I keep breaking bucket pivot pin

[arathkopf]

I have a 2017 KX040-4. I bought it used in 2021 and since have broken 3 bucket Pivot pins. I use it primarily for logging. The research I have done says the pins that have the grease zerk are bad because they break at the hole for the grease to come out in the center of the rod. So I got a solid pin that has no grease zerk. The arm has a grease fitting for me to get grease into where ther pin sits.

Any thoughts on why I keep breaking these ?

Also when I replace it I struggle to get the new pin in. I leave one of the broken halves in for alignment purposes then tap in the new one hoping it will slowly replace the broken one and everything will align, however once the new pin hits the old pin it shoots out and is a real PIA to get it all aligned to get the new pin in.

I welcome all thoughts as this is a real PIA for me.

 

[mikester]

If this is the 3rd time I'd start to ask what the operator is doing to break it

First time is bad luck. Second makes me wonder. Third sounds like an operator issue. It takes a lot of effort to break these pins.

 

[jimh406]

Doing a search it seems you have a miniexcavator. This forum is a tractor forum.

My only guess is the load you are putting on on the pin is more than it is designed for. I assume looking at where the break is could give you more of a hint on why. It could be the bucket you are using is giving the lift arm too much leverage. A more narrow bucket would change the leverage, but I have no idea if that will eliminate the issue.

 

[mcfarmall]

Doing a search it seems you have a miniexcavator. This forum is a tractor forum.

Make sure you tell the guys with track loaders and lawnmowers to take their questions elsewhere too!

 

[Yooper]

Any chance you could post a picture? I assume you are using the bucket and thumb to pick up logs?

 

[jimh406]

Make sure you tell the guys with track loaders and lawnmowers to take their questions elsewhere too!

Of course, I didn't tell anyone to go anywhere. From a practical matter, they might get better help if they go to a forum that isn't called tractor talks. I'm assuming there is a forum somewhere that has more excavator knowledge. Maybe I'm wrong.

 

[allis15]

I have a 2017 KX040-4. I bought it used in 2021 and since have broken 3 bucket Pivot pins. I use it primarily for logging. The research I have done says the pins that have the grease zerk are bad because they break at the hole for the grease to come out in the center of the rod. So I got a solid pin that has no grease zerk. The arm has a grease fitting for me to get grease into where ther pin sits.

Any thoughts on why I keep breaking these ?

Also when I replace it I struggle to get the new pin in. I leave one of the broken halves in for alignment purposes then tap in the new one hoping it will slowly replace the broken one and everything will align, however once the new pin hits the old pin it shoots out and is a real PIA to get it all aligned to get the new pin in.

I welcome all thoughts as this is a real PIA for me.

I would check the Hydraulic Pressure going to the cylinder. A previous owner may have increased the Pump Pressure beyond the Pins capability.

Also see if you can determine if the Cylinder has been replaced.

It too may have been replaced with a bigger one.

 

[Henro]

I would check the Hydraulic Pressure going to the cylinder. A previous owner may have increased the Pump Pressure beyond the Pins capability.

Also see if you can determine if the Cylinder has been replaced.

It too may have been replaced with a bigger one.

Along with Allis15’s suggestions, is there a chance that you are applying hydraulic pressure from the thumb cylinder and the bucket cylinder at the same time? If so, perhaps the pin is being subjected to forces that exceed the design limits.

Just something else you might consider.

 

[Henro]

Here is a good site you could get good advice from also:

Heavy Equipment Forums

Heavy Equipment Forums

www.heavyequipmentforums.com

It‘s the OTT for things like excavators and so on…

 

[dirtydeed]

Are you referring to the bucket pin on a mechanical quick change coupler?

Have you been replacing the pins with Kubota pins or sourced elsewhere? The factory pins are quite expensive but they are hardened. An off the shelf pin from tractor supply simply wont do.

If you have a thumb, the relief pressure on the thumb should be significantly lower than that of the bucket cylinder. I would suggest researching the thumb circuit relief pressure testing.

What I don't understand is why you need to leave half of the old pin in the hole in order to line up the new pin/bucket? Is there a chance that it has been line bored before?

 

[fried1765]

Doing a search it seems you have a miniexcavator. This forum is a tractor forum.

My only guess is the load you are putting on on the pin is more than it is designed for. I assume looking at where the break is could give you more of a hint on why. It could be the bucket you are using is giving the lift arm too much leverage. A more narrow bucket would change the leverage, but I have no idea if that will eliminate the issue.

My L48 TLB has the same Q/A as the Mini-Ex's.
I use Mini-Ex attachments.
Should I only ask questions about the basic L48 tractor here, but ask questions related to my Mini- Ex Q/A and attachments elsewhere?

 

[jimh406]

Should I only ask questions about the basic L48 tractor here, but ask questions related to my Mini- Ex Q/A and attachments elsewhere?

That's totally up to you. People ask questions about all kinds stuff here even though there are better places to get the information.

 

[Smokeydog]

Logging is tuff on any equipment. Picking up logs is a huge lever trying spread your bucket and thumb. If the pin didn’t break what is the next weakest link?$?$.
That pin might be the best insurance against breaking something more expensive. Good suggestion of checking pressures since used machine and people know it’s real easy to increase pressure. Worn bushing might allow more pin flexing fatigue.

 

[GreensvilleJay]

curious...
did all 3 pins break at the same place ??
a picture might help...

 

[ve9aa]

curious...
did all 3 pins break at the same place ??
a picture might help...

or....we all could just keep guessing blindly?

 

[woodman55]

How many hrs on the machine ? How many have you put on it ? three pins in two years is a lot. Are you handling logs, or digging rock with it ? How worn are the bushings ? Worn bushings will allow excessive movement, flexing the pin beyond normal tolerances.

 

[North Idaho Wolfman]

Lots of good points noted!
We need to know which pin or pins are getting broken!

 

[PoTreeBoy]

I'm going to guess you're using the bucket and thumb to handle long logs. If you don't have the load nearly balanced, the weight will cause a large twisting moment at the joint which it's not designed for.