Rugged gearboxes and motors keep conveyors moving at a Montana coal mine

Dec. 18, 2013
Rugged gearboxes and motors keep conveyors moving at a Montana coal mine

The motors and drives for conveyors played a major role in the decision to reopen the Bull Mountain coal mine in Montana. They were crucial for efficiently delivering up to a million tons of coal per month. Siemens Industry Inc., Johnson City, Tenn., supplied the gearboxes and drives, which could keep the 60-in.-wide belts carrying 5,000 tons/hr moving without overtensioning or inducing dynamics waves in the belt.

Some of the conveyors at the Signal Peak coal mine in Montana carry 500 tons of coal/hr for over 22,000 ft.

In one of the mine’s conveyors, a Siemens Flender right-angle alignment-free 24:1 ratio gearbox takes power from four 500-hp motors with air-cooled variable-frequency drives through a PLC. Operators monitor and control the belt using two control panels that keep them updated on the belt’s tension, torque, speed, faults, trends, and alarms. Sensors throughout the mine connect to the panels through fiber optics. The gearbox and motors are supported by a pulley shaft through a rigid coupling with a single torque arm for vertical support. This makes it simple to move the power units, which happens regularly when seams get tapped out and operations move to another portion of the mine.  For example, the alignment-free drive alone cuts reinstallation from three days to half a shift.

The gearbox is also quieter than similar
units, so operators know the gearboxes are functioning smoothly and not ready to breakdown. And the gearbox’s reduced noise levels make for a safer and more-comfortable working environment for miners. A ribbed housing and fan lets the compact gears run 30% cooler.

Over the past year, the mine’s 300 employees have relied on the conveyors to move more than a million tons of coal per month with 98% uptime, exceeding the industry target of 95%. The plan is to use the conveyors and motors for the next 25 years at the newly renamed Signal Peak mine as it yields over 300 million tons of coal, less than a third of the mine’s total capacity.



Signal Peak Energy

Sponsored Recommendations

Pumps Push the Boundaries of Low Temperature Technology

June 14, 2024
As an integral part of cryotechnology, KNF pumps facilitate scientific advances in cryostats, allowing them to push temperature boundaries and approach absolute zero.

The entire spectrum of drive technology

June 5, 2024
Read exciting stories about all aspects of maxon drive technology in our magazine.


May 15, 2024
Production equipment is expensive and needs to be protected against input abnormalities such as voltage, current, frequency, and phase to stay online and in operation for the ...

Solenoid Valve Mechanics: Understanding Force Balance Equations

May 13, 2024
When evaluating a solenoid valve for a particular application, it is important to ensure that the valve can both remain in state and transition between its de-energized and fully...

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!