Aldeer.com Forums Alabama Deer Talk Aldeer General Forum Tractor PTO question

We broke the diverter input shaft on my batwing cutter. This cutter has smooth splines and uses shear bolts. I absolutely hate it. I found a new divider on Ebay for $700 but it is 20 spline. I was going to just replace the diverter and all 3 pto shafts to new shafts that have slip clutches to eliminate the shear bolts.

But the diverter company does not sell 6 spline units. Is there a way to do this? I am not sure why they wouldnt make a 6 spline for it, in my mind the 6 spline would be stronger than more smaller splines... Tractor is an old International 986 (about 100hp).

Any ideas, comments or suggestions?

6 spline is 540rpm and 20 is 1000rpm.

I would think more splines would be stronger because it would create more surface area. And I've only seen the 20 spline on big tractors over 100 hp.

Confirm 1 thing for me... is the broken input shaft 20 spline?

Are you saying that all you broke was the input shaft on the diverter box? If that is the case I would just fix the broken shaft and keep the original gear boxes if they are the originals.

But something doesn't seem right....almost like you are mix-matching 540/1000 drives on it. Typically if the cutter is 1000 PTO everything is 1000 on the drivelines on the same cutter. I have never seen one mixed up where it had 540 on some drive boxes and 20 spline 1000 on others. That's why they don't make it like that. These do not interchange.

Your 986 has what is called "small" 1000 and 540 PTO on the back of the tractor. Sounds like you have a 1000 PTO cutter which is stronger than 6 spline 540 PTO.

You can buy all the shafts off another small 1000 cutter if you can confirm they are long enough. The Rhino cutter I have is small 1000 and all the shafts have slip clutches. I think that is the way to go about this.

My tractor has both 6 spline 540 and a 20 spline 1000 rpm.

The shaft that broke is on the cutter. It is a smooth shaft with a shear bolt (that did not break). Cutter is not super heavy duty (Rhino flex s15). I hate the shear bolts. That is why I am considering replacing the existing diverter (that has smooth shafts) with the splined one, and replacing the shafts with a model that has a slip clutch on it. My unit does not have slip clutches, but each PTO shaft has shear bolts. I am hoping to do away with the bolts and have slip clutches. The new diverter has 20 splines.

I can replace everything and have the end of the new 20 spline shaft cut off and a 6 spline end welded on (for where it attaches to the tractor). I would prefer to attach it to the the 540 end on my tractor since that is what I have always used. Not sure the cutter could handle the 1000 rpm.

You know they make adapters right? I think Agri Supply had what I needed. I converted my shear bolt setup to a non-shear bolt and slip clutch to avoid the headache of frequent broken bolts.

That may be a solution to a problem you don’t have

Would there be a problem with replacing the shear bolts with grade 8 and adding the slip clutches? When I hit something the slip clutch would do its job. That would keep me from having to buy new shafts. What I really want is the slip clutches, those bolts are a pain in the rear. I can hit an ant hill and break the bolt.

That's exactly what I did. Add the Grade 8 (non-shear) bolts and let the slip clutch do its job.

I was breaking the grade 5's (or whatever grade I was using) just like you were.

I see what your problem is now... If the new gearbox = 20 spline = 1000 PTO. Won't work the gearing isn't right.

Sounds like all you need to do is repair the diverter box if you can get a replacement shaft then get a full set of slip clutch to Shearpin adapters for the PTO shafts.

Do the final drive shafts also have the same shaft/shear pin setup?

What you have going on sounds like a PITA. I also hate a shear pin.


If you look on German Bliss who carries Rhino parts you can probably find the replacement shaft you need but goes by the Serial #.

I am looking for the adapter to go from a smooth shaft to a splined shaft but dont see any. Looked on rural king, TSC, agris supply and amazon.

Anyone got a source (link)?

If I replace the smooth diverter gearbox with the 20 spline but run it off my 540 on my tractor how would gearing not be right? Do you mean the gears in the gearboxes at the end of the pto shafts (the ones over the blades)?

The shaft to replace what is in my existing tractor is $611 but I can replace the entire gearbox (with the 20 spline unit) for the same price. Would I be messing up by doing that and better off just repairing the existing diverter?

https://www.gaequipment.com/Slip_Clutch_Pack_p/sc-sp-sp.htm

Use a grade 8 bolt with this and your existing 20 spline PTO shaft.

Thank you

I am assuming your cutter is a 540 PTO cutter.

The issue is that if you buy an off the shelf replacement gearbox with 20 spline shafts... this 20 spline box will be geared for 1000 PTO. The gearing within the box will be different from the cutter's original gearing and that's going to change your blade tip speed.

If you can somehow confirm that the gearing is the same as your existing gearbox then it will work. I don't think that is going to be the case. This is why I said you need to replace the broken shaft and not the entire box itself. $611 is high as crap. Ouch.

I am surprised you can't get a NEW 540 diverter gearbox and then you'd be ok. They obviously made those cutters in 540 that's what you have. Call that German Bliss place if you want I deal with them and they will actually help you. They know more about Bush Hog parts than Bush Hog itself knows about their own equipment not kidding. You just need the serial number off the cutter.

If this issue comes up for you, it's possible to operate a 1000 pto cutter with using a 540 pto driveline. I t won't turn up enough rpms' to hurt anything. But you would never want to hook up a 1000 pto to a 540. you would nearly double the speed of the 540 output shaft. Most rotary cutters are turning at operating speed of between 14000 to 16000 feet per minute, regardless of whether 540 or 1000 rpm..The difference is that the 1000 rpm tractor shaft will be turning at nearly twice the speed to provide the same blade tip speed. The higher speed 1000 rpm is designed to reduce the torque load, which can shear away both internal tractor shafts as well as main drive-lines. The 1000 rpm rotary cutter is much heavier duty. If you already know this stuff, more power to you. But there's lots of folks out there that just don't get it. The difference between 1000 & 540 farm implements is the same as comparing a 1/2 ton truck axle to a 1 ton truck axle- it's just lower gearing. The drive shaft on a half ton pickup will turn fewer revolutions to move 10 feet than a 1 ton truck will. It's also why you'll notice the much bigger diameter of a 1/2 trucks' driveshaft (usually) as compared to a 1ton trucks' drive shaft. Less torque is involved to turn the 1 ton, so the shaft diameter can be smaller without the shearing risk. So its the same principle with farm driveline implements. Hope this helps somebody to understand the 1000/540 confusion stuff.

Thanks for the replies.

I’m going to just replace the shaft in my gearbox. And I’ll add the above posted slip clutches and replace my shear bolts with grade 8

Hopefully that will fix everything.