A. Swivel Threaded
B. Swivel Plate Single Bolt
C. Swivel Plate Bolts
D. Swivel Metal Stem
E. Swivel with Brake

A. Nylon
B. Cast Iron
C. Pneumatic
D. Solid Rubber
E. Polyurethane

Fixed Castors - an assembly housing a wheel which cannot swivel about its vertical axis.

Load Capacity - The recommended maximum weight to be carried by a single castor or wheel. To determine the required castor load capacity, add the weight of the load and the weight of the cart, then divide by three.

Roll or Swivel Resistance - Defines the force required to move or turn a piece of equipment. This resistance depends on load, wheel diameter, and tread, bearing type, castor offset and the floor type. Also, the various bearing sizes, ball cover and ball diameter determine the swivel resistance. Low rolling resistance = excellent running conditions.

Swivel Castors - an assembly in which a housing containing a wheel is free to swivel without restriction about the vertical axis of the swivel bearing with the castor wheel axle offset.

System brakes - the wheel and swivel plate are immobilized.

Threadguard - on the rim of the castor prevents particles of dirt from entering the bearing and impeding its running properties.

Top Plate or Stems - Elements for attaching a castor to a piece of equipment.

Wheel brakes - only the wheel itself is immobilized.

 
A - System Brakes - the wheel and swivel plate are immobilized.
B - Wheel Brakes - only the wheel itself is immobilized
C - Threadguard - prevents dirt particles from entering the bearing.

Use the following rule of thumb:

hard floor - soft wheel; soft floor - hard wheel

The maximum footprint of a castor should always be below the allowable area pressure of the respective floor type. This guarantees the floor will have a longer life and unnecessary replacement is avoided. Use wider wheels as the equipment weight increases. This allows for a greater disbursement of the footprint and the pressure on the floor area.

Soft and wide wheel materials reduce the maximum pressure on an area - however, they reduce maneuverability of the equipment due to increased roll and swivel resistance. Hard and small wheel materials, offer great swivel and roll resistance, however they tend to increase wear and tear on floors. For the heaviest loads, choose Polyurethane or Steel wheels.

Resilient or Soft Tread Wheels: rubber, polyurethane
Hard Wheels: cast iron (the basic standard), nylon

The larger the wheel size (and swivel radius), the greater the mobility. The type of bearing selected will also further improve mobility and reduce rolling resistance.

Wheels with precision ball bearings have a very low rolling resistance, i.e. running conditions are superb right up to the maximum load limit of the wheel. The wear and tear of the precision ball bearing is minor, even under continuous use and replacement is usually not required.

The cup and cone bearing has certain advantages over the plain bearing, including a smooth and uninterrupted use, especially in good conditions.

Roller bearings are robust and shock-resistant, and are usually used in castors intended for transport equipment. This wheel bearing has the advantage of a low construction height, a relatively low rolling resistance, and a high load capacity. Wheels with roller bearings should not be used in speeds above 4 km/h.

Plain bearings are not sensitive against shock; they are mostly maintenance free and are rust free, depending on the material used. These bearings are usually found in wheels that are used on equipment, which is moved only at low speeds and only for short distances. Recommended when rolling ease is less critical.

The maneuverability depends on the arrangement and combination of the types of castors:

4 swivel rollers	optimum maneuverability • can turn on the spot • good stability • may veer from a straight line • suitable for winding runs, and where side motion is frequently required • not recommended for ramps
2 fixed castors 2 swivel castors	satisfactory maneuverability • very good stability • good straight-line running
2 fixed castors 2 swivel castors	good maneuverability • particularly suitable for long transport devices • overturns easily if weight is unevenly distributed • not recommended for ramps
3 swivel castors	excellent maneuverability • suitable for barrel dollies and small portable machines

Note: when combining different types of castors, it is important to take note of identical heights, otherwise there is a possibility of overturning due to uneven distribution of load.