Useful Terminology

A selection of frequently used and useful phrases, particularly with terminology relating to castors and wheels.

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

Bolt hole: A hole in a mounting plate that allows a castor to be attached to the item to be moved.

Bolt hole pattern: The way that the bolt holes are configured.

Bracket: See assembly.

Caster: U.S. spelling of castor

Castor: A small wheel (usually used in sets), fitted into swivelling or non-swivelling (fixed) forks. The wheel is usually retained between the castor forks using a simple axle set. Can be attached to the bottom of a larger / heavier item to allow it to be moved easily.

Castor brake: A brake that is fitted to a castor which stops it turning when locked.

Ergonomic: Ergonomic means that something has been designed to be effective, efficient, safe and comfortable for a person to use in the workplace or elsewhere.

Fabricated steel castors: These usually consist of precision machined heavy steel forgings housing combinations of tapered roller or ball bearing races. The forks are 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 by fitting 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: A fixed castor consists of a wheel mounted between the forks of a non-swivelling housing.

Forks: The part of the castor into which a wheel may be fitted in conjunction with an axle set.

Headed spacer: The component of the axle set on which a ball bearing wheel runs when fitted into a castor.

Housing: See assembly.

Hydraulic: Hydraulic means that a device is moved by pressure from water or another liquid.

ISO: ISO is a rating which specifies requirements for a quality management system in an organisation. The organisation needs to meet a number of criteria in order to become accredited. BIL are ISO 9001:2015 and ISO 14001:2015 accredited.

King pin: The component of a swivel castor which usually secures together the separate swivel head and fork pressings.

Low level castors: Characterised by a high load in relation to overall height and typically are fitted with wide tread or twin wheels.

Modular: Modular means that something is made up of different parts. BIL’s AluTruk is a completely modular system that is fixed together using nuts and bolts. This means that different components (handle, frame, toe plate, wheels, accessories) can be chosen to create bespoke hand trucks.

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

Parking jack: A parking jack is normally used in conjunction with heavier duty fabricated castors and is not designed to lift any load but to act as a brake mechanism.

Pneumatic tyre: A pneumatic tyre is a tyre that is inflated with air.

Polypropylene: Polypropylene is a type of manufactured plastic.

Pressed steel castors: Castors that 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.

Puncture proof tyre: Puncture proof relates to solid tyres which are not filled with air and so will not puncture.

Retrofit: Retrofit means to add parts at a later date typically once a product has been built.

Rolling resistance: See tractive resistance.

Shore hardness: Shore hardness is a scale that measures how hard or soft a wheel is. Rubber will have a lower shore rating than polyurethane or nylon which are much harder.

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 swivel castor contains a wheel and an assembly unit (to attach it to the product you want to move). It is designed to rotate 360⁰ about the vertical axis of a swivel head bearing (with the castor wheel axle offset), thus moving in any direction. Ideal when equipment needs to be manoeuvred around corners or in tight spaces.

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.

Top plate: A metal plate that allows the castor to be bolted to the product.

Tractive resistance: The effort required to move a piece of 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.

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

Washable castors: Castors containing precision bearings with labyrinth seals and are manufactured in corrosion resistant polyamide.

Weld: Weld describes the joining together of metal parts by heating the surfaces and then pressing or hammering them together.

Wheels: These 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.