Renold Gears has supplied one of the largest worm gear sets in the company’s history to a steel plate manufacturer. The giant screw-down worm gears have a centre distance of over 32 inches and a ratio of 36:1. The worm shaft is nearly two meters long and together with the wheel they weigh in at 4,850kg, the approximate weight of three average sized family cars.


The screw-down worm gears were designed and manufactured to drive two large rollers for rolling steel slabs to the required plate thickness on a quarto reversing mill. The steel slabs could initially be up to 300mm thick and are rolled to reduce thickness and produce steel plate to customers’ exact specifications. During the rolling process the worm gears auto adjust by sliding on a special spline incorporated in the worm-wheel hub.

The original manufacturer of the mill press was no longer in business and the steel company was finding it impossible to obtain spares. A breakdown would have halted production and so Renold Gears was approached because of its ability to manufacture worm gear sets of this size and specifications. Also, as only minimal technical drawings were available of the mill it was necessary to reverse engineer the old worm gears to accurately and precisely reproduce the original design specifications.