STARTING EFFORT

You may recall from our last edition that I gave you the first part of a two-part article on ergonomics and starting efforts. As promised, here’s all you need to know about starting efforts.

What do I mean by starting effort? Basically, it defines the amount of force (push or pull) needed to start moving a load on casters.

Guitel has two methods to determine this force:

The first method is used for "on-site" verification. This is when a potential customer wants to precisely compare the starting efforts of rolling equipments at their location. A dynamometer is used to push a caster- equipped cart. This measuring equipment will precisely indicate the force required to get the cart to move and to keep it moving. Once the cart begins to move, they read the measurements given by the dynamometer in lbs. or kgs and other force measuring units, like Newtons.

The second way to determine these starting efforts is with a special device manufactured by Guitel (see picture). I would sound like a nerdy mathematician if I were to describe exactly how this device works. Why don't you call me if you want the details!! Basically, the measurements given by this device are very precise, and much easier and faster for Guitel to read. This "machine" is installed in Guitel's R&D department so that they can quickly compare results for different types of wheels and loads.

With this device, Guitel has come up with the following data for their products, as well as for other types of wheels available on the market.

TYPES OF WHEELS	STARTING EFFORTS IN % OF TOTAL LOAD
PHENOLIC	1%
BLUE RESILEXtm RUBBER	2.3%
GREEN RESILEXtm RUBBER	1.3%
BLACK RESILEXtm RUBBER	2.1%
NYLON (PA.) and most plastic wheels	1%
NORMEUROPtm RUBBER	4%
POLYURETHANE	3%
SANDWICHtm WHEEL	1.5%
HARD RUBBER
(what I call hockey pucks, plain bearing)	5% and more

The information in the above chart was measured with 5" diameter wheels with roller bearing hubs. To put this data into perspective and as an example: if you have a 500 lb. Cart on four 5" Blue Resilex casters with roller bearing hubs, the starting effort will be: 500 X 2.3% = 11.5 lb. This means that you will need to apply a force of 11.5 lb. to get this cart to start moving.

There are many more intricacies about starting efforts. With this article, I only wanted to give you an overview of the possibilities. I did not mention anything about maneuverability and what happens when the casters need to swivel right at the starting point. The data collected by Guitel only shows the efforts required when all the casters under the same cart are in the "pushing direction". The types of bearing, tread qualities and wheel sizes will effect the starting efforts dramatically.

You may want to see how your carts perform in terms of starting effort. Who knows, this could show that your employees are spending way too much energy to move loads in their working environment. You could then compare your data with ours and find out how much effort, time and money we could make you save. Here's a tip: if you want to quickly measure the efforts required to move your carts, you can use a standard fish scale. Let me know how it goes!

Frederic Lagace