The type of construction of the wheel bearing is of great significance for the operating properties of a castor and therefore for the mobility of the equipment. Wheel bearings must meet the most varied requirements, such as load bearing capacity, duration of use, environmental influences, resistance to impact shock, resistance to rolling, and resistance to weather, etc. We distinguish between the following wheel bearings:
1. Plain bearing
A plain bearing consists of a bearing shell solidly connected with the wheel. It demonstrates positive characteristics. The wheel turns around the axle tube bolted to the housing. Wheels made of polyamides have gained general acceptance for castors. Plain bearings are used traditionally for transport equipment that will not be moved much. Under normal conditions plain bearings are maintenance-free and corrosion-resistant.
2. Roller bearing
The roller bearing consists of steel or stainless steel rollers that are positioned in a cage. These rollers roll between the axle tube and the wheel hub. Since in turning around the axle no sliding friction but rather rolling friction occurs, the resistance to rolling of the bearing is relatively low even at high loads. The roller bearing has become generally accepted as the standard solution particularly for transport equipment castors. Roller bearings are resistant, robust and, to some degree, maintenance-free.
3. Flange bearing
Flange bearings are compact, simple ball bearing units. They consist of a moulded sheet metal housing, in which balls roll between the inner and outer rings, and which has an elongated axle unit.
4. Precision ball bearing
The deep-groove ball bearing, also called precision ball bearing, consists of balls that run between a tempered inside and an outside ring. Even under extreme loads and at high speeds this bearing demonstrates very good operating properties. It meets the most stringent demands for load bearing capacity, resistance to environmental influences and easy running. Due to sealed bearings life-long lubrication can be guaranteed even under extreme environmental conditions. The single-row deepgroove ball bearing is the standard for the area of technically demanding equipment and heavy load castors.
