MechChem Africa July 2019

Harsh operating conditions on vibrating screens demand high quality engineering and the strictest tolerances for unbalanced motors and gearboxes, or they simply will not last. This is why Kwatani designs its own range of motors and locally manufactures gearboxes for its vibrating screens with a zero-tolerance approach to quality. Using quality motors and gearboxes optimises screen economy

A ccording to Kenny Mayhew- Ridgers, chief operating officer at Kwatani, local design and manu- facture to the highest standard is non-negotiable for Kwatani and its products. The company designs its own range ofmotors and locallymanufactures thegearboxes for its vibrating screens. “We design our own motors with local

conditions inmind, giving the customer a high performance and long-lasting product,” says Mayhew-Ridgers, adding that optimal sealing arrangementsmust beconsidered for keeping electrical components dry and clean. “Power cables, for instance, must always enter from the underside to prevent water ingress,” he says. “Thedesignmust consider various orien- tations of the motor, depending on the angle of installation.” Dusty conditions on

Unbalanced motors engineered to internal technical specifications and manufactured exclusively for the company in partnership with one of the world’s leading motor manufacturers in Europe. ment for the lid, which includes a gasket.” Kwatani’s gearboxes are locallymanufac- tured, with only the high-quality bearings im- ported direct from leading global producers. Gearboxes comprise two shafts, eachwith its own set of unbalancedweights linked to each other by a gear to achieve synchronised mo- tion. Gears and shafts are locally fabricated by selected suppliers, while the housing is cast by a local foundry and machined to

mines also present a challenge. “Dust ingress can compromise the sealing configuration of the lid. Our design is therefore like a top-hat, so theO-ring is not on a flat surface but rather on a cylindrical, vertical surface. There is even a double-sealingarrange-

Exciter gearboxes are engineered and manufactured in-house to the most stringent quality standards.

The cost effective variable speed drive option Grant Robertson, managing director of Vert Energy, talks about the company’s Leroy-Somer LSK direct current (dc) motors, a cost-effective solution for variable speed applications.

“ L eroy-Somer has a depth of experi- encewith ac anddc variable speed drive systems and designs its standardmotors to withstand the new demands being imposed by frequency converters and variable speed operation,” says Grant Robertson, managing director of Vert Energy, the exclusive distributor for Leroy-Somer in Southern Africa. “Motors are thus able to withstand frequent speed or torque changes and reversals, running at overspeed of up to 6 000 rpm for the stan- dard four polemachine, and at lower speeds with full torque, without drawbacks such as overheating,looseningofstatorwindingsand damage to rotors or bearings. “The major advantage of direct current motors is the ease of effecting accurate speed control and LSK’s advanced technol- ogy enables motors to respond to electronic controllerswhichplacegreatdemandsonthe performance of DCmotors. Smooth running

has been achieved by the introduction of an advanced frame design, incorporating the largest dimensioned shaft.” LSK square laminated frame dc motors, which have been designed by Leroy-Somer to the latest European standards for indus- trial requirements, have ratings from 2.0 to 750 kW. Leroy-Somer also produces non- standardmotors, providing a range of power from 0.06 kW to 18.5 kW. Vert Energy’s LSK dc range includes en- closed permanent magnet motors, enclosed wound motors, drip-proof wound motors and drip-proof, force-cooled wound mo- tors. These can be foot, flange or foot and flange mounted. Flanges are incorporated into the steel stator castings, giving a robust construction that eliminates vibrations. Four removable plates allowdirect access to brushes for easy replacement, thus simplify- ing maintenance. Leroy Somer’s advanced design of the

dc motor incorporates cooling and ventila- tion systems that reduce wear and tear on the brush gear, by the elimination of dirty particles. These motors, with a Class H insulation system, can operate at ambient tempera- tures of between +5.0 °C and +40 °C and are protectedwitha rangeof surface treatments that withstand harsh environments. The qualityof thewinding, insulationand impreg- nation guarantees optimum performance, even in arduous conditions. Optional features includeflange adapters that enable the easy modification of motors to all types of situations, without the need

12 ¦ MechChem Africa • July 2019