center of the mounting stem.
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TREAD WIDTH:
Width of wheel at the point of contact with the floor.
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CASTER SIZE:
Determined by wheel diameter. For example if you ask about a 6"
caster, we assume you are talking about a 6" wheel even thought the caster
overall height will be 7" to 7-1/2".
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OVERALL HEIGHT:
Vertical distance from the floor to the top of the mounting plate or the top
of the swivel raceway for a stem caster.
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FRICTION or CAM BRAKE:
Stops (or slows) the wheel by applying pressure from the side between the
wheel and the forks. Not the most positive type brake, but
relatively cheap and works in many applications.
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TOP LOCK BRAKE:
Bake petal is normally on the side of the caster, but sometimes on the top
below the plate or stem mount. Petal engages a pad that clamps
down on the wheel for a very positive lock. Since the pad is metal,
this brake can be less effective when used with a metal wheel. This
brake is sometimes referred to as a Tread Lock Brake.
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TOTAL LOCK BRAKE:
Engaged via a petal that when depressed locks the wheel and the swivel
section of the caster. Very positive braking action, but cost
more than other types of brakes. With the wheel and the swivel
locked down, the caster becomes a foot with no movement.
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SWIVEL LOCK OR DIRECTION
LOCK BRAKE: Usually has
a pin that pulls out and when inserted back into the swivel section,
prevents the caster from swiveling. This turns a swivel caster
into a rigid caster. Normally has 4 positions to lock the swivel
at 90 degree offsets. Very useful for some applications and can
be combined on some casters with a top lock brake. Also called a
"Position Swivel Lock" at times.
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SIDE LOCK BRAKE:
Another name used for both Friction Lock and Top Lock Brakes when the brake
petal is on the side of the caster.
The above is a very basic description of a caster.
There are many styles of casters and not all will easily fit the basic
description. |