Considerations When Upgrading a Patented Track System
Welcome to the Hoist Guy's blog! In this post, we will investigate the trade-offs of upgrading the capacity on an existing patented track system.
by Andrew T. Litecky on June 15, 2016
“Can we add extra supports to make our 12-Ton patented track system safe for 16 tons?” This question was posed by an experienced engineer for our international manufacturing customer who was facing a challenge to rework the crane system for heavier loads. He was trying to avoid the purchase of an entirely new patented track crane system. However, a full investigation into upgrading the existing system revealed many trade-offs.
The original system included a 12-Ton underhung bridge crane with two interlocked monorail spurs, all made from patented track. The engineer based his calculations on the additional load and came to the conclusion that adding extra support steel to the runways and spurs could increase the load capacity of the system. However, to correctly calculate this increase, it’s important to consider the factor of wheel load.
Patented track is limited by the equivalent center load and by the maximum per pair wheel load. In this case, Tarca Track made by Cleveland Tramrail has a limit of 10,500 lbs per pair of wheels. If you increase the load from 12 tons to 16 tons, that’s a 33% increase, and it would put the per pair wheel load over the 10,500 lb limit.
To resolve this situation and reuse the existing equipment, we recommended an increase in the number of trolley wheels along with the added steel support. By changing the trolley wheels from 8 to 16, this would prevent the overload conditions on the lower flange of the patented track. However, as the old engineering adage goes, “you never change just one thing”, and in this case adding trolley wheels also meant adding headroom and losing space at the end approaches (since the new trolley wheels take up more room). Unfortunately, a major trade-off of this plan is reduced hook coverage across the entire system.
With this analysis, our customer was able to consider the full costs and benefits of a new system versus an upgrade. It’s important to note that only adding support steel without increasing the number of trolley wheels for this capacity increase, would have resulted in an overloaded system, potentially causing damage or a catastrophic failure.
Shupper-Brickle Equipment offers patented track bridge cranes, monorails, and engineering support. Contact us for more information on our services.