Shear bolt my rear

[chas0218]

I bought a used 5' howse rotary mower. It had a shear pin style pto. Well the previous owner broke the pto guessing either hit something or the shaft wasn't working right. Whatever the issue he snapped it.

This is where my problems started. I removed the shear pin and tried to slide the shaft off, yeah right this probably has 15 years of rust keeping this thing on. So my endeavor started with trying to remove the completely shot universal joint. I managed to get 1 snap ring out and pound the universal from one side allowing me to get the angle of the dangle and slide it out.

Well now that I got the universal apart time to get that yoke off. Grabbed my 2 jaw puller and and got to work. Holy crap 2 hours later heating, spraying, tapping, heating some more, etc. I got it to move then another 30 minutes of tightening and tapping got her off.

I now have a bolt on slip clutch and pto shaft ordered. No more of this, I'll still take the pto off yearly and grease the shaft but I'm not going to rely on the shear pin to work when or if it gets rusted on.

 

[PCABE5]

What bolt on slip clutch did you end up with?

 

[Avenger]

As I was reading your post, I was thinking to myself "he needs a new shaft with a slip clutch." Only so much heartache before I scrap it and go get another, especially with something like a shaft. :thumbsup:

 

[chas0218]

What bolt on slip clutch did you end up with?

Below is the one I ordered. I'm betting I will need to trim it to fit but that isn't a big deal. Says it is for a Howse 5' or 6' so we will see. It is a bolt on slip clutch with shaft all in 1 unit.

HOWSE PTO SHAFT SHEARPIN SLIP CLUTCH FOR MOST ALL 5 & 6 ROTARY CUTTERS | eBay

 

[PCABE5]

Pretty good price for a clutch and shaft. Thanks for the info.

 

[chas0218]

Anyone know what the minimum clearance would be from bottoming out a pto shaft should be?

The closest it gets is about 3" from bottoming out. I was thinking the more overlap the better.

 

[LS Tractor Owner]

I just cut a new shaft that came with a new mower, I left exactly 3 inches of room before bottoming out. That is the minimum at full drop, it gets to about 2 inches when the shaft is perfectly horizontal, then goes back to 3 inches when the mower is fully lifted. I agree that the most overlap is better.

 

[ruffdog]

A frozen clutch is just like a rusted up shear pin connection. Both need service every spring to ensure they will work as they should.

 

[ovrszd]

A frozen clutch is just like a rusted up shear pin connection. Both need service every spring to ensure they will work as they should.

Yep. The clutch actually requires more maintenance. Especially if the cutter sits outside.

And in the end, in this case, still relying on a shear bolt.

 

[PCABE5]

Anyone know what the minimum clearance would be from bottoming out a pto shaft should be?

The closest it gets is about 3" from bottoming out. I was thinking the more overlap the better.

If I look through my Bush Hog manual they say that if it gets less than 2" you should shorten the shaft. So if you are at 3" you should be fine.

 

[ruffdog]

Yep. The clutch actually requires more maintenance. Especially if the cutter sits outside.

And in the end, in this case, still relying on a shear bolt.

On new equipment, I always take the time to grease the shaft/yoke connection where the shear bolt is. I use a marine grease that will last a very long time.

 

[chas0218]

If I look through my Bush Hog manual they say that if it gets less than 2" you should shorten the shaft. So if you are at 3" you should be fine.

Sounds good thanks!

 

[CobyRupert]

I believe for most PTO attachment configurations the shortest the PTO shaft needs to be is when the shaft is horizontal, and raising or lowering the attachment causes the shaft to telescope longer.
I want enough extra "slack" travel at this shortest position to be able to disconnect and pull back the attachment's PTO shaft from the tractor's PTO shaft.
:2cents:

 

[Avenger]

Exactly. Take a measurement when the implement is level with the PTO shaft from your tractor (with the shaft removed from the tractor and implement). That is the closest the two points will be, the shaft from the gear box and the PTO on the tractor.

