Cub 3000 series
 

Can anybody tell me why I am having a endless problem with my pto belt that keeps falling off the bottom part of my pto engine pulley even though the shoulder screws are always tight and close to pulley.

This has been an on going problem, i think i've tried adjusting just about everything even bracket idler that falls on the belt to hold the tension with no avail. The belt is fairly new, but on engaging alot it seems to just come of, thus makeing me constantly loosen the shoulder bolts to reinstall. I cant tell all the time when its off unless I get off tractor to see it hanging, Can anybody offer any insight? much appreciated, thanks john.:bash2:

I do not have a lot of experience with the 3000 series but a couple of things to think about. Are the belts factory belts? The factory belts are the best for your mower. My dad tried to save a few bucks one time and had nothing but trouble. Are the pulleys damaged in anyway? Good luck.

cub 3000
 

thanks so much for your input, the one currently on there is a sten belt, i have had the original belt, but is the same. the large engle does have some small play mabye 1/16th, But thats the only thing i havent changed yet.

extremely puzzling
 

thank you so much for your in put, mabye 1/16" play in the large engine pulley, they seem to be ok otherwise.

I've seen several of the double pulleys on the 3000 Series PTOs be way out of whack. Take the pulley off the PTO shaft (snapring there) and look at the space between the two pulleys. It should be pretty much even all the way around. If not, you can pry between the halves to get it to run true again.

I also second the motion for OEM PTO pulley belts.

I've not had any problem with mine yet. Can you check the alignment with a string to see if they are running true? I've also seen where the bottom pulley can get bent. Does the belt have any wear marks on it from not running correct? Is the actuator causing the belt to come off. If you can take some pictures and maybe we can see something causing your problem.

Thanks so much, do you mean in back of pulley on shaft to the engine? John

Hi thanks much for your help, there is some wear, a little but there is some, I will change that belt again. I haven't checked the alignment but with a string, good idea, the lower pulley does have some play I didn't think enough to make belt come off, but mabye so. It only comes off when i engage the mower deck, every so often.

The secondary PTO drive pulley that drives the deck. It's made of a thinner steel material than the engine PTO pulley and may be a tad warped. Mine is, but it doesn't cause the belt to pop off. Just make sure it isn't excessive. If so, you can remove it easily and pry between the two halves of the pulley to straighten it out.

Just another thought....have you greased that center fitting for the axle/PTO? It's a commonly missed grease fitting. If its left dry, it can cause the PTO bearings to heat up. Also make sure the deck is properly lubricated and that its rotating assembly moves easily as well.

Hi, yes thanks much again,Ive always greesed the complete deck and the center pivot, idler pulley freezes sometimes, but i still manage to get the dreese in. i will give this a shot with the puleys, i understand, thanks so much

Good thing I read throught this post as I did not know the idler pully had a grease cert, will be going over my 3235 in prep for winter snow duty.
Had all but forgotten about the axle piviot /bearing race, will need to shoot some fresh grease in that on also.

Never had the belts fall off though, have burnt up a couple sets useing the tiller, and the OEm belts are not cheap.

Went to grease the PTO and idler pulley bearings, found no grease certs.
Called my local dealer, found out they are sealed bearings.

I have a 3165 and have had the same issue since I got the mower, I have tried a new pulley but it still jumps off, I ended up just taking the shoulder bolts off for ease of putting the belts back on. Just my two cents on the subject.

The deck idler and tensioner pulleys are sealed bearing style setups, this is true.

The spindles, tensioner pivot, driveshaft, and PTO all need greased regularly.

As for the jumping belt....any insight yet into the accompanying symptoms? Its a very simple design, there cant be too many factors that contribute to the problem.

I had this problem after I had my engine out to do some internal repairs due to previous owner neglect. Still to this day I have now idea why it started after I had removed and installed the engine, but my solution was a thinner spacer on the engine between the crank pulley and the crankshaft.

Had to custom make one about half the thickness of the original. Havent had any problems since.