The Hazards of Heavy Lifting

DBS Canada repairs mobile mining gearbox for iron ore application David Brown Santasalo’s range of shovel and dragline transmissions for the mobile mining industry are available as complete assemblies or as replacement components. A rope shovel is a bucket-equipped machine used for digging and loading earth or fragmented rock. Rope shovels are a type of rope/cable excavator, where the digging arm is controlled and powered by winches and steel ropes, rather than hydraulics. In mining applications, the rope shovel distributes materials such as iron ore into larger-than-life dump trucks. David Brown Santasalo (DBS) Canada delivers an extensive range of gear systems for shovels, draglines and other surface mining equipment. Last year, DBS Canada’s manufacturing facility in Montréal completed the repair of a mobile mining gearbox for a customer in the iron ore industry. This was a huge achievement for DBS Canada. The 27-ton gearbox required a complete refurbishment, consisting of new bronze bearings and roller bearings, renewed housing bores, new gears and pinions with DBS optimized geometry. Heavy Mobile Equipment “We’re always focused on critical gearboxes,” said Steven Bednarchuk, technical sales support, DBS Canada, “and we’re well known for making really good gear repairs, for instance, on stacker reclaimers in the iron ore industry.” Bucket wheel reclaimers are large machines used in material handling, particularly in mining and bulk material storage. There are various types, including bridge-type and boom-type bucket wheel reclaimers, which are suited for different applications such as coal, iron ore and other bulk materials. “These bucket wheel gear drives are very complex units, and our customers don’t want to risk anything or cut corners when it comes to the quality and viability of the equipment,” Bednarchuk said. “Since we have the capability to manufacture our own products and we’re very meticulous about the teardowns and analysis of our units, we have a very good nonreturn rate. The gearbox comes out of our facility almost brand new.”

The DBS Canada team gains a deeper understanding of these applications with each new project. “Our end goal is to ensure these repairs are done right the first time,” Bednarchuk said. “The equipment’s condition coming in for repair has proven that these markets have not been served very well for a long time. Many shortcuts were taking place—particularly in the gearboxes operating the boom on the rope shovels.” Like many heavy industrial applications, weight distribution during assembly and disassembly remains a critical challenge. The weight of the large gears and components are removed/added 1 by 1, thus shifting the center of gravity/weight around of the crowd unit, making it dangerous to work on because it wants to tip over. Meeting strict deadlines can also be a challenge in these industrial applications. “A short timeframe is requested, but it’s in the customers best interest to make sure the gearbox rebuild or refurbish is done correctly,” Bednarchuk said. “We’re honest about what needs to be done within the gearbox system and the timeframe it may take. All the gears in this application, for example, needed to be replaced.” Cracks that were detected within the enclosure by Non-Destructive Testing (NDT) were also restored. Once complete, DBS conducted a spin test performed with vibration analysis, to ensure the gearbox repair was delivered to the highest standards, ready to return to operating the electric rope shovel. “Ultimately my emphasis was on quality. Also, the fact we were going to spin test the unit gave the customer additional protection. These were steps our customer did not receive in the past. Typically, the unit was simply put together, sent to the site and installed,” Bednarchuk said. Without spin tests or vibration analysis, a mining customer could discover faults or anomalies after the installation resulting in weeks of additional downtime.