Bison Shenniu 25 PTO engagement? Will not go in smooth unless shut off. ??

[bob112]

I still cannot find a manual anywhere for this tractor so everything is a guess but I know the old fords and the PTO lever should engage with tractor running? As well, on our Fords, the PTO engages/disengages with the clutch and this is not working on the Bison? Is there an adjustment somewhere? When I try to engage, all I get is grinding. I am not sure of the internals of the Ford but it seems that the clutch lever also actuates the PTO clutch so when the PTO is engaged, so as you let off the clutch, the PTO would engage just before the tractor starts moving.

There is a max pedal throw adjuster but pretty much all the way down. I was hoping there was a simple adjuster somewhere but cannot find it. I shut the tractor down and it will engage just fine and run, just need to get engagement working right.

help?

 

[ovrszd]

There are a variety of PTO engagement types. The three most common are "non-live", "live", and "independent".

Non-live PTO only runs with the clutch engaged. It is directly driven by the transmission input shaft. No input shaft movement, no PTO. Very early Fords, 8N and such had this design. It was crude at best. Push in the clutch to stop tractor movement and the PTO attachment stops turning. Also, another bad side effect, if running a brush hog for example. The spinning PTO shaft will propel the tractor forward until it stops turning if used without an "overriding clutch" on the PTO shaft.

Live PTO is what I believe you are familiar with. With engine running, tractor sitting still, disengage clutch, engage PTO with small lever usually on side of transmission. Some grinding might be heard if you engage the PTO gear before the transmission parts stop spinning. Some older Fords used a 2 stage clutch to get the "live" part. Push the clutch pedal down 2/3 of the way and the tractor will stop moving but the PTO will continue. Push the clutch completely down and both stop.

Independent PTO is engaged by an oil clutch inside the rear housing. This PTO is most popular and can be activated/deactivated irregardless of tractor movement or clutch engagement/disengagement. Has not affect on tractor movement. No push. No stopping because of clutch disengagement.

On my Ford this is accomplished with a double splined clutch assembly and double shafts coming out of the transmission front. The inner shaft is the transmission input shaft and is driven by the clutch plate. Engage clutch tractor moves, disengage clutch tractor stops, all with no affect on PTO. The outer shaft is splined into the pressure plate and turns anytime the engine is turning. This drives a shaft thru the transmission to the rear axle assembly where the PTO oil clutch is located.

For your tractor to be making a gear grinding noise when you try to engage PTO it is at best a "live" setup and requires the clutch be disengaged and all gear movement stopped before it is engaged.

With that said, engine running, transmission in gear, clutch disengaged and tractor movement stopped, PTO should be able to be engaged with the lever with no grinding. If it can't, then we have a problem.

If the tractor clutch is wayyy out of adjustment I guess it would be possible that the transmission main shaft keeps turning with engine running, transmission in neutral, clutch disengaged. But if that were the case it should be hard to get the transmission in gear with engine running, grinding, etc?

 

[bob112]

You know, I do not think we have tried having her in gear! That might be the missing link here. I have been sitting on a tractor with separate PTO clutch too long. Been a long time since I needed PTO on a CUT tractor.

I know with the tractor out of gear and pushing the clutch, the PTO does not stop but of course I cannot test if it is just free wheeling without some injury.

 

[ovrszd]

Not knowing the condition of your clutch assembly, i.e., oil soaked, worn out, whatever, it may be that it will not disengage enough to stop the transmission input shaft without some load applied. That load could be putting the trans in gear before engaging PTO lever or if the PTO had a load on it such as an attached brush cutter.

EDIT: no way take ahold of the PTO shaft with it spinning. Probably wouldn't do more than skin the snot out of your hand. I'd be more concerned if you had a glove on and it got ahold of it....

 

[bob112]

I was totally kidding. I do a lot of educating on spinning shafts. Being around lathes, it is VERY scary. Farm boys get very injured not taking it seriously. I would say if I can get the lever to engage the PTO while running, we will say it is probably working fine. I know on my big tractor, when you first fire it, the wet clutch will drag and run the PTO if nothing is attached until it warms a bit. No biggy.

I cannot imagine this tractor having a full time PTO as it is dangerous. What mean there is once the lever is engaged, it would not stop unless the lever is disengaged. It only make sense when you stop the tractor that you want the PTO to stop, for safety.

I will test and report back.

 

[bob112]

Nope, that did nothing for it. I seriously cannot figure out how this thing works without some sort of diagram or something to know how the PTO might disengage with the clutch. I believe the whole hang up here is the clutch is not stopping something from spinning so it can engage. Not sure if there is an adjuster or not. My luck, prob not and the whole reason the tractor was sold to me as "nothing wrong".

 

[ovrszd]

I was totally kidding. I do a lot of educating on spinning shafts. Being around lathes, it is VERY scary. Farm boys get very injured not taking it seriously. I would say if I can get the lever to engage the PTO while running, we will say it is probably working fine. I know on my big tractor, when you first fire it, the wet clutch will drag and run the PTO if nothing is attached until it warms a bit. No biggy.

I cannot imagine this tractor having a full time PTO as it is dangerous. What mean there is once the lever is engaged, it would not stop unless the lever is disengaged. It only make sense when you stop the tractor that you want the PTO to stop, for safety.

I will test and report back.

Most modern PTO systems have a "light" brake system built into them. So, if the tractor engine is running and the PTO is disengaged, the shaft will not turn. Safety first. Shut off the engine and the PTO brake will release, allowing the operator to turn the shaft to align whatever attachment is being hooked to the tractor.

I don't know of any tractor that has a full time PTO. But I'm certainly not saying that is not possible. On my Ford or my Kubota, once you engage the PTO lever it will run without fail until the engine stops running.

I don't want my PTO to stop turning when the tractor stops moving. I only want it to stop turning when the engine stops turning. That's the difference between "non live" PTO and "independent PTO".

We'll figure it out. It's just more time consuming and difficult dealing with the communication media that we have here. No worries.

 

[ovrszd]

Nope, that did nothing for it. I seriously cannot figure out how this thing works without some sort of diagram or something to know how the PTO might disengage with the clutch. I believe the whole hang up here is the clutch is not stopping something from spinning so it can engage. Not sure if there is an adjuster or not. My luck, prob not and the whole reason the tractor was sold to me as "nothing wrong".

Hmmmmm. So we are saying that with the engine running, and transmission in whatever configuration, the PTO cannot be engaged without gearing grinding??

Again, due to our method of communication we need to clarify even the smallest detail.

 

[ovrszd]

Nope, that did nothing for it. I seriously cannot figure out how this thing works without some sort of diagram or something to know how the PTO might disengage with the clutch. I believe the whole hang up here is the clutch is not stopping something from spinning so it can engage. Not sure if there is an adjuster or not. My luck, prob not and the whole reason the tractor was sold to me as "nothing wrong".

Hmmmmm. So we are saying that with the engine running, and transmission in whatever configuration, the PTO cannot be engaged without gearing grinding??

Again, due to our method of communication we need to clarify even the smallest detail.

 

[bob112]

Hmmmmm. So we are saying that with the engine running, and transmission in whatever configuration, the PTO cannot be engaged without gearing grinding??

Again, due to our method of communication we need to clarify even the smallest detail.

That is a big 10-4. No configuration will allow the PTO lever to be engaged at all. Just feel it grind. Tried a little more pressure and just won't do it. I suspect if I tried stopping the PTO with the clutch in, it would not stop.

I am not even sure what sort of design I would be looking for here. Not sure what Fords used. clutch pack?