How Swivel Lead Impacts Caster Performance
Correct swivel lead is important for overall caster health.
When engineering a heavy duty industrial caster for an industrial application, consideration of the appropriate swivel lead is an important aspect to achieving the correct and desired performance. It is important to this discussion that one first understands the definition of swivel lead. The swivel lead of a caster is defined as the distance from the vertical centerline of the caster swivel section to the vertical centerline of the wheel. Swivel lead can also be referred to as swivel offset or swivel radius This article will discuss how lengthening the swivel lead of a caster will affect the performance in the application.
Ergonomics – Keeping the wheel size and material constant, increasing the swivel lead is one way to improve the ergonomics of a cart fitted with industrial casters. Lengthening the swivel lead makes the cart easier to turn by reducing the force required to begin motion. Having lower force requirements reduces the fatigue on humans for a manually operated cart. However, increasing the swivel lead on an industrial caster also leads to a larger turning radius and reduces the ability to make a true 90° turn. So if casters are used in both a manual and powered towing application, the correct swivel lead can have a significant impact on the application’s successful implementation.
Caster Load Rating – Increasing the swivel lead beyond the radius of the swivel section diameter reduces the load rating of the caster. This is because the moment (force multiplied by a distance) experienced by the swivel section is increasing. This needs to be taken into account when designing casters for the application. The casters may be easier to swivel but the total load rating can be reduced. There is always the pressure between the maximizing loads while maximizing the force required to swivel the caster.
Tracking – When carts equipped with casters are used in a power towing application, the length of the swivel lead becomes very important. The longer the swivel lead is, the better the caster will track (follow a consistent track without wandering) the movement of the tugger pulling the cart. The longer lead will also help reduce caster which is affected by the lead, the wheel mass, and wheel material. Caster flutter is an undesirable condition where the caster begins to shimmy and vibrate while being towed and reduces the ability of the cart to track the towing device. Fluttering of carts that are in a train can be a significant safety issue that leads to personal injury caused by caster failure or items falling off the cart.
These reasons make the design of the proper swivel lead for the industrial caster application very important. Changes of the swivel lead can have a desired impact (reduced ergonomic force to swivel the caster and reduction of tendency to flutter) and it can also have a negative impact (less carrying capacity or flutter when used in a powered application). Getting the proper lead prior to implementation of new cart configuration requires significant planning and design. Taking the time up front will minimize the risk of down time and worse yet, injuries to personnel.
At Caster Concepts, Inc. the engineering staff will work with you to help you find the product and configuration that best fits your needs and the demands of the application.