There are a lot of factors to consider when choosing a heavy duty caster, but one of the first things to determine is how much weight you are moving. Exceeding the rated weight capacity can create a dangerous situation. Either through a steel caster failure or an overexertion injury from trying to push too much weight.
Let’s use an example of a cart that weighs 3,000 lbs. The first thing to remember is to include a margin of error. This is because when moving the load, the weight won’t always be evenly distributed across all four casters. Adding in more weight allows more pressure to be put on one wheel and lessens the chance of failure.
You also want to keep in mind the factors that come into play in addition to the load weight. The weight of the cart, rack, or whatever is being used to move the load, is also riding on the casters. The weight of that device must be added to the load weight to determine the proper weight rating for the casters. Note that casters are rated at the weight capacity for each individual caster, not a set of casters.
Once the total load weight is determined, a safety factor should be added to the total. We recommend adding a 33% addition to the total weight of the load for safety.
So, for a 4-wheeled cart that weights 3,000 lbs., the safety factor would equal 3,990 lbs. Dividing this weight by 4 gives a caster with a rating of 1,000 lbs per caster, which is recommended.
There are a few reasons why you need to add a margin for error. These include:
Here’s another example: A rack with the load has a total weight of 5,000 lbs, adding the safety factor would equal 6,665 lbs total. If the rack has 6 casters, a caster with a rating of at least 1,110 lbs is recommended. If the exact recommended caster capacity isn’t available, it is advisable to round up.
Besides knowing how much weight your casters can handle, you should look for ways to move heavy material handling carts with less exertion. New polyurethane wheel tread formulations can help. They are some of the most ergonomic wheels available and provide less resistance than other wheels. A good example of this is the maintenance-free TWERGO® wheel. These wheels rotate independently of each other and can rotate in either direction and at any rate with a minimum of rolling resistance. Because less force is required to move heavy loads, the risk of injury decreases.