An international metals recycler was suffering from recurring damage to the motors and universal joints caused by torque overload when the shredder rotors jammed caused by an un-shreddable obstruction. During a jam the torque generated was so excessive that damage was being caused to the components within the drive train, such as the universal joint bearings and even the motor itself. In this instance not only could the repair bill becostly, but the downtime could be considerable while the obstruction was cleared and the drive train repaired or replaced. In total, up to 48 hours of downtime was required each time the rotors jammed.

In an effort to save on maintenance costs and reduce downtime, the site manager turned to Ameridrives, a division of Altra Couplings, to see if its engineers could design a solution. As a manufacturer of industrial couplings, Altra Couplings develops bespoke solutions for most industries which incorporate reliability with reduced operation costs.

Having assessed the application, Altra’s engineers designed an overload protection solution into the universal joints which would protect the components within the drive train in the event of a jam. An Americarden U3440 universal joint was modified to incorporate a shear pin overload device. When a rotor jam occurs, and torque reaches in excess of 533,000 Nm, the pins shear, disengaging the driven end of the universal joint from the driving end and protecting the components from damage.

The solution also meant that, after clearing the jam, a maintenance crew can replace the pins and have the shredder operational in less than four hours – reducing downtime by over 95%.