Removing PTO driveshaft from RC

[Pooh_Bear]

I have an old abused rotary cutter (brush hog).
I have no idea what brand it is. I has been painted all red.
I am wanting to remove the driveshaft from it and use it on something else.
Normally I would expect a shear pin holding onto the gear box.
But this has something like a set screw. But it is more like a 1/4 inch bolt with a square head on it. Or rather it had a square head on it. I took a wrench and tried to remove it and the head broke off. All that was left was the threaded shank sticking up.
Ok, so I found a nut that would screw onto what was left of the bolt.
Screwed it down even with the top of the bolt and welded it in place.

Ok, so how should I proceed from here.
I'm afraid if I just try to turn the nut, the bolt will snap off flush with the yoke.
I was thinking of heating the yoke to expand it, then remove the "bolt"

Isn't there a trick of some kind where you heat it and spray it with WD-40
and it wicks the oil down into the threads to help remove it.
Seems like I remember reading something about that here somewhere.

My RC hardly gets any use. And I need the drive shaft for something else.
When I put it back on the RC I will use a shear pin.

So how do I get this "bolt" out without doing any more damage.

Thanks.

Pooh Bear

 

[RonR]

For starters, dump the WD40 and buy a can of PB Blaster at your auto parts store. Spray the threads liberally over several days, if you can wait that long. Then I'd use a punch on the bolt and give it a real WHALLOP downward to try to break it loose.

You might end up breaking it off. If so, proceed with a drill bit and an easy out. Worst case, you drill the old bolt out completely and have to re-drill and tap a different spot.

My guess is that there is a keyway in the shaft, and the setscrew sits on top of the key to hold it all together.

Ron

 

[Pooh_Bear]

I don't think there is a key. Unless it is a woodruff key.
I can't see a keyway on the end of the shaft.
I'm thinking the end of the bolt goes into the hole where the sheer pin would go through.
The yoke is not tight on the shaft. It can wiggle a bit.
I can't understand why a RC wouldn't be using a shear pin.

Pooh Bear

 

[BTDT]

Is the end of the coupling open on the u-joint side? You might have to break apart at the u-joint and look up in there to see if coupling has key slot. What were you planning to use this shaft on? Does it have the same coupling/shaft diameter, splines, etc.

 

[Atlas]

I can't understand why a RC wouldn't be using a shear pin.

Pooh Bear

It doesn't sound like you are the original owner. Based on that theory, who knows what a previous owner did to it. Maybe they broke the shear pin and replaced it with a bolt.

 

[Pooh_Bear]

Nope, I'm not the original owner. It came with the tractor.
I don't even know what brand it is. Sure is heavy tho.

I can see the gearbox shaft. I'll look again for a keyway.
I don't remember seeing a keyway on it. Been a while since I looked.

What am I using it for:
I got one of them cheap little 1/2 HP clear water, water pumps from Harbor Freight.
The motor on this thing is severely underpowered. Gets real hot when running.
And where I want to pump water from is too far from the house to run electric.
I tried running the pump off an inverter hooked up to the tractor battery.
But I had to run the tractor (8N) at full throttle so the alternator could keep up.
I got to looking at the pump and motor, totally enclosed fan cooled motor.
So I removed the cover off the back of the motor, and removed the fan,
and replaced the fan with a lovejoy coupling.
I fabbed up a belt and pulley transmission to drive the pump motor at the correct RPM off the PTO of the tractor at idle speed. I just need the driveshaft to hook up the belt and pulley transmission to the PTO on the tractor.
Then the tractor can sit and idle while I pump all the water I want.

The electric motor is 2800 RPM.
Engine idle speed is 450 RPM making PTO idle speed 200 RPM.
200 RPM run thru a 1:14 step up transmission makes 2800 RPM.

Belt and pulley transmission is in two step ups.
12 inch pulley to 3 inch pulley, then 7 inch pulley to 2.5 inch pulley.

All I need now is that PTO shaft.

Pooh Bear

 

[Soundguy]

Hmm.. I'm thinking there must be a keyway, if this is a smooth shaft and yoke. Certaintly a 1/4" bolt would not be enough to hold a smooth shaft to a yoke, under heavy work load. I see 4' and 5' mowers pop 7/16 and 1/2 bolts all day... So.. perhaps check the rear of the yoke for a keyway slot.

