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.
Swivel lead of a caster (Swivel offset or Swivel radius) is the distance from the vertical centerline of the caster swivel section to the vertical centerline of the wheel
Ergonomics-
- Constant- wheels size and material
- Improved Ergonomics by increasing the swivel lead. Lengthening the swivel lead makes the cart easer to turn by reducing the force required to begin motion.
- Reduced Fatigue by having lower force requirements for a manually operated cart
- Increasing the swivel lead on an industrial caster also leads to a larger turning radius and reduces the ability to make a true 90 degree turn
- Successful Implementation- if casters are used in both manual and powered towing application; the correct swivel lead can have a significant impact on the application
Caster Load Rating-
- Reduced 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 X 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 load while maximizing the force required to swivel the caster
Tracking-
- Power Towing Applications- 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
- Reduced caster flutter- 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. The longer lead will also help reduce caster flutter, which is affected by the lead, the wheel mass, and wheel material
- Prevent Safety Issues- fluttering of carts that are in a train can be significant safety issue that leads to personal injury caused by caster failure or items falling off the cart.
Plan Ahead-
· Desired impact- Reduced ergonomic force to swivel the caster and reduction of tendency to flutter
· Negative impact- less carrying capacity or flutter when used in powered application
· Get 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 personnel injuries