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Rebuilt Concaves Boost Efficiency 15 To 30%
"No matter how well you fine tune a machine, you won't reach maximum capacity if the concave isn't true," says Bill Schwerin, Walla Walla, Wash., who built his first "precision tuned" concave several years ago when custom harvesting.
FARM SHOW first learned about Schwerin and his concave-trueing operation from Ray Steuckle, Caldwell, Idaho, well-known combine expert and author of "Combine Settings For Better Harvesting". According to Steuckle, "Schwerin's concave is as good as it sounds."
Schwerin got the idea for his concave as a custom harvester. Like most operators, he was having difficulty getting enough capacity out of his machines to cover enough acres to make a profit. He was faced with either putting too much grain out the back of the machine or slowing down.
"I turned to Ray Stueckle who had worked out procedures for setting and fine-tuning most makes and models of combines. I found that no matter how well you fine tune a machine you won't reach maximum capacity if the concave isn't true. Ray challenged me to build a better concave so I came back to the shop and began experimenting."
Schwerin bought lathes and other special equipment and began rebuilding his own and other farmers' concaves. Now he has concaves coming in from all over the U.S. and Canada for reworking. He also manufactures concaves which, he says, virtually eliminate walker loss in small grain crops and improve overall efficiency 15 to 30%, depending on the overall shape of the rest of the machine. He says this holds true on most new combines, too.
When a concave arrives at Schwerin's shop, the rods are pulled to allow spacings of at least 1 1/2 in. between each one. The vacant holes are welded shut with plugs. All the wires are pulled on some models and every other one on others. Next, strips of high strength steel are welded to each bar and the first four slots between the front bars are closed up. The concave is then ready for the lathe where it is bored out to within .005 of an inch of a perfect circle. The edges are then smoothed to finish the job. A grower can request to have the concave chromed as chroming doubles the life of the concave and doesn't interfere with the threshing process, according to Schwerin. He also offers a shim kit for the machine's cylinder and sends complete instructions with the kit for installation.
"On most concaves the bars are not set at a uniform height nor in a true circle. These imperfections in the concave affect both the quality of the grain harvested and capacity of the combine. Separation area is lost and cylinder speed must be increased to obtain good thresh and separation. The bottom line is lost dollars in grain out the back of the combine," says Schwerin. "On our concaves all of the bars are bored to a uniform height to form a true circle. This lets the operator set the concave at 0' tolerance at the rear, creating an uninterrupted wedge from front to rear. It is designed to do the job up front where the work should be done."
Schwerin says that with his concave and Steuckle's recommendations, small grain producers are able to obtain a 20 to 30% increase in efficiency. The benefits in corn and soybeans are less.
The cost for rebuilding concaves ranges from $500 to $750. Schwerin-manufactured concaves sell for $570 to $845.
For more information, contact: FARM SHOW Followup, Schwerin Concaves, Inc., Rt. 5, Box 314A, Walla Walla, Wash. 99362 (ph 509 525-7556).


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1984 - Volume #8, Issue #2