Speed reducers are key

Heavy-duty power-dense speed reducers have proven themselves on challenging 1,200m long coal conveyor high above the floodland of Kentucky’s Green River.

Overland Conveying Systems, based in Madisonville, Kentucky, USA, designs and builds conveyor systems, primarily for the coal industry. One of its key customers is Armstrong Coal, a company that controls approximately 415 million tons of proven coal reserves in Western Kentucky, and a leading producer of steam coal in the Illinois Basin.

In late 2008, Overland Conveying Systems won the contract to create the conveyor system for Armstrong’s newest mine site, the Equality Boot mine, located about 13 km from the company’s prep plant. Trucking coal over county roads or conveying it overland were not options, so Armstrong needed to transport the coal by barge on Kentucky’s Green River. The project involved over 1000 metres of conveyors down to the river for load-out, plus a new system to offload the coal from the Armstrong dock up to the prep plant.

At the mine site, Overland Conveying Systems’ chief engineer, David Daniel, had the challenge of building a 1200-metre-long conveyor high enough off the ground to evade the annual river flood. The only way to reach key equipment during a flood is via a narrow catwalk 6 metres off the ground, which runs from the mine to barge load-out. Consequently, Daniel required a reliable gearbox that wouldn’t need a lot of attention, small enough to fit in a confined space, but powerful enough to handle the work.

Around the time Daniel started the project, Baldor introduced the full line of MagnaGear XTR high horsepower speed reducers; these are compact, power-dense designs in a heavy-duty package. Based on his experience with other Baldor•Dodge gearboxes, Daniel was eager to see the new gear reducer and obtain more information, “I’ve used the company's Torque-Arm reducer for years on many projects with a lot of success. This product sets the standard in our industry because they do the job, are user-friendly, and last an extremely long time. Consequently, we were keen to take a serious look at the new speed reducers, because we naturally expected them to be just as good.”

Convinced that the MagnaGear was the right product, Daniel worked out all the designs and product specifications to present to Armstrong Coal for final approval. His plan included a total of 10 Baldor•Dodge MagnaGear reducers, coupled to Baldor•Reliance Mining Industry motors. Despite the newness of the product, Daniel says Armstrong sanctioned the plan thanks to the reputation of Baldor•Dodge gearing.

“Like me, they knew that the gearing is well respected in the marketplace,” says Daniel. “Baldor•Dodge is not new to this industry, and has been cutting gears for a long time. We didn’t hesitate because we trusted that this gearbox would be a good product and that we would get good support from the company.”

Some of that support came from Baldor’s System-1 group, a team that facilitates the design, quotation and order processing of multiple power transmission and electrical products into a complete packaged solution. While Daniel performed all his own calculations and chose the motors and reducers, he appreciated the System-1 team confirming his selections, plus the help they provided on other products required for the job.

“I don’t have the same level of knowledge on couplings, sheaves and guards,” says Daniel. “I simply let the System-1 team handle all of those details, and when the equipment arrives at our facilities in a complete package, my facilities manager doesn’t have to worry about it either.”

Daniel says the reducers have delivered everything he expected from a Baldor•Dodge brand gearbox, from installation to performance. And he points to several design elements that he believes make this reducer an ideal choice for high torque applications, including its power-dense design.

“The way engineers designed this product means we get more torque out of a smaller reducer,” explains Daniel. “This makes the MagnaGear very appealing because you get more torque for the money compared to others in the market. It’s a very cost-effective package.” Daniel says the compact design of the reducer has also been a plus on the Armstrong project, because many of the units are located along a catwalk or in other confined spaces.

“Not only are the units compact, I also like the way the reducer is coupled to the motor,” says Daniel. “The coupling housing is only 50 cm long; others in the marketplace are up to a metre in length, which causes a lot of problems. The engineers who designed the MagnaGear obviously understand the industry because they built us a product that we needed.”

The versatility of the reducer is also appreciated by Daniel. MagnaGear reducers are available in parallel shaft or right-angle configurations with solid or hollow output shafts. They also come in several mounting configurations, including tunnel housings. For Daniel, the reducer’s universal housing design also means the customer doesn’t need to keep multiple spares on-site.

“The reducer is set up to work on either side, so I have the option of right-hand or left-hand mounting,” explains Daniel. “Now, I only need one spare that can work anywhere on the project. Other products on the market do not offer this level of flexibility.”

The first coal from the Equality Boot mine was loaded and unloaded in September 2010. Since then Daniel says the reducers have done the job everyone expected them to do, moving coal with no issues. Both Overland Conveying Systems and Armstrong Coal are so pleased with the performance of the product that Daniel has purchased seven MagnaGears on a new Armstrong Coal project.

“All I can say is that if the MagnaGear product didn’t work, or if we had any problems, I would not be using them again,” says Daniel. “But it’s a good product, and I had a good experience working with Baldor on the Boot project, and that’s why I’m back.”