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Scoops and shuttle cars, without a doubt, are the workhorses of any continuous operation, and as such they naturally are a source of endless scrutinizing by opera- tors and original equipment manufactur- ers (OEMs) alike. Both are always looking for the all-in solution to provide higher and more efficient production, safer operation, reduced emission, decreased maintenance, consumables replacement and more. Improvements are being made at the research and development tables and are being brought into design in many of these areas. Even better, nearly all of the industry's major players have been working diligently over the last few years to keep this technolo- gy quite literally at the cutting edge. The aftermarket and rebuild segment of this area is also getting plenty of cus- tomer feedback on needed improve- ments, and the vendor arena is listening carefully. Below are a few examples of this work put into action. Pursuing the Lowest Cost per Ton The concentration for Wisconsin-based Joy Global as of late has been on continu- ing its lowest-cost-per-ton mission, and in the area of its scoops and shuttle cars, that focus has been two-fold and related to hardware. The first is the 550V DC, its variable frequency drive (VFD)-conveyor system is designed to help match up the discharge rate of the shuttle car to the belt infrastructure on which the tonnage is being loaded. "The VFD pump allows for the trailing cable to come under tension at a slow controlled rate when the pump is ini- tially energized," the company said. "This, in turn, reduces the strain on the trailing cable as it eliminates the initial whipping of the cable when it comes under tension." This Joy motor design, which is per- missible, does not require encoders, as the Joy motors are matched and "tuned" to the VFD drive. Additionally, the Joy system requires just two drives to run all four VFD motors. Because there are fewer components loaded into the system, it is easier to trou- bleshoot, resulting in reduced downtime, and the DC VFD's drive enclosures are internally cooled. According to Joy officials, its current proven AC VFD drive units have been redesigned to accept a 550-VDC input, which permits DC voltage to be supplied directly, eliminating the need for any DC rectification internal to the drive unit. Moreover, relocating the DC rectification off the machine allows for a second motor output without increasing the drive unit package size. "That DC voltage is then converted into a variable frequency AC output volt- age between 5 Hz through 90 Hz; this is the same as in the current proven AC VFD drive units," the OEM said. 24 www.coalage.com July 2015 s h u t t l e c a r s & s c o o p s Getting the Scoop B Y D O N N A S C H M I D T , F I E L D E D I T O R The latest in scoop, shuttle car technology Joy's current line of AC-VFD drive units have been redesigned to accept a 550-VDC input, which permits DC voltage to be supplied directly and eliminates the need for any DC rectification internal to the drive unit. New AC conveyor motors from Joy utilize the same mechanical package as the existing conveyor motors.