Adding zerk/grease fitting?

[rScotty]

That’s the “notch effect”. The radius is intended to reduce breaks but they still have created the weak spot.

Yes, the notch tells it where to break, but not why. Given a choice, having it break torsionally and perpendicular through the center of the pin is correct for both where and how the designer would want it to break....if it had to break. So he gets points for the notch. And extra points because the bottom of the notch is radiused instead of slotted with sharp edges. Having a radius dramatically reduces the main cause of crack propagation.

And since they seem to last 1000 hours, that says the pin is basically strong enough in shear and bending. But it should have lasted far longer than 1000 hrs. My guess is some sort of lube failure that affects one end of the pin more than the other. And maybe associated some way we don't yet understand with its having that bolted pin connection at one end.

After we see a few more pins that are worn but not broken we may get closer to the answer. In the meanwhile I'll be pulling those pins on mine for some maintenance. Might be a good thing to do at 500 hrs, too.

Which reminds me that we ought to look at a few new unused pins too. Just to see that they were made properly to start. They may have been designed properly throughout, and the problem could be nothing more than a production machine shop mistake.

rScotty

 

[jwmorris]

They may have been designed properly throughout, and the problem could be nothing more than a production machine shop mistake

It’s a different design than many king pins for sure but could even be a heat treat issue (if they even bother).

 

[Smokeydog]

The pin groove is for grease flow around the pin. Drilled hole longitudinally on one end for a zerk and then cross drilled to flow grease to the groove greatly diminishes cross sectional strength at center. I’m more in the shear stress flexing and fatigue failure at the grease groove camp. More flexing from wear over time. SWA-Guess.

Can’t remember if the bushing side had any grease grooves. Some bushings I have replaced also had a hole to align with the grease zerk on the cylinder cross tube or had to be drilled like what the OP was interested in doing. Be interesting if the L48 and M59 share the same pin at this attachment point?

The pins were only about $15 each back when I changed them. Probably stock for many loaders at that price point. Most loaders don’t have as high lifting capacity.

Hopefully a consistent lubrication regiment with high quality grease will extend joint life.

 

[Jason280]

Ok, finally had a chance to post a few pics.

Every pin that has broken has been in this exact same spot. Its important to note that not only is the crack in the middle of the "groove", but seems to originate/track from the grease port/hole that feeds grease out from the center (into the pivot).

If it breaks again, I will be converting over to the solid pin and adding an external grease fitting.

 

[Smokeydog]

Ok, finally had a chance to post a few pics.

Every pin that has broken has been in this exact same spot. Its important to note that not only is the crack in the middle of the "groove", but seems to originate/track from the grease port/hole that feeds grease out from the center (into the pivot).

If it breaks again, I will be converting over to the solid pin and adding an external grease fitting.

Good plan.

Your joints looked well greased.

I’ve gone from red grease, to 3% molybdenum (black) to Lucas HD green EP in search of better lube. Grease has gotten expensive and hard to get. Seen one tube of Lucas HD on eBay for about what I paid two years ago for a case.