This bulletin is generated as reference and notice for anyone that has any brand of patented track (also called hardened track) with a castellated (window) construction, or “skip welded” beams. These tracks have the appearance of windows, or sections of the web removed, or the bottom flange is not continuously welded to the web material.
Originally created as a measure to reduce the cost to manufacture and/or decrease the amount of steel used, these beams were predominantly designed for hand pushed operation cranes and trolleys. Later, many systems were applied with motorized drives for bridge and trolley applications in the work place. The majority of these systems are well over 45 years old. Engineered Lifting Systems, along with OEM patented track manufacturers, strongly suggest that plants using this style of track make plans to replace any patented track castellated or stitch welded beams with new full weld full web patented track rail. These beams have a history of failure without going to plastic deformation, instead just dropping the hoist/trolley and load. This happens for a number of reasons, but typically because of the general beam design. Web buckling will cause over stressing of the bottom flange, bottom flange welds failing, or cycle life of the high carbon bottom flange.
The green arrows in the above picture show where the bottom flange section was previously welded to a window beam section.
The red arrows show where an entire section of the bottom flange failed under load.
Another stitched welded patented track beam failure. If you have either castellated track or stitch welded patented track, we recommend that you inspect your track to start, and develop a plan for replacement of these tracks. For additional information please call Eric Brown at Engineered Lifting Systems 866-756-1200, or e-mail at email@example.com