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The concave adjusting cylinder on the right side closes by itself while I'm combining. The left side will stay where I set it.

In canola I set it to 20 mm and by the time I get to the end of the field the right side is closed all the way.

Anyone have this problem before? Thanks.
 

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450 concave

This has happened to me a few times if the crop is not set, but not only on one side. Did you try setting the crop to canola? Sometimes I have to open the concave all the way, close it all the way down, then open back up to the setting want. Seems to stay then.
 

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on 400 series the concave cylinders can get an internal leak. Since it is closing it may be a valve leaking.? These things will drive a person crazy chasing settings. Let us know what you find. Goodluck Tigercat
You are on the right track Tigercat. The 400 series uses phasing cylinders for the concave clearance. I think master on the right and slave on the left. Like any master/slave combo they have to be phased occasionally. I think that is one reason the concave clearance is supposed to be cycled all the way both ways every day at startup. If all the internal seals are holding, it should hold the concave level for the day. If the piston o-ring is leaking then one or both rams will go out of adjustment and no amount of adjustment will fix the problem. It needs rebuilding or replacing. My 480 had the same problem going out of adjustment and I decided to pull the master ram apart and everything inside looked really good , except a little valve right in the center of the piston. It looks like the head of a nail with the long part only 3/8" long. There is supposed to be a rubber seal around the head of the nail that seals oil from going through a small hole in the center of the piston except when the piston is all the way to the bottom of the barrel, when the little nail hits the bottom of the barrel before the piston and unseats the valve, allowing oil to bypass and rephrase the 2 rams. It was not too bad a job to replace the little "nail head valve" and only cost about 10 bucks. You can get a seal kit for a complete rebuild but I did not see the need for that and the little valve and main piston o-ring fixed my problem.
 
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