Heavy pair of wormwheel gearboxes made

A UK company has manufacturued the heaviest pair of wormwheel gearboxes in its history - each weighs 25 tonnes - for a steel mill in Asia.

Believed to be the heaviest pair of wormwheel gearboxes yest manufactured by Renold Gears, the combined weight of each gear box approaches 25 toones.

Renold Gears' Milnrow plant, near Rochdale, suppled them to an Asian steel mill.
The gear units form the main drives of a mill stand screw down mechanism.
The stand reduces recently cast steel billets into thinner width sections.
Large 220kW motors power the screw down units.
Each single reduction worm gear has a reduction ratio of 21.5/1 and have huge tooth thickness to withstand iover 530,000Nm of static torque.
The worm drives are made in pairs and are identical externally, but internally the gears are cut with opposite angle gearing known as left and right hand threads.
This gives the desired effect of giving opposite direction of rotation of the output when both units' inputs are driven in the same direction.
Renold Gears have manufactured and supplied many similar screw down gear drives in the past and also supplied the specialised worm gears to customers who have built them into their own gearboxes.
Stephen Whitehead, sales director of precision gears commented: "Where sudden and huge shock loads are going to be encountered, only wormwheel sets manufactured with the maximum tooth width are suitable.
Only the combination of hardened steel wormshafts and 'soft' phosphor bronze wormwheels allow these loads to be withstood with no detrimental effect on service life".
Robert Townsend Renold Gears' managing director, concluded: "Our capability to undertake complete custom made systems designed to meet the customer specifications, has enabled Renold Gears to continue to win these type of contracts in diverse markets around the world.
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