Colt Case Ingersoll Garden Tractors

Advice question: When I built my new front axle, I located the bell cranks, (aka the steering arms) up on top of the axle, on the upper side of the kingpin.

The hydraulic steering cylinder itself is attached to a steering arm down under the axle, at the bottom of the kingpin.

So, on the right side, the hydraulic steering cylinder moves the lower steering arm, and the righthand hub/spindle assembly with it.

When the righthand hub spindle pivots, the kingpin turns the right hand upper bell crank (steering arm), and that's attached to the tie rod, and the tie rod makes the lefthand bellcrank/steering arm move, so both steering spindles pivot together.

The upper bellcrank/steering arm is attached to the kingpin with a 1/4" roll pin.
Today the righthand roll pin apparently sheared off. Because the righthand spindle assembly and kingpin are moving, but the steering arm, and the whole lefthand spindle assembly are sitting still.

This makes it challenging to drive the tractor.



My engineering reference told me that that roll pin should have 4000 lbs of shear strength, which I thought would be more than plenty.

I apparently thought wrong.

The same part on whatever farm tractor has the steering arm attached/locked in place via a spline.

I presume I'm going to have to tear it apart and cut a spline on the kingpin and the inside bore of the upper steering arm.

That's going to be a REAL pain.

Any other ideas before I do all that work?

Bob

I was thinking a 6mm taper pin https://spaenaur.com/catalog/E92/ because they are rated at 72,000 psi but calculate back to a shear strength of 3,600 psi but 18-8 dowel pins https://spaenaur.com/catalog/E82/ might do the trick. I am spoiled because this company warehouse is 20 minutes from me and delivers for $5.00. McMaster Carr may have taper pins with better specifications. https://www.mcmaster.com/taper-pins/taper-pins-5/

A .250" grade 8 bolt would probably work better.

There shear strength on a 1/4" grade 8 calculates out to approximatly 7,500 lbs.

Spike188 wrote: ↑Mon Nov 21, 2022 7:47 pm There shear strength on a 1/4" grade 8 calculates out to approximatly 7,500 lbs.

Grade 8 bolt is what came to mind too. Be worth trying before taking it all apart. Or what about the possibility of opening the hole up and trying a grade 8 3/8-24 bolt? That would more than triple the shear strength of a 1/4 roll pin.

Are there grade 8 bolts smaller than 1/4” ? I have a place for that if there is such a thing. 3/16” is what I need.

Noel

Noel, a #10 grade 8 bolt is 3/16"

#10 bolts are theoretically 0.190" and 3/16 equals 0.187"

It needs to have zero play, not so much as a wiggle. The roll pin, being spring loaded eliminated play. And a tapered pin would do the same.

But using a bolt is going to be tough. I could precision turn the bolt and ream the hole, but even then I think I'd need to use Loctite to eliminate play.

And that would make disassembly a nightmare.

And I'm afraid to drill it much larger than 1/4", as I'm concerned it could begin to weaken the 1" kingpin itself.

The thought occured to me to install two roll pins at right angles to each other, vertically separated by... 1/2 inch? I don't know how much separation I'd need to maintain the kingpin's strength/integrity. But I'd probalby need to pull the current kingpin and weld closed the existing hole and redrill altogether, because the current hole is right in the center of the bellcrank collar.

Bob

How about a spirol pin? 1/4" OD and 7,800 Lbs.
https://www.zoro.com/zoro-select-spring ... TCEALw_wcB


Gordy

I have a different question for you guys: should there ever should be more than 4000 lbs force on that pin? Under normal circumstances the only force opposing the steering force is the front tires friction on the surface of the soil. I have serious doubts that opposing force is anywhere near 4000 lbs.

I'd double check the range of movement of the wheels against the full range of movement of the steering cylinder. Even a little discrepancy would cause that pin to sheer.

If that checks out my second theory is that the pin was maybe of lesser quality and nowhere near the 4000 lbs rating.

Spike188 wrote: ↑Mon Nov 21, 2022 8:20 pm Noel, a #10 grade 8 bolt is 3/16"

#10 bolts are theoretically 0.190" and 3/16 equals 0.187"

Thanks Spike.

Noel

@thebuildist I would start with replacing the pin and make sure all is still tight . Then find another smaller pin that will press in that new pin . I have seen this from factory on high shock load application . No one hit did this . It has been a many that add up do to the fact that it is hollow . adding a second pin in side of it reduces the deflection . I have seen spiral pin , cotter pins, and what looks like a old common nail pressed in and then peened or bent to keep in place. Spiral pins also work well , but must be clocked so the forces are not on the over lap .

Thanks everyone for your input. Based on all the ideas, it seems like I don't need to go nuclear and cut a spline into this thing.

It seems like either the coiled spring pin or Dave's idea of putting a pin inside a pin. What a neat idea. I never thought of that.

I did some measuring today. And it looks like I drilled it 9/32.

I know that I used a roll pin that I had on hand. So I'm wondering if I actually had an 8 mm roll pin on hand. Because a quarter inch roll pin is too small and a 5/16 roll pin should be too big.

And if I did pound a 5/16 roll pin down into that hole, then maybe I damaged it by curling it so tight.

I say all that to say that I'm going to drill it out to 5/16 and either put in a 5/16 coiled spring pin or a 5/16 pin with another pin inside of it the way Dave recommended.

I'm going to order them both and think about it while they're on the way.

But thanks again everyone.

Bob

I decided to go ahead with the 5/16 regular roll pin and put a 3/16 roll pin inside of that.

But before I did that I also realized that the outer collar that the roll pin is going through is a little thin. The kingpin is a 1-in rod and the collar going around the kingpin is only 5/16 of an inch thick.

And I think in retrospect that one of the things that happened is that 5/16 was applying a narrow pressure to the side walls of the roll pin and causing the flexing that ultimately led to failure.

So I decided to make that collar thicker. And to do that I bought a one and a half inch ID shaft collar from tractor supply and stuck it in the lathe and bored it out to a thousandth of an inch less than the OD of the current collar, and pressed it on.

Then I went ahead and welded the gap between the steering arm and the new outer collar. Lastly I drilled through both collars to 5/16 of an inch, and drilled out the kingpin to 5/16 of an inch. And drove in the 5/16 roll pin, followed by a 3/16 roll pin into the center of that.
Time will tell how it holds up. But I feel good about it.
Bob

Should be good to go now Bob @thebuildist

What tractor are you working on?

Seabee wrote: ↑Wed Nov 23, 2022 10:07 pm What tractor are you working on?

It's a highly customized Ingersoll 4020.

Custom heavy duty front axle, reinforced frame, removable loader.

Bob

https://m.youtube.com/playlist?list=PL1 ... TKYswXu40K

Thank You! I found the thread interesting, but couldn't figure out what tractor was getting the special treatment.

Bill