FAQ’s – Frequently Asked Questions

The questions below are representatives of the queries we receive from our customers. If you need further information about any of these topics or you have a question that doesn’t appear below, please contact customercentral@casterconcepts.com or call 800-704-1562.

Frequently Asked Questions


Q: What is Vari-Flex?

A: Vari-Flex is Modern Suspension’s unique shock absorbing, spring loaded caster design. Vari-Flex  design is extremely precise and optimizes deflection to utilize an average of 50% of casters deflection range at rated capacity. Vari-Flex achieves optimal shock reduction and drastically reduces shimmy, dynamic bounce and resonance, even when the cart is empty or loaded beyond its maximum rated capacity.

Q: Can spring loaded casters actually cause more shock and vibration?

A: Yes absolutely, if the wrong spring is chosen for the application, the spring could actually do more harm than good. If the spring constant is too high, it could essentially be the same as not having a spring at all. If the spring constant is too low, it could extend the impact of the shock and continue to vibrate excessively. The right spring is critical to achieving optimal shock and vibration reduction and especially elimination.

Q: What are the benefits of Aluminum?

  • High resistance to corrosion
  • Light weight, significantly lighter than other metals including Cast Iron and Steel
  • Looks good, aesthetically appealing and ideal for applications where appearance matters
  • Resistant to Water and many chemicals, ideal for higher humidity and other challenging environments
  • Dissipates Heat
  • Non Sparking
  • Non Magnetic

Q: Is aluminum sturdy enough for Industrial use?

A: Absolutely, while aluminum is not as hard a metal as steel or cast iron, it is strong enough to carry 6,500lbs per caster.

Q: What wheel options are offered with Modern Suspension Casters?

A: Modern casters are available with three types of wheels (listed below) as a standard offering, however custom polyurethane tread formulations are also available, contact our sales team for details. (Thermoplastic wheels are available on the 25 Series casters).

  • Polyurethane 95A Durometer Tread Material on Aluminum core
  • Mold On Rubber
  • Phenolic

Q: Why are they called Suspension Casters?

A: Modern’s dual wheel casters have an INDEPENDENT SUSPENSION, Each wheel is on its own separate axle with separate forks (legs), its like having two separate casters on one top plate. This is extremely beneficial because it helps to keep both wheels on the ground and the cart or dolly level, even when the ground is not, or an obstruction is encountered. It also helps avoid excessive stress on just one wheel, reducing the risk of failure and potential injuries.

Q: What should I be aware of when using casters outdoors?

A: There are several factors that may impact a casters performance when used outdoors, these include:

Environment / Weather : Excessive Humidity, Rain, Snow and other moisture can harm casters greatly, including bearings. Moisture causes rust and corrosion on the wheels and rigs, and can impact the performance of bearings.

Surface Conditions:  Cement, asphalt, and other surfaces commonly found outdoors are often uneven and may have cracks. They often have debris such as pebbles, garbage or other foreign elements that can stop a wheel from rolling and cause shock on the cart upon impact. Water puddles or high temperature surfaces are detrimental to polyurethane and other tread materials. Therefore it is important to understand your surface conditions and discuss them with your sales representative.

Speed: Casters are usually designed for optimal performance at walking speed, which is an average of 3.1 miles per hour. Faster speeds and the amount of time spent moving at that speed has a great impact on casters, and will cause failure.

We have the right bearings, rigs, wheels and other components to provide you with the right caster for your outdoor applications, please consult one of our sales people for the best configuration for your challenge.

Modern Suspension Systems is now part of Caster Concepts, for further information please call us at 800-704-1562 or