One thing many of our customers struggle with is understanding the meaning of the weight limits mentioned in the specifications for certain casters. Many people see some of the larger dynamic load numbers and think that this must be the load applied to more than one caster, but this is not the case. The load you will apply to the casters will be distributed across all the casters under the weight, so you need to take this into consideration when choosing the casters you want to use for your material handling application. At Douglas Equipment we have been helping people like you to understand what casters are needed for their unique needs for over 60 years, and our dedicated team of experts is more than willing to answer all your questions to make sure you get the exact casters you need.
Why Not Just Publish the Capacity for Four Casters?
If you think about one of the most common pieces of equipment that includes caster, the office chair, you can quickly understand why the capacity loads are not just for four casters. Some office chairs have four casters, but others have five casters. This is due to the maximum load that the chair can hold with all casters, and the five caster chair can hold 25% more weight than the four caster chair. Here is how it works:
For the Shepherd Baron caster (highlighted below), the identified dynamic load per caster is 70 pounds to 80 pounds. Using 80 pounds, a four caster chair can hold a dynamic load of 320 pounds, but a five caster chair can hold a dynamic load of 400. The additional 80 pounds of load is 25% of the 320 pounds that the four caster chair can hold, so the five caster chair can hold 25% more load.
- Shepherd Baron Series: These casters from Shepherd have double ball bearing raceways for smooth motion, and are ideal for furniture, fixtures, medical equipment and office equipment. The 2″ Model is heat treated for better wear, has a hard synthetic spherical polyolefin wheel, and the finish options are bright chrome, metalized brass, and Windsor antique. The units can even be RoHS compliant upon request.
What does this mean when I’m choosing casters for my task?
From the example above, you can see that putting a load of 380 pounds on the two chairs will be over capacity for the casters of the four caster chair, but below capacity for the casters of the five caster chair. So when choosing casters for your task you need to know the maximum load that will be applied and how many casters you want to use to distribute the load. If you want to move a load of 6,000 pounds on a cart that will be fitted with four casters, you will need casters that can withstand a dynamic load of 1,500 pounds each. The larger of the Colson 6 Series Enforcer models with 5” or 6” forged steel wheels would meet the minimum requirement. With 8” wheels you have the option of mold-on polyurethane, mold-on nylon or phenolic wheels and you can also carry the same load. If you wanted to allow for some margin then choosing the larger Shepherd Bassick Honcho HS/HR Series will allow for a maximum capacity over 6,000 pounds.
- Colson 6 Enforcer Series: These Colson casters come with an attractive and durable zinc finish, as well as the kingpinless swivel design that eliminates swivel section failure due to shock and stretching of the kingpin. Wheel material options include Performa rubber, mold-on rubber, polyolefin, Polyurethane HI-TECH, cast iron, Mold-on Nylon, Phenolic and Thermo High Temperature, and come in wheel diameters of 4”, 5”, 6” and 8”. Caster capacities range from 300 pounds to 1500 pound to suit any needs you may have.
- Shepherd Bassick Honcho HS/HR Series: This is a heavy duty caster from Shepherd and is built to carry a large amount of weight while remaining strong and dependable. These casters are perfect for power-towed applications, terminal trucks, or other heavy, abusive applications. Wheels are 2-1/2” wide and come in material options including Urethane on Aluminum, come in wheel diameters of 6”, 8” and 10”, and have a capacity of 1750 pounds for moving larger loads.
Can I add more casters to my cart to increase capacity?
This may be one of the best ways to increase your maximum dynamic load capacity while using a smaller capacity caster that includes other beneficial properties but has a lower dynamic load rating. If you’re using a larger quantity of casters, you’ll need to make sure they’re installed in such a way that all of the wheels are in solid contact with the ground. This will keep the load evenly distributed between them and prevent overload damage to a single caster while preventing the load from tipping over. For example, if you wanted to move the same 6,000 pound load, but wanted a cart that had the Colson Evolution Maintenance Free Casters for Towed Applications so that you can take advantage of the maintenance free swivel raceway that it uses, you would need to add a fifth (or even sixth) caster to your cart for a larger maximum load of 7,000 pounds (or 8,400 pounds with six casters).
- Colson Evolution Maintenance Free Casters for Towed Applications: This specialty caster from Colson comes with a zinc plated finish and is designed for dynamic towing applications with a maintenance free precision swivel raceway and steel top plate for maximum durability. All wheel options are 8” diameter and 2” wide with material option including performa rubber, mold-on rubber, polyolefin, polyurethane HI-TECH, Endure Solid Elastomer and cast iron. Caster capacities range from 500 pounds to 1,400 pounds.
How can I find out more?
If you need answers to a few questions or need help choosing the casters that best meet your needs, contact us today!