Combines Help Rotor speed slows down

I know nothing about an R72, but when I had a similar problem with the R60, the cause was a leaking O-ring in the cylinder inside the drive sheave. Replacing it wasnt as bad as it sounds. Good luck!

I think your right on Tom. We had the same thing happen to us once. Agree, that the fix was pretty easy too.

Before you tear up the variable speed on the mainshaft, go around to the other side and make sure your main drive belt coming from the engine is tensioned correctly. The rubber snubber can be setup wrong and keep the belt loose. This has happened several times in the past.

If it was an oring you would have major external leak. Must be sliping belt or clutch beings it comes back up to speed with reduced load. Sounds to me you covered what could cause cylinder belt to slip. I'm leaning toward other side like kelly said. Be sure the nuts on threaded rod for main drive belt snubber are locked together at top of threaded rod. Make sure both electric clutches are pulling. If only one is pulling it would get very hot quick when slipping. You could shut down machine after you had it slipping and then fell outside clutch plate carefully and then reach around back side of pulley to feel inside clutch plate carefully. If only one clutch is pulling you would likely notice it being a little draggy to get turning when you first engage clutches. If only one clutch is tring to do all the work you would likely have bad wire between the clutches. If both clutches are slipping I would consider brusholder or currant supply to it may be low. Hopefully you got her going before you read this message. Have a safe harvest.

Well, the good news is it is working now. Discovered the nuts on top of the threaded drive belt were in the incorrect position over the rubber, so kind of difficult to say whether that alone fixed it or repacking the variable speed sheave and adding a stronger spring. It was time to repack by the look of things and also ended up buying a new hub since the splines were almost twisted in two. So all's well that ends well (about $1000 dollars later!).

One important thing to note when problems lke this occur is.......what else slows down. Is it just the cylinder........only the machine.......or does the engine slow down alsoIJ........Glad you found it. Those little nuts on the snubber have caused a lot of problems. A lot of farmers and mechanics alike didnt understand what they did and moved them to close to the bracket, keeping the belt from getting tight under load.A couple years back I talked with a cutter down in Texas that had his local dealer working on his combine. They had done the pump, injectors.........and a ton of other work only to not fix his HP problem. He had lost a lot of time and spent a lot of money and was frustated to say the least. Dont remember how he found me but he had wanted me to make the trip from Oklahoma to south Texas to work on it. I got him calmed down and sent him out to look at those nuts.........he called back and couldnt beleive he had spent thousands of dollars to fix a problem I sent him to and he fixed in a couple minutes.........Right after I went to work here in OK a farmer traded a combine because of lack of power. It had been to the shop a bunch of times.......pump and injectors done several times.....it seems it would be decent for a short time and then just get weaker and weaker.I walked out to the combine when it came in on the truck and showed the salesman what was wrong.......It turns out the mechanics in the shop didnt know how to set up some thing as simple as the little rubber snubber on the mian drive belt. I made that same service call too many times in the first couple years I was here. Too many times they are in the wrong place.Some thing all Gleaner owners should be aware of. Van

U need to put a poppet kit in the valve stack for your rotor speed up and down make sure you get the right size of orface in the right valve. most likely your getting a leak around the small o ring on the orface_seat in the poppet.

I think you have the problem peggged. I have had this happen numerous times. The idler HAS to be able to follow th slack in the main drive belt.