Mechanical torque limiters from Zero-Max, Plymouth, Minn., prevent overloads and jam-ups in automated filling systems, without cumbersome shear pins and complex arrays of electronic limit switches.
Zero-Max Torq Tenders use an adjustable, springloaded convexshaped pin and detent overload mechanism. An overload condition disengages the pin from the detent and stops power transfer. Once the fault clears, the device can be manually reset (without tools) to its prefault angular position, a plus for timed mechanisms.
The filling-systems maker Elmar Worldwide, Depew, N.Y., uses two models of Torq Tender torque limiters to safeguard mechanisms in its Monoblock bottle filler/capper machines. One limiter goes in a motorized height adjuster, the other in a timing screw that sends bottles through the system for filling.
A motor and rotating shaft drives the height-adjuster mechanism at about 100 rpm through an H-TLC torque limiter.
Mechanical stops limit travel of the filler head but alone can't halt upward travel of its adjusting column each cycle. Occasionally, upward force overpowers the mechanical stops, jarring them loose or knocking them completely off the machine. And, the column can bottom out and jam should an overtravel limit switch fail during downward motion. "The HTL-C solves both problems," says Elmar Project Engineer, Russell Wozniak. "To get the same level of protection before required multiple sensors and complicated wiring."
A face-mount Torque Tender disengages the timing-screw mechanism in the main gear drive to prevent damage when a downed or jammed bottle stops the screw from turning. The Torque Tender eliminates a shear pin, which must be replaced each time the screw jams, a time-consuming job. A full turn of the Torque Tender resets the pawl in the detent and reengages the drive shaft in its original position for a speedy restart.