There were longwall shearers before it and more sophisticated, more powerful machines after it, but no longwall shearer has had the popularity, sustainability and longevity of the Joy 4LS shearer, Joy Mining Machinery reports.
Celebrating its 20th anniversary of mining coal around the world, Joy Mining Machinery has rejuvenated the 4LS shearer with the model 4LS20, a machine specifically redesigned for the Russian and Polish coal industries where demand is for reliability, capability and economy.
Since first introduced in July 1986 at American Electric Power’s Martinka Mine, the 4LS shearer has mined literally billions of tonnes of coal in seams ranging from 1,320 mm to more than 4 m thick in virtually every country in the world employing longwall mining: the USA, UK, Australia, Canada, Poland, South Africa, Mexico, Japan, Norway, China, Russia and Slovenia.
Joy Mining continually improved on its pioneering shearer designs, building ever more advanced, more productive machines since the introduction of the first model 1LS shearer in 1975; that machine evolving into the 2LS, 3LS, 4LS, 6LS and, now, the 7LS series of shearers, including the 7LS7, capable of single-pass mining the thickest extraction in the world today.
While continuing in their efforts to design the most sophisticated, technologically improved shearers in the industry, Joy engineers also have recognized that the needs and demands of the Eastern European and Asian longwall mining industries were not the same as those in the ‘West’, where the emphasis has long been on larger, more powerful machines capable of producing ever-higher tonnages.
In Russia and Poland, a machine was needed with a proven performance record that offered technology specific to their requirements of increased productivity and lower operating costs within existing mine infrastructures. And Joy engineers knew no machine had proven itself in more places, under more varied conditions and over a longer period of time than had the 4LS shearer.
Joy already had established a significant market presence in Poland with the 4LS shearer. The advent of Joy’s 1,000 V AC variable frequency drive—OPTIDRIVE—allowed Joy engineers to design into the 4LS shearer a more powerful haulage unit with JNA controls; thus creating the model 4LS20, a competitively priced machine that featured Joy’s high quality-leading expertise but at a slightly lower power than the state-of-the-art JOY 7LS shearers; a machine designed to accommodate the continually developing longwall mining industries of Eastern Europe and potentially China.
Joy’s OPTIDRIVE integrates the AC variable frequency drive’s electrical and mechanical systems and its software. Where the motors and drive in the OPTIDRIVE system are designed for each other, Joy controls the technology to ensure a compatible system that maximizes utilization of both components, as opposed to using industrial off-the-shelf components modified for underground mining.
The major advantages of AC drives over the traditional DC drives are that more power can be provided to drive the machine in the same space previously occupied by the DC motors. In addition, the brush-less AC motors eliminates the time-consuming and expensive maintenance associated with DC motors and the possibility of contaminants entering the motor when brushes were changed, as was the case with DC motors.
A significant bonus to incorporating OPTIDRIVE into the 4LS20 is that those opting for the new design have the benefit of an AC variable frequency drive that is interchangeable with all other Joy underground mining machines: shuttle cars, continuous miners, longwall shearers and flexible conveyor trains, the exception being the software brains of the system that bring unique attributes and advantages to each piece of equipment.
As a result of replacing what had been the standard DC haulage on the 4LS shearer with the AC OPTIDRIVE on the 4LS20, Joy allows the use of a mine’s existing 950 or 1,100 V primary voltage source, thus saving the mine operator the additional expenditure of changing the incoming voltage source to 3,300 V. Additionally, the 4LS20 has an increase in total horsepower from 425 to 698 kW, haulage pull from 44,452 to 61,235 kg and total weight from 30,844 to 40,370 kg. At the same time, increasing the shearer ranging arm length from 1,930 mm to 2,362 mm increases the cutting range from up to 2.8 m to 4.3 m.
Over the years, Joy incrementally increased the power output from the 4LS shearers. The original model 4LS1 shearer used 26 kW haulage motors, later increased to 37 kW. With the advent of Joy’s AC OPTIDRIVE, the haulage ratings further were increased to 60 kW. Over the same period of time, the cutter motor output on the 4LS series shearers had been increased significantly, from 179 kW to 421 kW today. Eastern European and Asian longwalls often use a 283 kW cutter motor in order to operate comfortably on 1,000 and 1,100 V.
Integrating and controlling the improved electronic, electrical and mechanical features of the new 4LS20 is the JNA. JNA incorporates the latest technology of today with the ability to integrate the breakthroughs of tomorrow while creating an evolutionary path for ease of system upgrades to complement the rising sophistication inEastern European and Asian longwalls, including diagnostics, face equipment integration, underground data logging and surface data communication linkage.
Combined, these latest advances in the 4LS series of shearers offer the immediate benefits of increased production, improved productivity, and lower operating and maintenance costs with only minimal retraining of personnel to familiarize them with the improved, yet simpler, haulage system and controls while at the same time providing the platform to incorporate tomorrow’s technology. The JOY 4LS20, a unique machine designed to meet the needs of a unique market.
Joy 4LS20 shearer delivered to the Raspadskaya mine in Russia.
