Ask the Mechanic

No Playing With Chaffer Sieve

(Steve Thompson)

READER: I have an International 1666 combine that works great, but we have had problems with the combine breaking the chaffer sieve when the right rail that holds the chaffer breaks. We have to replace this sieve once every season. International has used the same hanger assembly design for years, and it seems that it is not a big problem area. We have changed the bushings on both sides, but that did not fix the problem. All help with this problem seems to tell us that we have worn hanger bushings. Do you have any ideas? The chaffer sieve and rail are expensive, and I'm getting tired of crawling up in the back of the combine to fix the problem. It's hot in there.

STEVE: The hanger assemblies for the sieves are really a great design. However, any assembly that has a start-and-stop movement back and forth must have no play and are usually mounted on rubber bushings. Rubber-mounted bushings like you have on this combine do a great job of absorbing shock when the arm stops and starts. In good grain, the weight of the grain on the chaffer sieve is very heavy, and it compounds the shock that must be absorbed by the hangers. I have seen your problem a time or two, and I bet what you have here is a worn arm and bolt that fits in the arm on the opposite end of the bushing. It is hard to recognize the play in this area, because when removing and installing the sieve and broken rail, as you know, it is a tug, push, pull, shake -- and whatever else you can do -- to remove the heavy sieve and rail. This procedure makes it very difficult to detect any play in the arm. Looking at the photo above, you will see the worn hole and bolt that has caused the problem. That much play will break the rail that sieve runs in, and then the sieve is loose and breaks apart.

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-- Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email mechanic@progressivefarmer.com

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