File cabinet casters are a type of furniture fixture that includes a fastener, housing and wheel and is placed on the bottom of filing cabinets so the entire unit can be moved as needed. In some cases, file cabinet casters are mounted directly on the bottom of the cabinet with screws or rivets, while other times the casters are optional pieces that can be inserted into pre-drilled holes in the base. Alternately, some file cabinet casters are not mounted to the unit at all and instead are attached to a flat frame on which the cabinet can be placed so it can be moved. Depending on many factors, the casters can be made from plastic, metal, rubber or a combination of materials and can be one solid piece or can have a separate tire on the wheel. Most file cabinets have four casters on the base — one in each corner — although there can be many more to support the weight of the unit for larger cabinets such as lateral file cabinets.
Almost all file cabinet casters consist of three pieces. The first is the wheel, which is the round part that rotates against the floor as the cabinet is moved. The wheel usually is a single solid piece, but it can be made from an inner rim that has an outer tire around it, although the tire usually is solid rubber and rarely has an inner tube or air inside.
The wheel is inside a simple housing on most file cabinet casters. The housing can be a fork, with each prong attaching to a section of the wheel, or it can be a single column that sits between two wheels that combine to make a single caster. In some cases, the housing has a decorative or protective cover that partially hides the upper half of the wheel. The main purpose of the housing is to allow the wheel to turn while providing a stable surface to attach to the bottom of the cabinet.
The last component of file cabinet casters is the fastening attachment that usually is connected to the housing. This can be a simple metal rod that plugs into the bottom of the cabinet, or it can be a flat plate that is attached to the cabinet to provide more overall support. For casters that plug into a cabinet, there usually is some type of plastic sleeve that fits into the holes to help protect the cabinet and allow the casters to spin more easily.
Some types of file cabinet casters have mechanisms that allow them to be locked so the cabinet does not accidentally move once in place. Other types have a second locking device so the wheels can be held in a certain direction, preventing the cabinet from sliding from side to side. Some file cabinet casters include well-calibrated ball bearings inside that allow the cabinet to be easily moved despite the actual weight of the cabinet.