PTO shaft damage on a spreader. Why did this happen?

[HCJtractor]

Hooked up my cone style fertilizer spreader to my 3 point hitch yesterday. It is fairly new, used last Fall. The telescopic drive shaft connecting the spreader to the PTO was stuck and wouldn't telescope. I couldn't budge it. Figuring it was corroded from sitting a season, I finally had to pull it apart with a chain attached to both ends. When it broke free I discovered why it stuck. This shaft is not the standard oval shape but instead made from square tubing, one sliding into the other. The first 1/3 of the inner shaft was twisted about 15 degrees, not bent or dinged but perfectly twisted. So when the shaft was telescoping to its shortest length, it seized up very tightly. So I've lost about 1/3 of the range of motion. Rather than trying to weld on new tubing, I bought a whole new assembly.

My question is why this happened? What could I have done to cause this? It seems obvious that the power of the PTO twisted this, but the gearbox spins freely, so it is not locked up. Could just the resistance of fertilizer clumps bind the agitator enough to cause the shaft to twist that much? I want to make sure I don't repeat this on my new assembly.

 

[Tx Jim]

When you engage tractor pto do you have tractor engine idling or just above idle or WOT?

 

[HCJtractor]

When you engage tractor pto do you have tractor engine idling or just above idle or WOT?

I honestly don't remember but I would think I have enough sense to lower RPM before I engage it. And also my buddy spread some with it last year. But I see what you mean. Perhaps the sudden torque could have twisted it over time. The shaft I bought at Tractor Supply has an oval type shaft, more like what's on my rotary cutter, but smaller. Hopefully it's stronger.

 

[Baby Grand]

It twisted from a torque overload, either from shock due to engaging too quickly at high speed, as Tx Jim mentioned, or due to something temporarily jamming the spreaded's rotor - maybe from clumps, like you mentioned. Is there a slip clutch or shear pin in the drive line? If it has a clutch, the clutch needs to be "slipped" on a periodic basis - probably more often on a spreader of anything corrosive.

 

[HCJtractor]

It twisted from a torque overload, either from shock due to engaging too quickly at high speed, as Tx Jim mentioned, or due to something temporarily jamming the spreaded's rotor - maybe from clumps, like you mentioned. Is there a slip clutch or shear pin in the drive line? If it has a clutch, the clutch needs to be "slipped" on a periodic basis - probably more often on a spreader of anything corrosive.

no. There is no clutch or shear pin that I can see. Hopefully the new one is stronger. But I will be more careful to lower the rpm when engaging. But can't do much about clumpy fertilizer. Thanks for the replies!

 

[CobyRupert]

I honestly don't remember but I would think I have enough sense to lower RPM before I engage it. And also my buddy spread some with it last year. But I see what you mean. Perhaps the sudden torque could have twisted it over time. The shaft I bought at Tractor Supply has an oval type shaft, more like what's on my rotary cutter, but smaller. Hopefully it's stronger.

Was he the last to use it? Did he use his own tractor? Seems like it wouldn't of telescoped when it was taken off. Would of put some strain on the pto shaft when the last operator tried to work the 3 pth.

 

[jimmysisson]

If another tractor powered it, maybe the driveshaft was extended more than it could handle, and more than it was on yours.
Jim

 

[Texasmark]

I think that the agitator that is on the shaft and has the roller that runs around inside plus doing as Jim and others pointed (engaging PTO at too high an rpm) out did it, especially if the hopper was full. Caking as mentioned would surely aggravate the condition.

It's easy to see why there is no shear protection in the drive line. One just wouldn't expect much of a load on the line. Course the PTO shaft has to be rated for the drive HP also. Mine seems to be. The smaller the tractor the better. I run mine with my 30 hp Ford 2000 and since I have a tranny driven PTO it can't help but start slow.

Other thing I use as a motto: Don't lend your equipment!

Mark

 

[HCJtractor]

Was he the last to use it? Did he use his own tractor? Seems like it wouldn't of telescoped when it was taken off. Would of put some strain on the pto shaft when the last operator tried to work the 3 pth.

It was last fall so I don't remember, but at the time, neither of us noticed a problem. And perhaps I could have removed the shaft without noticing it wasn't telescoping. And it only locked up at the shortest position so it probably worked ok at normal operating height but of course you still need a little play at the shortest point which we obviously did not have. So guess I'm happy the shaft was all that was damaged, rather than the tractor PTO shaft or the spreader gearbox.

 

[paulfun9]

If your friend used it on an other tractor and the shaft wasn't the correct length for it Binding could have occurred and just enough to cause the problem.
I do loan some of my attachments to friends but am very selective about it and any PTO driven ones I personally hook up to their machines so that I can check the fit of the shaft on their machine.