Quiet. That’s not the first word that normally comes to mind while watching the Allu Model AS 38H windrow turner attack nearly 200-ft. (61 m) long windrows; but standing 50 ft. (15 m) away from this behemoth of a machine, it sounds no louder than a small truck. The unit is run by a 450-hp (335 kW) Mercedes-Benz turbo diesel engine, and the same engineering qualities go into its diesel motors as into its cars.
Capable of turning windrows 10 ft. high (3 m) and 26 ft. wide (8 m), the outside augers on the 7.2 ft. (2 m) diameter drum pull the material in toward the center of the drum. The cutting edges on the augers are replaceable. The center mixing section lifts the material up and over the drum, laying down a thoroughly mixed and fluffed-up windrow that is 12 in. (30.5 cm) taller than the original.
The City of Greensboro, N.C., uses this machine to make short work of 32,000 tons (29,030 t) per year of collected yard debris — brush, ground-up stumps, leaves and grass clippings.
Greensboro has owned and operated a yard debris composting site at its White Street landfill for the past three years (it was a privatized facility before that). The White Street landfill started operations in 1952 and was once on the outskirts of town, but is now surrounded by residential development.
The city uses the Allu model AS 38H windrow turner on a 20.3-acre compacted earth pad within the boundaries of the White Street facility. Incoming yard debris is ground up by an outside contractor, and Lewis Walker, the facility operator, uses a yard truck to move ground-up material into windrows.
Like many outdoor yard debris composting facilities, the amount of time it takes to create finished compost depends on the amount of rainfall and the seasonal nature of yard debris, but can take up to 7 or 8 months.
“I use my Allu to turn these windrows about twice a week if it’s been raining,” said Walker, “otherwise, without rain, I’ll only turn every two weeks or so, so that the windrows don’t dry out.
“This Allu is much better than our old machine because of the way it fluffs up our windrows to keep air in them. It’s also got lots of torque. I’ve never had a problem with it bogging down in a windrow. Plus, I can dial down the drum to get it to within one inch of the ground, so I can gather up and turn all of my windrows and not leave that small unturned area at the bottom.”
The Allu model AS 38H comes with a variable-frequency drive unit that coordinates drum speed and turner speed, so that if the drum encounters resistance, the turner slows down. This minimizes damaging shearing forces on the machine. When the resistance is removed, the turner speeds back up automatically.
Greensboro ordered the Allu with the cab fixed in the middle of the machine (it normally sits on one side where it can adjust up or down by almost 5 ft.) to make sure the operator had good visibility of the operation.
“I have no problem seeing what I’m doing up here,” said Walker. “It’s a very comfortable cab to work in.”
Greensboro ordered the Allu model AS 38H with tracks as its compost pad is compacted earth. The Allu comes with heavy-duty tracks that are 20 in. wide by 74 in. long (51 by 188 cm).
The unit also has horizontally adjustable main plows on either side that can help feed wider windrows in towards the center.
Rob Rash, the compost facility manager, bought the Allu Model AS 38H in August 2007.
“We got three bids for turners when we did our procurement,” Rash noted. “Allu was the lowest responsible bidder. We ordered the Allu with an extended warranty and with an inventory of replaceable parts and we get the machine serviced by an outside service contractor. Operationally, there is less to monitor about the machine’s condition than with our old turner because so much of it is computer-controlled. We don’t have much need to move this turner to other sites, but it does fit on a low-boy truck without needing oversize load permits, which is a good design feature. Overall, I like this machine.”