Wheels, or casters as they are called in industrial settings, are found in almost every industry from the neighborhood bakery and laundry, to hospitals and manufacturing facilities. Mobility is provided by casters. Defined as wheels on swivels, casters can be attached to the underside of almost any object to give it the ability to roll and rotate 360 degrees.
Because not all objects roll equally well on all surfaces, it’s important to select the most appropriate type of caster for the intended use, as well as to ensure that they are well maintained.
Most carts and other rolling devices can be modified to work more efficiently by replacing the original caster to one more suitable to the particular industry or physical condition in which it will be used. Some aspects to consider:
Maximum weight the device will be moving. Heavier loads benefit from using larger diameter wheels, which are able to evenly distribute the weight, and require less force to move.
Weight capacity of the caster. Casters are weight-rated, so it is important to choose casters that are capable of handling the maximum potential load the device may carry. To calculate this, divide the total weight (including the weight of the device itself) by one less than the number of casters being used. This will provide the expected weight capacity of each caster. For example, if the total load, including the device, is 600 lbs and four casters are being used, divide 600 by three. In this case, 200 pounds is the expected weight capacity for each caster.
Operating environment and wheel material. Factors such as hot, cold, wet, dirt, and density should be considered as this affects caster performance. When acids, oils, or corrosive chemicals are present, wheels made of polyurethane are required. Carpeted surfaces require a hard tread wheel, while surfaces like hardwood and linoleum require a softer tread wheel. This applies to chairs as well. Pneumatic wheels are good for many situations, but require more maintenance and are less appropriate for carts that carry heavy weights and remain sitting while loaded for several hours at a time, as the static weight tends to flatten out the tires.
Companies that use carts and other wheeled devices, should develop a wheel maintenance schedule that includes regular inspections (at least semi-annually) and documentation. Scheduled maintenance should include:
- Tightening any loose nuts and bolts. Look for broken welds or deck boards, and check for frame distortion.
- Lubricate wheel and swivel bearings every six months under normal use. In corrosive conditions, lubricate the bearings once a month. If carts are washed, (common at hospitals), lubricate after each washing.
- Casters should be free of debris that may get twisted around the axle such as lint, string, and hair.
- Flat spots in tread may indicate foreign material, a loose caster, or a frozen wheel. Address this immediately.
- Check caster swivel assemblies. If they’re loose they may need replacing; if they do not turn freely, check bearing raceways for corrosion or dirt.