Caster wheels come in a wide variety of materials, sizes and treads.   The type and size of wheels chosen depends on:

• the total weight of the load;
• the floor surface and its condition;
• any unusual environmental conditions, such as moisture, extreme heat or cold;
• exposure to chemicals, blood, fats, oil, salt, etc.;
• shock loading;
• noise limitations;
• speeds and duration.

Here are examples of 8 types of bearings used in the manufacturing on quality casters and wheels:

Manufacturers provide many accessories for specific applications:

• Thread Guards prevent thread and material from clogging between the hub of the wheel and the inside of the fork. They remain stationary while the wheel revolves.
  
  
• Grease Seals provide protection for swivel ball races and wheel bearings by keeping lubricant in and dirt out.
  
  
• Swivel Locks are devices to prevent the rotation of the housing rig.
  
  
• Wheel Brakes lock a caster and wheel by exerting hand or pressure on an operating level, forcing a brake shoe or band against the wheel hub or tread surface.
  
  
• Swivel Lock/Wheel Brake eliminates the necessity of separate units for locking the swivel and the wheel.
  
  
• Floor Lock attaches to the undercarriage of a truck to lock it in position.
  
  
• Miscellaneous Accessories steering arms, rybar tubes, rubber bumper guards, shimmy dampeners and other items are available for specific applications. Consult your manufacturer.
  

The user is responsible for proper maintenance and operation of equipment. Some equipment is abused or subjected to unreasonable demands. Don't overload or drop loads on carts or trucks. High speeds on rough floors can create severe impact or shock loads that may cause wheel or equipment failure. Periodically examine equipment for:

• Frame and Fasteners
  Tighten loose bolts and nuts and look for broken welds or deck boards. Look for frame distortion due to overloads or impact loads. A distorted frame can cause premature wheel failure because of abnormal loads on one or two casters. If casters are stem type, bolted or riveted in place, make sure the legs of the equipment are not bent and mounting bolts are properly secured. Always use lock nuts or lock washers in mounting casters. Be sure casters with expanding adapters in tubular equipment are held firmly in place.
  
  
• Lubrication
  Wheel and swivel bearings last longer if lubricated regularly. Some lube applied to friction points on the wheel hub, washer and leg surfaces of straight roller bearing systems reduces drag and improves reliability. Normal conditions may warrant lubrication every six months, but once a month may be necessary in a corrosive application. Cart washings may necessitate lubrication after each wash.
  
  
• Wheels
  Check for visible points of tread wear. Flat spots may indicate foreign material, such as string, thread, etc., causing wheels to bind. Thread guards will delay build-up of such materials. Loose casters or frozen wheels are other causes of this problem. Replace wheel and/or caster to avoid erratic rolling. After inspecting and making corrections, be sure axle nut is properly tightened. Use lock washers or nuts on all axles. Tighten loose axle immediately to avoid becoming cocked in the caster housing/rig and locking up. Keep replacement wheels and bearings on hand to avoid costly downtime.
  
  
• Casters
  If swivel assembly is loose, it may need to be replaced. If caster has a king bolt nut, make sure it is securely fastened. If swivel assembly does not turn freely, check raceways for corrosion or dirt. If equipment has rigid casters at one end, make sure caster housing/rig is not bent.