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Difficulties In Measuring Push/Pull: New Ergonomics Standards For Casters

We’re constantly trying to refine this measurement process, and in March of 2019, we presented our ergonomics project at the Applied Ergonomics Conference with Dr. Gary Allread of The Ohio State University Spine Research Institute. Much of the information from this presentation is laid out in this article, but below, we include a PDF version of our presentation.


Most people working with casters have had some sort of experience with push/pull measurement. However, whether or not you have realized it, there are tremendous inconsistencies from person to person and from facility to facility. Caster Connection has teamed up with The Ohio State University Spine Research Institute to establish a gold standard in push/pull measurement guidelines. Below are some reasons why we really need these standards in place in all facilities around the world.

But first, what can happen if you don’t have consistent measurements. First, an employee can get injured and can fatigue much faster. So, even if an employee doesn’t get injured, his or her productivity and general satisfaction with his or her job will be greatly affected. Second, it becomes very difficult to determine the relative effects of design changes (such as altered handle height, wheel diameter, wheel hardness, etc.) on the overall magnitude of the push/pull force recorded. So, in other words, you might not even know if the changes you made to your gear have actually improved ergonomics.

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In its essence, push/pull measurement is simply measuring the force that a practitioner is applying initially and through a given distance with different wheel orientations. In this way, we can adjust equipment, make improvements to operations, and gain a whole host of advantages. As simple as this seems, there are possibly over a dozen reasons how this can go terribly wrong.

The acceleration of the cart and, therefore the force that you are applying, can vary a great deal. In this way, we can gain a false reading before and after applying new casters. The angle of the gauge on the cart will also change the reading, and similarly, an initial jerk or lack thereof will skew results.

The distance that you cover when testing should be exactly the same from test to test, and at times, this is imprecise. At the same time, you need to cover the same distance in the same amount of time because you can inadvertently apply more or greater amounts of force with carts of the same build and casters. In order to really get an accurate measurement, you need to do many measurements to establish a benchmark rating. If a facility only does one or two measurements, all of the difficulties mentioned above may come into play.

Exact weights should also be used from test to test. This is somewhat obvious, but if this varies. The tests are useless. The measurement placement of the scale is also a hugely important part of the standard measurement procedure. If a person is not using the same point to place the scale, then the measurements will be dramatically different. Finally, different casters with different rigs will produce incredibly different measurements. Changing a rig is as important as the wheel in most cases. If tests are performed with different rigs, or rigs with different wheels, with no adjustment for these changes, the tests are virtually worthless.

All of these and other variables will dramatically affect how you and your company perform, stay healthy, and improve.

Stay tuned for the final results of our project with The Ohio State University Spine Research Institute to change the industry and lead the way with the gold standard in push/pull measurement and ergonomic improvements.


Be the ergonomics master of your company. With over 30 years of experience, we can help you get there. Let’s make an already good working environment great!