John Deere 345 lawn tractor mower deck will not reach full speed

[VOL54]

Good afternoon. I have a John Deere 345 lawn tractor with a 54 inch deck. Today when I engaged the deck, it would only run at approximately half speed with the tractor sitting still and the engine running at full speed. The deck would speed up and slow down if I started to move, but would never reach normal speed. Belt usually squeals momentarily when I engage the pto, but that didn't happen today because the deck was running so slow. Never had an issue like this in the past. Anyone have any idea what the problem is? PTO going bad? Battery too weak to properly engage PTO? Belt slipping? Was told by the parts man at my local John Deere dealer that it's most likely not the PTO. He said it either works or it does not. Thanks for your help.

 

[tomplum]

Does the engine seem to have the power and is running at full RPM? Agreed on the clutch staying engaged. Normally 10.5 volts or so will keep a PTO engaged. You like to have full 12+ volts though. Other than that , best get under there and have a look.

 

[DLTTrekkers]

Do not look under it when blade is spinning ! You wil cut your fingers !

 

[gimmodog]

either the PTO clutch is slipping and needs adjusting or the belt is spiipping and needs adjusting

 

[tomplum]

Excessive air gap may keep a PTO from engaging at times, but once engaged has no effect. Once a clutch is engaged the field coil holds it in place. If electrically not enough voltage is maintained to the coil or the coil in the clutch is failing / over budget. Normally you would look down the line from the clutch IE not enough tension due to a stuck tensioner, worn belt, excessive drag on the belt caused by failed or failing bearings.

 

[VOL54]

Does the engine seem to have the power and is running at full RPM? Agreed on the clutch staying engaged. Normally 10.5 volts or so will keep a PTO engaged. You like to have full 12+ volts though. Other than that , best get under there and have a look.

Engine is running at full rpm. It has a less than one year old battery. That being said, tomorrow or Monday I plan on checking the battery voltage to see if that could possibly be an issue. Also plan to remove the deck, check the tension spring, belts, etc. Then try to check out the pto. Other than that I don't know what else to check. I don't want to make the assumption that a new pto will fix the problem. Electrical parts usually can't be returned. So I hope to determine exactly what the problem is before I put out much money unnecessarily. Thanks.

 

[VOL54]

Plan to check out all your suggestions asap. Thanks for your help.

 

[BleedingOrange]

Is there a spring on your mower deck that is suppose to keep tension on your mower belt ? Remove the covers on the mower deck, check both ends of the spring to make sure they are still attached, and make sure grass and build-up isn,t keeping the spring from doing its thing. Check mower belt real good, and make sure it hasn,t worn down and is riding to deep in the pulleys. That would cause it to slip, and act like the belt is to long, allowing it to slip.

 

[VOL54]

Got this problem fixed after I decided to remove the deck. The connecting rod from the lever that tensions the deck drive belt had worn through the bracket holds it in place on the opposite end. And of course I couldn't just buy the bracket, I had to buy the entire assembly, $82 off Ebay versus $100 from local JD dealer. I was out of commission for a couple of extra days, but it worth it save 20%. No big deal in the end. Thanks for everyone's help.