Combines rotor speed

bob,are the sheaves on your rotor drive belt pushing up against the belt hardIJ are the sides of the rotor drive belt shining if it is the belt is probably slipping,check the spring on the top sheave it might be stuck. john

Another possibility is the o rings on cly. drive could be cut or leaking by .

is it slowing down and staying slow or just slippingIJ Suggest top sheave torque cams bad. Only thing I know is to replace on the old 50's. Any other fix to torque cams prior DanIJ

Thanks Tbran, Johnboy and Acre eater. The rotor slows in heavy crop but quickly recovers, once you slow ground speed.. I suspect this is slipping. The mchine is a 1987 model. When we cleaned the upper sheave around 2 seasons ago it was really full of dirt, we also noticed that at some prior time (we purchased 2nd hand) the clutch must have done a fear amount of slipping as there looked like a fear amount of wear. I am not sure how hard the belt is pushing against the sheaves. You can squeeze the belt together in the middle and it doesn't pull back.The belt is not too shinny. last season had the o'ring in the gear box repaired (cylinder side)as it was leaking.

a slipping clutch will emit sparks and will be HOT!!! you won't have to guess if it is slipping!

So what you are saying Tbran. Is if the engine is under pressure a different voltage is put out which makes the rev counter move about......is this correct. Sounds like the belt is the slipping but not the clutch. Should hear the clutch in any case. Movement on meter is about 150-200 revs whilst over 1000. Will check again the torque cams. thanks

First of all it is very important to grease that torque sensor on top set of varible sheaves daily and cycle varible all the way fast and slow daily. The grease lubes the surface between sliding hubs and then bleeds off onto the torque sensing cams. Cycling the speed will spread out the grease and prevent scratching or scoring on the cams or hubs. You need to pull off torque sensor and then the sliding hub. Clean up sliding hub and check the clearance where it slides on torque tube. There should not be any scoring and the clearance should be inbetween .006" and .010". Any tighter or looser you could have a sliping belt problem. I have not sean them dementions printed anywhere but it is the numbers I have came up with for any torque sensors that I have been around. I have used a cylinder hone when clearance is to close and checked it with fealer ribbon. We had a spring and cam assembly for torque sensor on hand for about 10 years and finally sent it back. To answer Tbran about spring can and cams. Yes I have taken one apart. I ran the hydraulic press down aways and then onto large hex on can assembly. With a little presure on hex and plenty of room to let spring loose I cut the areas between the holes in can. I had scribed a line to get back together the same way I took it apart. Once you have it tore down and all cleaned up you can polish cams with DA sander. If scored or groove badly you may be best to just replace the assembly. You should not attempt pulling one of these spring cans apart unless you fully know the dangers of spring loaded assembles. I would check you cylinder speed sensor clearance also to be sure that all the legs are close to sender without touching. Good luck

We have had similar problems here in Western Australia during the past season. We found the top sheaves had glazed and would not grip on the belt. After changing the sheaves the problem dissappeared. Just by turning the rotor pulleys you could hear the friction between the belt and pulley. We are not sure if the sheaves have been machined correctly or hardened properley.

Had same thing happen on my R-70. In order to slow it down simply remove the 4 v_s cylinder studs. Clean out the dirt or sand each stud and be sure not to lose washers. The v_s cylinder pulley should slide freely. Hope this helps.

Thanks for the help.