January 2020

38 n GEARS AND GEARBOXES January 2020 www.drivesncontrols.com Custom gearboxes extend lives of heavy-duty mine washers L og washers are used in the mining and quarrying of aggregates to remove the earth that clings to the small stones, and to sort them into predetermined sizes. They consist of long rectangular troughs, usually made from steel plate, with two thick steel shafts that run parallel along the length of the trough. Steel paddles, attached to the shafts, churn the aggregate as it is washed in jets of water to remove the earth and clay attached to it. As the aggregate is churned by the steel paddles, it also moves from one end of the trough to the other and sorted according to size. The steel shafts – or “logs” – are what give the washers their name. The gearboxes on the log washers are critical components because, if they fail, then production stops and a significant maintenance operation is needed to remove and repair them. A major manufacturer of mining equipment recently asked Renold Gears to design a heavy-duty gearbox that would be more robust and reliable than those used on similar log washers from other manufacturers. The aim was to reduce the cost of ownership for operators of these washers by cutting downtime and maintenance, and achieving longer service lives. Renold was able to design new gearboxes with the same footprint as the previous boxes, but with features that made them easier to install and remove for maintenance. Better quality seals and bearings, and a higher grade material for the gears and shafts is expected to result in service lives at least 30% longer than the previous gearboxes. Renold was able to offer the additional benefit of local support, including spares and service, for users around the world. n The new log washer gearboxes are expected to have service lives at least 30% longer than their predecessors The French naval vessel, LeMonge (right), has a very specific role – tracking rocket trajectories. To do this, she carries an array of radar dishes, including onewith a 14mdiameter that is the largest installed on any ship. The 225m-long vessel was launched in 1990 but last year the gearboxes that rotate the antennae got an upgrade. The replacement planetary boxes had to be precise, reliable and rigid, with a lowflank backlash. The navy asked Güdel to provide replacement boxes that wouldmeet strict criteria for speed, output torque, lubrication and operating temperatures. A prototypewas tested by the French Cetim laboratory – theTechnical Centre for Mechanical Industry – which found that it compliedwith the navy’s specifications without needing any modifications. Güdel then produced 11 of the size 350 gearboxes, which incorporate oil level and temperature sensors, and thesewere subsequently installed on LeMonge . The inset photo shows one of the newgearboxes. Photo: Guillamme Rueda