Mining and earth-moving operations around the globe have inspired some of the largest, most powerful machines ever designed and built by man. These machines involve millions of parts and sub-assemblies and can weigh on the order of close to 500,000 tons. They are designed to be mobile too, and they are built to withstand the harshest, outdoor environments on the planet, while under almost constant use.
And the hydraulic systems these machines use…wow. They’re really, really big.
One of the most innovative machines used in mining may be used for a technique known as Highwall Mining. In the old days, once surface mining had taken the majority of useful minerals from just below the surface, the law of diminishing returns dictated that as the machines moved farther and farther away from the core deposit where the density of target minerals became less, the economics of continuing full strip mining, or open pit mining become less and less attractive. Yet these area’s still contained millions of tons of useful raw material (typically coal).
To drill directly into the “high walls” left by surface mining in an economic way, requires specialized equipment. Highwall mining is actually a hybrid of surface and underground mining technologies. It is a people-free, low footprint mining process which uses high power hydraulic cylinders as part of a Pushbeam Transfer System. In this system, high power hydraulic cylinders advance the cutterhead into the coal seam on the highwall. Every 6 meters, a new conveyor belt segment is inserted between the Pushbeam and the cutterhead, allowing it to advance another 6 meters before the next segment is inserted, etc… Use of this system constitutes a great improvement on traditional high wall mining techniques like auger mining because the pushbeam system can penetrate nearly 1600 feet into the coal seam, with much higher recovery.
For a fascinating explanation of this marvel of mining engineering, see this video.
Big Mining Hydraulics Need A Tough Linear Position Sensor
Our end client is the the Addcar Company of Kentucky USA who designed and manufactures the Addcar Highwall mining system. The specifications of the hydraulic cylinders used on this intricate machine, are impressive to say the least.
STROKE LENGTH: 19.8 feet (5.8 meters)
WORKING PRESSURE: 200 bar (~3000 psi)
HYDRAULIC POWER: 400 hp.
To really understand the awesome power of these hydraulics, consider this: the hydraulic pushbeam system must be able to push the cutterhead up to 1600 feet into a solid wall of rock. It has to push the weight of hundreds of 6 meter conveyer segments as well as applying force to drive the cutterhead at the end of this chain, into the wall. Then it has to retract them all when the vein is fully dug.
CPI Draw Wire Linear Position Sensor Solution
The Hydraulics used in this system were retrofitted to accommodate our SL2000 linear position sensor, by designing a modified end-cap per CPI instructions for in-cylinder mounting. This extended end cap allowed the CPI sensor to fit in the cylinder with the head of the short rod transducer providing easy connectivity to standard electronic interfaces.
The CPI SL2000 is a hybrid sensor, part high-tech draw wire, part magnetostrictive transducer. For our draw wire sensor, a stroke of 6 meters is no problem at all. Our SL2000 provides critical position feedback into this application, improving the overall reliability and operational control of the system. No other hydraulic cylinder linear position sensor in the world can reliably handle such long stroke lengths while maintaining such high reliability. Add to that our IEC-EX and ATEX intrinsic safety ratings, and the complete waterproof, pressure tolerant nature of our sensor assembly, and you have the perfect solution for position sensing in long stroke, high power hydraulics.
CPI Hydraulic Linear Position Sensors Are Built To Last.
Into the toughest applications in the world, go all our switches and sensors. It’s what we do. For more information, please contact the CPI engineering team directly through the website.