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We all know that the squeaky wheel gets the grease, but why wait to hear the squeak, or feel the drag of the wheel, or attempt to suppress vibrating casters?

The safe maintenance of casters should be part of a regular equipment maintenance program in any work place. Equipment safety in laboratory environments is critically important. In fact, workplace safety is everyone’s responsibility.

Casters in laboratory environments are much more common today. Casters are used to comply with occupational and workplace ergonomic policies that help to minimize sprains and strains. The safe operation of casters and wheels is very important to central supply professionals overseeing animal cages, research tables, and related monitoring equipment.

Safe Operation of Equipment with Casters
To keep casters rolling smoothly, casters should be inspected for frame tightness, lubrication, tread wear, free movement of the swivel assembly, and for corrosion or dirt built up especially in frequent wash-down application areas. Periodically turn equipment on its end or side and check the following:

  • Note any broken welds, corrosion, or other deformations.
  • Tighten loose nuts and bolts that hold the caster to the equipment or wheel attached to the caster housing.
  • Look for equipment frame distortion caused by overloads and impact loads. Distorted frames can lead to wheel failure by placing disproportionate loads on one or two casters.
  • If casters are stem types, make sure that the legs of the equipment are not bent and that mounting bolts are securely fastened.
  • Always use locknuts or lock washers to mount casters to equipment.
  • Make certain casters with expanding adapter stems are held firmly in place in tubular equipment.
  • Look for fallen or destroyed grease zerk nipples, swivel head seals, broken or missing thread guards, and replace.
  • Wheels under load over an extended period of time may develop flat spots. This is a very disruptive experience on laboratory animals. The entire cage will shake and vibrate as it is rolled along, even for short distances, with a flat-spot wheel.

Central supply technicians should keep maintenance records on equipment casters and wheels. This helps to facilitate a better evaluation of a problematic caster application, or to establish new criteria for the re-specification of casters on specific laboratory equipment.

Caster and Wheel Maintenance and Inspection
Caster and wheel lubrication is essential. The lubrication schedule depends on your specific application. Normal conditions may warrant lubrication every six months. However, for wet or frequent wash down application areas monthly lubrication is required.

Check the caster swivel assembly for excessive play due to wear. If the swivel does not turn freely, check for corrosion or dirt binding the raceways. When purchasing casters, it is advisable to get casters with swivel head seals pre-installed in both upper and lower raceways. Swivel head seals keep grease in, and dirt out of the important swivel raceways. If the equipment has rigid casters at one end, make sure that the caster fork legs are not bent, distorted, or misaligned due to side-thrust forces or impacts during use.

Check wheels for visible tread wear. Flat spots may indicate accumulation of floor debris, such as string, hair, or thread which can cause the wheel to bind. It may also be due to loads applied to wheels with little or no motion over time. Remove the wheel axle bolt and nut. Clean out foreign material and check wheel bearings for wear or failure. Re-assemble if parts are not damaged. Wheel thread guards may be installed to reduce buildup if string or hair is a continuing problem. After wheels have been inspected and repaired or replaced, be sure the axle nut is properly tightened. Use lock washers or lock nuts on all axles.

Brake Safety and Inspection
Check brakes for proper operation. It is recommended that caster brakes on animal cages be tested daily, or before each use of the equipment. Apply brakes one at a time and attempt to move the equipment to make sure that each brake is not slipping or loose. If brakes slip due to worn or damaged wheels, replace the wheels immediately and retest the brakes. If the brake mechanism itself is not operating properly, repair or replace it. Before returning the equipment to use, always retest brakes. Remember, total lock brakes ensure that both wheel and swivel are firmly locked simultaneously. During inspection, make sure the swivel head is firmly locked in place and that the wheel does not turn at all.

Strategic Role of Central Supply
With extensive mobile equipment in laboratory environments, workplace safety is an important assignment for central supply professionals. To keep equipment rolling, caster safety and maintenance is more than just another variable in the facility’s spend analysis. It is strategically important for the safe operation of very expensive and high tech laboratory equipment.

Mike Titizian is President, Colson Casters Limited, Cambridge, Ontario, Canada. titizian@colson.ca; www.colson.ca

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