If the yoke is loose on the shaft, and our guess is right about the 1/4" bolt being a keeper for the key.. you may be able to use a gear puller, and just pull the yoke off.. It's likely the stub of the 1/4 bolt holding the key will just shear and let you disassemble...

Soundguy

 

[Doc_Bob]

If you can, post some pictures. I suspect that that would help everyone come up with some better ideas.
Bob

 

[Soundguy]

Yep.. this is deffinately a place where a pic is worth a thousand words.. etc.

Soundguy

 

[Pooh_Bear]

It rained all day today. Supposed to be clear the rest of the week.
So maybe tomorrow I can take a look at it and get pictures.

I may have just missed the keyway. I haven't looked in a while.

The other holes (not tapped) in the yoke look like they take
a 7/16 bolt thru the whole yoke for a shear pin.
These holes are at a right angle to the threaded hole.

Pooh Bear

 

[Soundguy]

If it does indeed take a shear pin.. then there won't be a key way.

I wonder if there is a slot amchined around the shaft, and this 1/4" screw is used as a 'locater' in case the shear pin breaks.. so that the yoke doesn't fly of f the shaft? ( bad design if so.. however.. i've seen worse designs. .. most good designs use a circlip or e-ring in a groove near the end of the shaft to retain the yoke.. etc.. )

Soundguy

 

[Pooh_Bear]

I managed to get it off finally. Been working on it for 4 hours.

First, I took a propane torch and heated the yoke up real good,
then started twisting the nut I welded on. It broke off.

Next, I drilled down as deep as I could get with a small bit.
Then I drilled it out with a 1/4 inch bit. Still no go.

I figured there can't be much material left. Maybe I can shear it off.
So I took the tractor down by the river and found a small stump.
I backed over the stump and set it at full throttle.
Then I lowered the brush hog on the stump. Till the motor stopped.
Yeah, stupid thing to do. But I did it about 10 times.
That bolt refused to shear off. I gave up on that idea.

I took it back up to the shed, got a slightly bigger drill bit,
I sharpened it up real good and went at it. Used cutting oil this time.
This drilled out some more material. But it still wouldn't come off.

So I got the propane torch and heated it up again real hot.
Then I took a sledge hammer and beat the yoke off there
with just a few blows to it. It had a wooddruff (half moon) key in it.
The gearbox shaft had a keyway for a wooddruff key
so that is why I couldn't see it. But the yoke had a plain keyway in it.

When I put this all back together it is just getting a shear pin.

And I got pictures this time.

Thanks for the help.

Pooh Bear

 

[Soundguy]

I was figuring there must be a key in there.

Glad you finally got it off.

Soundguy

 

[Pooh_Bear]

I still don't understand why it was put together that way.
Absolutely no shear protection at all.

Glad I don't use this thing very often.

Pooh Bear

 

[Soundguy]

Perhaps an aluminum or brass key could have been used for shear protection??

Soundguy

 

[Donman]

Playing a lot of heat around the welded nut (not on it-might weaken the weld) so as to get it dull red, then take your wrench and wiggle back and forth might loosen it it enough to get it out. I've been amazed quite often what heat can do.

 

[BTDT]

I still don't understand why it was put together that way.
Absolutely no shear protection at all.

Glad I don't use this thing very often.

Pooh Bear

The woodruff key is the shear protection. That's the same setup as a magneto/flywheel on a small gasoline engine (Briggs & Stratton)

 

[Pooh_Bear]

Then why didn't it shear when I ran it up to full throttle
and dropped the brush hog on a stump. It sure stopped the engine.
I did this 8 to 10 times before I gave up. Hope I didn't damage the tractor.

When I was drilling out the bolt, when I got to the woodruff key,
I had to keep sharpening the drill bit. I think the key was hardened.
Otherwise I should have been able to drill thru it easier than the bolt.

Pooh Bear

 

[Atlas]

Not wanting to believe a company would design and market a brush hog without shear protection, I'd say a previous owner didn't care about or understand the concept.

 

[Willl]

The woodruff key is the shear protection. That's the same setup as a magneto/flywheel on a small gasoline engine (Briggs & Stratton)

While your correct that the briggs key (aluminum) is for shear protection, his steel woodruff key is not.
(note; do NOT use a steel key in place of the aluminum key on a briggs.)

Pooh, is it possible the shear protection or slip clutch was on the tractor end of that driveline ?