Kingpin to bell crank arm attachment
Posted: Mon Nov 21, 2022 6:37 pm
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
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