Newbie with PTO problem

[Spoonbow]

Good day all,
Trying to help out my neighbor with her 48 Cub. She has a Woods belly mower on it and the PTO refuses to engage. No grinding/clashing of gears, just a hard stop about halfway through the lever travel. Same behavior in or out of gear, engine running or stopped. She says it had been working fine, but lately it had been hard for her to "push down" (she has a few more years on her than the tractor does). Any suggestions for troubleshooting or possible causes?

Thanks much,
Matt
In the wilds of Benzie County, Michigan

[Dale Finch]

First, try spraying the lever/spring assembly with some PB Blaster (or equivalent), to free up the actual lever.

I often need to ever so slightly release the clutch pedal AS I am trying to engage the PTO. This allows the drive shaft to rotate SLOWLY, just enough so that the splines line up with the PTO clutch collar and moves into place, coupling the drive shaft to the PTO shaft.

There can also be problems with the shift lever pin (inside) being worn, but you need to pull the PTO to check that. The PTO bearing can also move on the shaft, allowing a wider gap between the 2 shafts such that the coupler cannot "reach".

Hope this helps.

[Spoonbow]

Thanks for the reply, Dale. The downstroke of the lever to unlock it from the guide feels a little gummy, but the fore and aft motion of the lever is smooth and easy. About halfway back, it comes up hard against something with an audible clunk (engine not running) and will move no further. Is there a diagram of the inner workings available anywhere to help me wrap my head around the mechanics? I've no experience with tractors, but I had a 40's and 50's British car addiction years back and became quite familiar with manual transmissions and the rebuilding thereof. I've recovered from the illness (mostly), but the knowledge remains.

[Bob McCarty]

Matt, Welcome to the Forum. If you click on Quick Links (upper left of the page), then on PDF Manuals, then on Farmall Cub, then on Service Manuals, then on PTO/ belt pulley, you'll find some diagrams and instructions. Unfortunately, I can't direct link to that section. As Dale mentioned, it's not uncommon for the pin that moves the clutch forward and back to get worn in half and then the clutch doesn't move enough to engage the splines on the shaft. If you remove the fill plug, you can look inside with a strong light and possibly see what's wrong when you move the lever.

[Waif]

In neutral ,(only way I shift the p.t.o. lever) on my 48 the brushhog/deck needs lowered for easy p.t.o. engagement. Odd, I know!
Often it takes using the clutch to turn the transmission shaft a little too if it's feeling stubborn.
I suspect a shaft has a slight wobble,allowing a high/low end at p.t.o. shaft /clutch joining.

[Dale Finch]

Try this...with engine NOT running, try to engage the PTO from the rear, and if it doesn't go in, try rotating the PTO shaft by hand, just enough to line up the splines from the 2 shafts, while pulling the PTO shift lever toward the rear. As Bob mentioned do this with the transmission fill plug removed (the large square plug just behind the gear shifter), so you can watch how it works.

[Glen]

Hi,
To engage the PTO, a shaft with splines, and a moveable clutch with splines have to be aligned.
Turning the clutch shaft is sometimes needed to align the splines. That means let the clutch pedal up, with the engine running, and then push the pedal down again, and try engaging the PTO.

If you can't get it to engage, people have said on here that if the PTO pilot bushing gets worn, they have had trouble engaging the PTO.
I think it is because the rotary mower belt pulls sideways on the PTO shaft, and makes the PTO pilot bushing slowly wear, whenever the PTO is off, and the tractor is being used.
The PTO ball bearing, at the rear of the PTO, being worn would let the front of the 11 1/2" long PTO shaft move to the side also.

Below is a listing at TM Tractor for a new PTO pilot bushing.

http://www.tmtractor.com/new/pt/752fp.htm

You have to remove the PTO assembly to replace the pilot bushing.
The Cub service manual has a section about the PTO.

[Spoonbow]

Thanks to all for the info and suggestions. Finally had a little time to look at the Cub today. Removed the filler plug and found that the set screw on the PTO clutch was loose and the clutch was sliding freely on the shaft. Tightened up the set screw, and now the shift lever won't move at all. Loosened the set screw again and reset it with the PTO clutch mid-stroke, still won't budge. Tried rotating the PTO shaft by hand (turns freely) but still unable to engage. Next steps, ideas, or diagnosis, anyone? Not sure I want to get into draining fluids and tearing down the PTO.
Thanks!
Matt

[Don McCombs]

The set screw is not supposed to be completely tight. Only tight enough to keep the clutch from slipping off the end of the shaft, over the small detent there. After you get the set screw where it needs to be, put a drop of green thread locker on the screw to keep it from backing out.

[Spoonbow]

I guess if I'd have thought it all the way through, I would have realized that it can't be tight. With that in mind, it seems like the clutch is unable to engage due to an alignment issue. Pilot bushing probably the most likely culprit, I'm guessing?

[Bob McCarty]

As mentioned earlier, did you check the pin that slides the clutch forward and back? It doesn't take much wear to keep the clutch from moving forward enough to engage the splines.

[Dale Finch]

In order for the clutch to couple the 2 shafts, the splines must be aligned. If your arm were about 2 feet longer, you could reach down and rotate the PTO shaft just enough for this alignment!!

Since that is not the case, my solution has been:
While attempting to engage the PTO, continue backward pressure on the shift lever and ever so slightly let up on the clutch pedal, JUST until the 2 shafts align and the shift lever clicks into place. Immediately press back down on the clutch pedal. Then proceed as usual.

Oops! Just was rereading this post, and realized I already posted this procedure! Didn't mean to be repetitive!

[Spoonbow]

As mentioned earlier, did you check the pin that slides the clutch forward and back? It doesn't take much wear to keep the clutch from moving forward enough to engage the splines.

I have not, as I ruled it out due to the fact that the shift lever is only able to move halfway through its throw. I figured a worn pin would permit full travel, but wouldn't actually move the clutch far enough forward to engage.

[Spoonbow]

Oops! Just was rereading this post, and realized I already posted this procedure! Didn't mean to be repetitive!

No worries. I've tried slowly rotating the PTO shaft by hand while attempting to engage the clutch with no luck. I'll fire the girl up this afternoon and try rotating the other end the arrangement.

[k hutchins]

I agree with Bob. I rebuilt a friends PTO a few years ago and ffound that the pin was worn more tha half way though. I replaced tha, but over the years of running it that way discovered that by not being fully engaged it had worn the splines on the inside of the PTO clutch. Tore it down again and replaced the clutch, voila it worked.
Unfortunately draining it and pulling it is about the only way to really check it at this point. If you use a clean bucket, and the trans oil is in good shape, you should be able to save it and reuse it.

Good luck BTDT

PS l'm sure you've already checked to make sure the pin is in the slot on the clutch, but sometimes we miss the obvious.