Swivel Casters
Swivel casters allow caster wheels to move in multiple directions, giving furniture on swivel casters greater ease of movement than furniture attached to rigid casters. It is important to consider aspects such as load carrying capacity, swivel caster and wheel dimensions, flooring materials and environmental conditions before selecting a swivel caster for any application. Being able to roll tables, chairs and equipment platforms around smoothly is important in the manufacturing industry, in workshops where equipment, workstations and chairs are frequently moved around the facility. It is also very important in the medical industry, such as hospitals, where computer stations, beds, IV racks and other equipment are constantly in transit.
A swivel caster consists of a caster frame and a wheel, constructed so that the caster frame houses the wheel. When the wheel is installed into the caster frame, two legs are attached to either side of the wheel and the wheel is held in place between these two legs by an axle or bolt. Positioned above the legs is a swivel bearing, a component that provides the swivel caster with a full 360ยบ range of movement. The swivel caster is commonly attached to equipment through a mounting plate, or top plate, that is connected to both the swivel bearing and to the two legs. Mounting plates generally contain four holes used to bolt the swivel caster to the equipment. Typical materials used for swivel casters include: metal and plastic coated metal, which has the greatest load capacity; rubber, which allows for silent movement; hybrid rubber, which provides both silent movement and a high load capacity; and thermoformed plastic, which offers a high load capacity.
In the past, all swivel castors used kingpins both to attach the caster housing to the caster bracket and to provide pivot motion. Kingpins absorb a significant amount of stress, particularly in high-impact industrial applications, and they are consequently the number one cause of swivel caster failure. "Kingpinless" casters have become quite common among medical casters, office casters and even industrial casters. In kingpinless casters, a raceway of ball bearings connects the upper bracket to the caster housing in place of a kingpin. These are not only far more wear-resistant, but provide smoother swivel motion as well.