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GLOSSARY OF TERMS

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A

ASSEMBLY. Usually refers to a castor from which the wheel, axle material and any optional fitting has been removed.

B

BRACKET. See assembly.

C

CASTER. U.S. spelling of castor 

CASTORS consist of a wheel fitted into swivelling or non-swivelling (fixed) forks. The wheel is usually retained between the castor forks using a simple axle set.

D

E

F

FABRICATED STEEL CASTORS usually consist of precision machined heavy steel forgings housing combinations of tapered roller or ball bearing races. The forks a re usually securely welded to the swivel head forging giving an extremely strong construction suitable for heavy loads.

FITTED HEIGHT. The height by which a piece of equipment is raised byfitting a castor. In the case of certain fixing types (eg expanding tube adaptor) this is not necessarily the overall height of the castor. 

FIXED CASTORS consist of a wheel mounted between the forks of a non-swivelling housing.

FORKS. The part of the castor into which a wheel may be fiitted in conjunction with an axle set.

G

H

HEADED SPACER. The component of the axle set on which a ball bearing wheel runs when fitted into a castor.

HOUSING. See assembly.

I

J

K

KING PIN. The component of a swivel castor which usually secures together the separate swivel head and fork pressings.

L

LOW LEVEL CASTORS are characterised by a high load in relation to overall height and typically are fitted with wide tread or twin wheels.

M

N

O

OFFSET. In a swivel castor, the horizontal distance between the centre of the wheel axle and the vertical axis of the swivel head bearing.

P

PRESSED STEEL CASTORS incorporate a single or double ball bearing swivel raceway construction. The balls run in tracks formed in the fork and top plate pressings which are secured together by a heavy rivet or bolt acting as a king pin.

Q

R

ROLLING RESISTANCE. See tractive resistance.

S

SLEEVE. See tube.

SPACER. See tube.

STILLAGE. Castors are regularly used in the production of stillages in order to aid the ease of movement of glass and other products.

SWIVEL CASTOR. A housing containing a wheel which is free to rotate about the vertical axis of a swivel head bearing with the castor wheel axle offset.

SWIVEL RADIUS. Usually the horizontal distance between the outside edge of the wheel and the vertical axis of the swivel head bearing. This may be increased by the fitment of a brake whose operating pedal can protrude beyond the outside edge of the wheel.

T

TRACTIVE RESISTANCE is the effort required to move a piece equipment fitted with castors or wheels. Usually expressed as a percentage of overall load.

TRAIL. See offset.

TUBE. The component of the axle set on which a plain or roller bearing wheel runs when fitted into a castor.

TWINWHEEL CASTOR. Two identical wheels mounted side by side in a swivel or fixed housing to increase the footprint and stability of the castor.

U

V

W

WASHABLE CASTORS contain precision bearings with labyrinth seals and are manufactured in corrosion resistant polyamide.

WHEELS revolve freely on an axle with the outside surface (in contact with the ground) constituted by the material of the wheel itself or by a tyre in any of a number of materials.

X

Y

Z