Replacing one of a pair of planetary gearboxes for a mine in South Africa’s Mpumalanga province recently gave SEW-EURODRIVE South Africa the opportunity to pioneer a global innovation. It adopted an electronic solution to match the speed of an existing gearbox in a high-torque application and provided significant savings for the customer. This solution attracted the interest of the global SEW-EURODRIVE group.
When a mining operation found that one of its planetary gearboxes on a high-torque conveyor was failing, it called SEW-EURODRIVE – and SEW-EURODRIVE used its latest intelligent technology to provide a replacement that will deliver reliable performance.
Greg Lewis, Business Development Manager Projects for SEW-EURODRIVE, says the application at the mine required a customised and carefully considered approach.
“The application was in the plant where a steel-belt transfer conveyor moves extremely slowly – with the 4-metre-diameter head pulley turning just one revolution every 25 minutes,” Lewis explains. “Two planetary gearboxes drive the pulley, with one on each side. The mine was facing the impending failure of one of the gearboxes, and that needed to be replaced.”
With the original installer of the gearbox unavailable, the mine approached SEW-EURODRIVE directly. The company already has a good relationship with the mine and has provided most of the power transmission equipment on the site.
“One of the main challenges was that only one of the two gearboxes that drive the conveyor needed to be replaced at that stage,” Lewis says. “In this application, it is important to understand that the two gearboxes must run together, at exactly the same speed and torque. There can be no allowance for any variation in the speeds.”
SEW-EURODRIVE was able to match one of its units very closely with the unit being replaced, but there was still a very slight difference in the ratios. This led to a 0,001 difference in the revolutions per minute.
“Although this may sound insignificant, it makes a difference when the gearbox torque is a couple of hundred thousand Nms,” he says. “At this high torque level, any misalignment or desynchronisation can affect the foundation and potentially cause catastrophic failure.”
Input from one of SEW-EURODRIVE’s in-house engineers sees the use of MOVI-C technology in a way never done before.
With the expert input of one of SEW-EURODRIVE’s in-house mechatronics engineers, a solution was developed using the company’s MOVI-C technology in a way that has never been done before. The new planetary gearbox supplied by will match the torque of the original gearbox – ensuring that they turn at precisely the same speed. This solution involves removing the existing base plate and providing a new, drop-in solution with an SEW-EURODRIVE planetary gearbox – designed to match the current infrastructure in the plant.
“The technology on the new planetary gearbox constantly changes the torque to match the existing equipment,” Lewis says. To prove this intelligent design, SEW-EURODRIVE built a small-scale working mock-up for the customer to witness. Together with its own customised base plate, the ‘model’ arrangement was taken to site and demonstrated to the customer’s satisfaction.
It proved so successful that colleagues around the world in the SEW-EURODRIVE group asked to see it, so they could learn from the achievement.
Lewis adds that the project was designed and delivered by SEW-EURODRIVE as a complete solution – from the fully customisable panels to the electronics and the installation of the gearbox. The installed unit is an XP planetary gearbox with shrink disk, with a primary X-series gearbox as a further reduction unit to achieve the required ratio.
“We engineered the steel base to fit onto the existing concrete foundation without any modifications required from the customer’s side,” he says. The significance of the project is enhanced by the scale of its elements. At about 1,7 m in height – and measuring 2.1 m wide and long – the gearbox weighs about 6 tonnes. Moving at 0.07 rpm, it moves the steel belt that carries a fine cake of raw chrome material.
“There are not many companies that can produce a solution to meet such slow revolutions,” Lewis says. “At SEW-EURODRIVE, we are proud to be among those that can. This project has been especially rewarding too in that it demonstrates our capability in matching another footprint, eliminating the need for the customer to break down existing structures and build new ones.”
The particular requirements of the project called for extensive on-site engagement with the customer and detailed measurement of plant requirements. SEW-EURODRIVE’s engineers in Johannesburg produced the working drawings and from these, their global counterparts in the group could begin manufacturing the unit in Germany.
Lewis highlights the assurance that SEW-EURODRIVE can give the mine in terms of support, as the company has a long-established presence in the mining sector and the country. The customer was very happy with the creative solution and may consider similar replacements at other plants in the coming years.
“We are already assisting with our full-service technicians, and we can provide experts in electronics, mechanical engineering and mechatronics, as the need arises,” Lewis says. “The electronics in this solution will allow the mine to implement a range of enhancements in future, including safety features and monitoring of operations.”
For more information visit: www.sew-eurodrive.co.za