An easy way to do this is to remove the plastic housing from the PTO shaft and measure it completely closed, telescoped all the way in. If that length is too long from your previous measurement, then you will need to trim, from both parts of the shaft, equal amounts. Measure again. (always measure again! Measure, go have a cup of coffee, come back and measure again.)

Now measure the shaft with about 3 inches of overlap. Extend the shaft. I wouldn't go less than that. Some manuals say 2in, whatever, but I prefer 3".

Measure the distance between the gear box shaft on the implement to the PTO on the tractor when the implement is at its highest, and lowest points. Remember that the implement will likely go further down than on level ground, find a hill or jack the rear of the tractor to get the 3pt all the way down. Those two distances should not exceed the length of your trimmed PTO shaft. If it does, then you either took too much off or your PTO shaft, or is completely wrong. Ether way, you will need a new one.

It also should be noted that most new shafts go together one way. The metal is extruded like a key. However, if your shaft is older and can go back together differently (like an old square shaft) then make sure you mark the yokes so they go back together the same way. They should be offset if memory serves.

Remember to reinstall the plastic on the shaft and your done, simple.

 

[PCABE5]

I believe for most PTO attachment configurations the shortest the PTO shaft needs to be is when the shaft is horizontal, and raising or lowering the attachment causes the shaft to telescope longer.
I want enough extra "slack" travel at this shortest position to be able to disconnect and pull back the attachment's PTO shaft from the tractor's PTO shaft.
:2cents:

Good point. I like how you stated "most" because I had an 2 older John Deere tractors that the shortest position was in the raised position. All about the geometry of the 3 pt.

If I could add to your thoughts, and that is with rear mowers, brush and finish, some have a flex hitch setup and the shaft has to accommodate that movement.

Now measure the shaft with about 3 inches of overlap. Extend the shaft. I wouldn't go less than that. Some manuals say 2in, whatever, but I prefer 3"..

Why does this seem to be a confusing statement?

3 inches of overlap would be awful short. Did you mean 3 inches on each side, total of 6 inches of overlap?

Most OEM's that I have knowledge of seem to have a minimum range of 7-9 inches of overlap. Always variables in every application.

 

[ovrszd]

Good point. I like how you stated "most" because I had an 2 older John Deere tractors that the shortest position was in the raised position. All about the geometry of the 3 pt.

If I could add to your thoughts, and that is with rear mowers, brush and finish, some have a flex hitch setup and the shaft has to accommodate that movement.



Why does this seem to be a confusing statement?

3 inches of overlap would be awful short. Did you mean 3 inches on each side, total of 6 inches of overlap?

Most OEM's that I have knowledge of seem to have a minimum range of 7-9 inches of overlap. Always variables in every application.

They mean 3" from bottoming out. The overlap distance would depend on total shaft length.

 

[PCABE5]

They mean 3" from bottoming out. The overlap distance would depend on total shaft length.

Right but my point is overlap and bottoming out are two different things.

 

[ovrszd]

Right but my point is overlap and bottoming out are two different things.

Yep. They are two different things. That's why you got confused when they started talking about 3". They were talking about bottoming out distance. You derailed and started thinking about overlap. They aren't talking about that at all.

Some PTO shafts have the square shape which engages all the way from completely apart to completely together. Most simply have a 6-8" square internal coupler welded onto a round pipe. They only contact at that coupler.

That type is why it's important to have some overlap because the only place it's applying driving force is within that coupler.

So far at least, this discussion has been about collapsing overlap, not extended overlap.

 

[chas0218]

My shaft is that triangle shape from yoke to the end so I'm pretty sure it contacts all the way.

What is the best to use to keep the 2 pieces free? I figure a moly grease would work best.

 

[ruffdog]

My shaft is that triangle shape from yoke to the end so I'm pretty sure it contacts all the way.

What is the best to use to keep the 2 pieces free? I figure a moly grease would work best.

When I get new/used equipment with a pto shaft, I'll separate the 2 halves, clean them and grease them by hand. That way I know the entire surface of the shaft is well lubed. I use a waterproof marine grease for items that might rust together.