How the sandwich moves the bread

Since its creation less than a decade ago, the sandwich wheel has become part of the caster of the future. With the combined advantages of a hard wheel and soft wheel in the same product, the sandwich wheel has the characteristic of being two times less noisy than a hard tread wheel such as phenolic, polyamide or plastic. Furthermore, this wheel requires minimal starting effort in order to move a load, therefore reducing the risk of back injury.

The design inserts a super elastic rubber ring between the body and polyamide tread. By using a polyamide with a high resistance to impact, the wheel has the following advantages: low starting effort, ability to skid sideways, resistance to shocks, and high resistance to cleaning agents in the food industry. Its rubber ring helps to reduce rolling noise by eliminating vibrations so they are not transmitted to the rig and cart, and permits the equipment to roll over obstacles that would normally block a hard wheel.

One success story in the use of the sandwich caster comes from a Canadian bread manufacturer. Typically, bakers use four-wheel carts to deliver bread from their facilities to local grocery stores. In this example, which used 3-in. solid nylon casters, the facility switched to 4-in. sandwich casters. Afterwards, the manufacturer saw a significant decrease in the number of casters that needed to be replaced.

The solid nylon wheels originally used could not absorb the continuous shocks when, for example, the carts were accidentally dropped from the delivery trucks on to the pavement. Many wheels would break in half, resulting in increased maintenance time, repair costs and the unavailability of the equipment.

The company wanted to keep using hard wheels because of the ergonomic issues involved (the hardest wheels result in lowest starting effort), but it also needed the shock-absorbing capabilities of soft and elastic rubber wheels. The replacement sandwich casters provided shock absorption combined with minimal starting effort and noise reduction.

In another food processing application, food carts were loaded with 1,300 lb and manually pushed in and out of elevators at the plant, five to 10 times a day. The maintenance team found that the original hard phenolic casters were not withstanding the continuous shocks caused by the gaps between the elevators and the different floors. In addition to this, the stainless steel carts needed to be pressure-washed on a daily basis at high temperatures with food-grade chemicals.

Hard wheels were not an alternative because of the shocks involved and soft wheels would be a problem because of ergonomic issues, increasing the effort needed to move the carts. The solution was the use of 5-in. sandwich casters to allow the lowest starting effort, along with providing shock absorbance.

The reinforced nylon components of the wheel, in combination with its elastic rubber ring, contributed both to major replacement cost savings and to worker satisfaction.

Frederic Lagace is the sales director for Bleutec Wheels & Casters Inc., Brossard, QC, the North American division of Blickle, based in Germany. He can be reached at 1-800-463-2526 or flagace@bleutec.com.