A prominent scrap metal recycler in the United States required a new shaft turning and locking system for a sizable auto shredder situated at one of its central Florida facilities. The turning/locking device is needed when power to the shredder is shut off so crews can replace damaged hammers on the large mill rotor. During this maintenance operation, the rotor becomes significantly unbalanced as hammers get removed. This causes the rotor to rotate, creating a dangerous condition for workers.

A manually-operated winch that required time-consuming movement of the rotor drive during maintenance had been previously installed on the shredder. Working closely with the facility operator, Twiflex engineers designed a stationary drive solution that was significantly more cost-effective than the competitive design.

The new Twiflex custom Turning/Locking (TL) System was installed on the hammer drum drive shaft near the 3000 HP drive motor. It allows continuous bi-directional turning at slow speed so workers have easier access to damaged hammers. The remotely operated locking device securely holds the rotor in place preventing unwanted rotation.

The compact system includes a manually engaged and disengaged turning gear drive pinion with a 1.1 kW motor to produce 21.7 kNm start-up torque, acting on a 1500mm dia. x 30mm thick, radially-split gearwheel with a nominal turning speed of 0.3 rpm. The locking device is a pneumatically engaged/disengaged tooth lock (2 teeth) which automatically engages with the gearwheel to provide 47 kNm torque.

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