The largest shredder SSI Shredding Systems makes, a 700 hp diesel powered monster that’s track mounted
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A primary reducer at work in a landfill makes
its own diesel power. Diesel driven machines shine in disaster zones where electricity is merely a memory.
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for portability, can chew every hour through 150 tons of tree limbs, house scrap—even engineless automobiles. While motor blocks big or small might be a bit more than the machine can swallow, little left behind after September’s Katrina-sponsored Gulf coast shred fest would as much as make it belch.
Anticipating a need in the hurricane’s aftermath, the company inserted a “special” order into its production run for a diesel engine shredder—more properly, a “primary waste reducer,” according to SSI senior product engineer, Mark Fowler. Shredders produce small chips, while reducers make big items into a size that can be better managed in a landfill.
With three orders for paired pumps already on the books at supplier Parker-Denison, SSI was able to convince the company to bump up delivery from about one pair a month for a calendar quarter. Instead, all three pairs shipped to SSI in October. Parker’s distributor, Hydra-Power Systems, was instrumental in encouraging the factory’s quick response.
Good lead times are one of the cements binding the SSI-Parker business relationship, Fowler says, along with unusually large displacements in its line of axial vanes pumps, amounting to 30 and 24 cubic inches per revolution in its two biggest units.
Another handy feature were the line’s 9A controls, Fowler adds. With them, the pump swash plates can be varied electronically, trading, as Fowler puts it, “speed for more torque” when particularly gnarly scrap hits the cutting blades.
“Most of the time the pumps are not seeing anything close to relief pressure,” Fowler explains. But when the chewing gets tough, an analog signal from a dual-output transducer tells the PLC to destroke the pump. A second channel from the transducer sends a digital signal along to the PLC, which watches pressure for a user-defined time interval. Once that interval is exceeded, the PLC reverses the pump direction to spit the object out for a retake. The number of times this can happen before an operator is dispatched to remove the unyielding piece can also be set by the user.
As is the way of good intentions everywhere, an order for the scrap muncher has yet to come from any of SSI’s Gulf states customers, who themselves are probably mired in a bureaucracy more entangling than anything Mother nature ever dreamed up.
Web resources
Watch SSI’s Shred of the Month, at http://www.ssiworld.com/watch/shred.htm
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