Carts and Casters: Performance, Safety and Ergonomics
Contributed by: The Institute of Caster and Wheel Manufacturers (ICWM)
A cart began as a two-wheeled vehicle, pulled by horses. Now, in every industry, as far as the eye can see, there are carts of all different types, for many different purposes.
From shopping carts at your favorite store, to carts carrying lifesaving equipment at a hospital, aerospace and automotive material handling carts, to the many types of carts used in the agriculture industry, and everywhere in between.
Casters consist of a “rig” (the housing for the wheel – typically a swivel or rigid rig), a wheel, a bearing in the wheel and at times accessories such as swivel locks, and a variety of types of brakes. There is no limit to the number of combinations of rigs, wheels and accessories available, which allows companies to complement and improve any type of cart.
Casters are the single most important part of a cart when it comes to performance, safety and ergonomics. The wheel and bearing selection are critical when designing a cart. Defining the use of a cart is also critical when selecting casters. Will it be hand operated, towed, carrying heavy loads, or going over obstacles? These are just some of the key things to consider. Other important considerations would be determining if the casters need to have a brake, so it doesn’t move when not in use, or will the environment (weather, temperature, washdowns) be impacting the casters during their operation.
Each industry has its own particular needs and requirement for its carts. One example is in the grocery and retail industries. Alvar Diaz, ICWM Marketing Chair and VP Sales & Marketing, P&H Casters states, “with retailers shifting towards buy online with store pick up, the need for carts to deliver goods to vehicles becomes more sophisticated. Carts are now utilizing Central Braking Systems so that one pedal locks all wheels versus individually locking each wheel. This gives users more control when unloading goods.”
When walking into any health facility it becomes immediately clear that few industries use as many carts and casters as the medical industry. From the ER to the hospital room, and all of the laundry, food, monitoring and bio medical devices between them, everything is mobile, thanks to carts and casters.
Natacha Smith of TENTE states, “Medical carts are required to meet many different customer requirements and norms, such as rough handling tests. Examples of rough handling tests are driving down a step, going over a large threshold, or running into an obstacle. Casters typically take a lot of the abuse when these tests are performed, and the casters must be functional at the completion of these tests. These tests have been created to simulate real-life conditions, such as moving the cart, often containing high-end medical equipment, in and out of an elevator. Typically, medical carts require low pedal force, strong wheel brake and low noise. Caster selection has a huge impact on all of these requirements.”
In manufacturing and assembly plants, the use of a cart has changed drastically in the last 20 years. Up until the late 90s, heavy carts were towed, requiring high-capacity softer wheels, and lighter carts were hand pushed, using harder wheels to aid in ease of start motion. Scott Fisher, from the Colson Group, states, “the growth of lean manufacturing now requires carts to handle loads of 2,000-3,000 pounds, not only to stand up to the rigors of constant towing, but also requiring casters that allow for ergonomic ease of use when uncoupled for hand push operations.”
Caster types and wheel materials have also changed over the last few decades, allowing for a greater ability to specify the best caster for any requirement. Typically, there are good, better and best options for caster requirements, depending on the budget and performance needed for each cart project. Polyurethane and thermoplastic rubber are the most widely used materials. Manufacturers have the ability to tweak these materials to better meet the project requirements. Adding dissipative compounds can give a polyurethane anti-static feature for carts in electrostatic environments, as an example. Increasing or decreasing the shore hardness of these materials can also easily be done to better meet the requirements.
Ergonomics has become a key touchpoint when discussing carts and casters. Casters are the single most important factor in ergonomic improvement for any cart. The first three easy steps in improving ergonomics, or “decreasing the start force required” for a cart, are:
- Increase the diameter of the wheel
- Increase the hardness of the wheel if possible
- Improve the bearing in the wheel.
Then, depending on the specification, there are different wheel materials that offer more resilience, aiding in ergonomics, different swivel sections that aid in decreasing the start force and even the shape of the wheel can make a cart easier to start in motion. A caster specialist can help develop the right caster for your cart, whether it’s a new cart program, or you’re looking to replace casters on a legacy cart to more cost effectively improve ergonomics, increase capacity or simply make the cart last longer. WMHS
The Institute of Caster and Wheel Manufacturers (ICWM), an industry group of MHI, members are the industry’s leading suppliers of casters, wheels and industrial trailer trucks, platform trucks and towline trucks. They supply caster and wheel solutions worldwide and in virtually every major manufacturing and distribution sector. The association was formed in 1933.
With a simple vision statement of “Connecting the right casters and wheels to the right application,” ICWM has organized everything from a Casters 101 PDF, to a helpful application library, to an interactive document featuring ANSI ICWM: 2018 Vocabulary, Performance and Testing Requirements for Casters and Wheels.
Access the ANSI Standard and casters and Casters 101 guide here: https://online.fliphtml5.com/bwarp/icqp/#p=1
To learn more about ICWM and access free and helpful industry resources, visit: www.mhi.org/icwm
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