Newbie Question: Can't disengage the PTO with the mower still spinning

[americandogma]

So I am certainly a tractor newbie (especially when it comes to larger tractors greater than 25 HP).

I was test driving a Massey 261 (60 HP, 53 HP PTO) yesterday from a private seller and everything seemed fine. A 7 foot 3pt rotary mower is included with the sale.

The only thing that surprised me or more importantly made me reluctant to purchase was the fact that with the clutch fully engaged the PTO would not disengage until the rotary mower stopped spinning. Since the mower stopped spinning I assume everything is OK with the PTO Clutch or brake or whatever BUT is this normal?

Should I be able to disengage the PTO as soon as the clutch is fully pressed without waiting for the mower to spin down?

This might be a silly question but I have never purchased a tractor before and never really used anything bigger than a 4 ft rotary. I appreciate any help or additional info.

 

[PHPaul]

WARNING: I DO NOT KNOW THE ANSWER, I'M JUST THROWING OUT IDEAS HERE!

First thing that occurs to me is that the inertia of the mower blades is actually turning the PTO shaft causing the gears to load up. Try letting the clutch out just a whisker to match speeds and see if the PTO will slip out of gear then.

 

[Fawken]

I've never tried that before since my PTO disengages when the clutch is depressed. Obviously, the inertia of the mower will keep it spinning for some time and I would think it is dumb to try to disengage it while the shaft and gears are still turning.

 

[WM75Guy]

Think of the mechanical parts all in a row: motor -> clutch -> PTO - >cutter. With the clutch out the motor supplies all the power downstream. When you push in the clutch the power is coming from the opposite direction from the cutter spinning down. Can you disengage the PTO? You can but it's still has parts moving. Better to let everything stop moving to avoid wear & tear or catastrophic damage, although it rarely happens.

 

[PHPaul]

Think of the mechanical parts all in a row: motor -> clutch -> PTO - >cutter. With the clutch out the motor supplies all the power downstream. When you push in the clutch the power is coming from the opposite direction from the cutter spinning down. Can you disengage the PTO? You can but it's still has parts moving. Better to let everything stop moving to avoid wear & tear or catastrophic damage, although it rarely happens.

Can't argue with your logic, all I can say is I shoved the clutch in and flipped the PTO out of gear on my JD750 more times than I can count in the 27 years I owned it with no sign of damage.

 

[TerryR]

Better to let everything stop moving to avoid wear & tear or catastrophic damage, although it rarely happens.

How can disengaging the PTO with the clutch in possibly cause damage? In any case, I've been doing it for 18 years with my JD 870 and haven't seen a problem yet.

Regarding the OP's question, does that tractor have a brake on the PTO that's applied when you put in the clutch, putting it under load and thus hard to disengage until it stops?

Terry

 

[americandogma]

Regarding the OP's question, does that tractor have a brake on the PTO that's applied when you put in the clutch, putting it under load and thus hard to disengage until it stops?
Terry

Unfortunately I don't know about any pto brake.

With the smaller tractors I've used and the small 4ft mowers I am pretty sure I have always just stepped on the clutch and disengaged the pto. I figured it might just be that a 7ft mower takes longer to spin down. It wasn't an unresonable amount of time. Maybe 30 seconds.

Maybe I'm over thinking it...

 

[TerryR]

I've not played with tractors in that size for 50 years, so am not familiar with modern versions. But you said you couldn't disengage the PTO until it stopped. That made me think there was a load on the system, which after you press the clutch could only come from the cutter still spinning against resistance, as from a brake, I'd think. I've heard of but never seen a PTO with a brake, but thought that might be the case here.

Terry

 

[JerryK]

I have a 60ish hp J.D. 2240 tractor with about 51 PTO hp. My PTO has always acted like yours when I am hooked up to something with a lot of rotary mass, which in my case these days, is just my 8" wood chipper. If I am running it up around 1800rpm, then idle down the tractor, it is just about impossible to disengage unless I really force it. So, I spool down for a 10-20 seconds, then bump up the RPM's a little [ then push the clutch in ] and she will usually disengage. I think it is a case of the tail wag'n the dog, and probably normal. I don't think there is anything wrong with your tractor, just has a few quirks you can live with....

 

[Fawken]

I imagine it's pretty similar to "power shifting" which I've had to do in emergency situations when a clutch goes completely out on a car or bike. It takes some practice and not a good idea unless you have to. The mere resistance of the hydraulic oil in the gearing would likely act as a pseudo PTO brake and make this a difficult task. I'm going to keep doing like I have been. Doubt there is anything for the OP to sweat on this.