Adding zerk/grease fitting?

[rScotty]

Oddly enough, I have three different Kubotas with FEL's, and it's the only one to ever break a pivot pin. That being said, my old '07 4330 (if I remember correctly, it's been replaced with a MX5400) and newer 7060 both have the external zerk fittings on the pins.

I don't see any reason why an zerk couldn't do its job just as well on the end of the pin as anywhere else. Having a single channel in the pin does put an extra requirement on what grease is used.

 

[jwmorris]

BTW, just to complicate a simple job, ZORO.COM has a great selection of zerks. I went crazy and bought this zerk thread gauge. Do yourself a favor and stick with something simple like NPT....

If it’s in a stressed area, I would probably go as small as I could. Maybe a 1/4-28. lots of fittings out there for that thread And if they do get broken off are generally much easier to remove than tapered pipe fittings.

 

[rScotty]

If it’s in a stressed area, I would probably go as small as I could. Maybe 1/4-28. lots of fittings out there for that thread And if they do get broken off are generally much easier to remove than tapered pipe fittings.

I sort of lean toward a 1/4" BSPT mysef - having always had a bias in favor of the British Standard threadforms for liquid sealing. That BSPT thread is so marvelously complex... and specifications call for it to be finished with a rounded top to the thread - a task guaranteed to win you friends at the machine shop.

I believe the swing arms on Royal Enfield Interceptors and Vincents both used that thread - as well as some older MGs, so they should be easy enough to find at any of those dealers.

Note that BSPT and BSPP (tapered and parallel) can be interchanged in some sexes but not others. *
Those tricky Brits were so way ahead of their time !!
rScotty

* Oh - just for simplicity, the rule is straightforward: a tapered male can fit a tapered or parallel female. That is, a BSPT (tapered) male thread can fit both a BSPT (tapered) and a BSPP (parallel) female since the taper of the male will fit equally into a cylindrical thread. Got that?

 

[mikester]

just a little aside.... are you using Kubota OEM pins or aftermarket?

i was told by my local parts supplier that their is so much junk / poor quality stuff flooding the market for some time which probably includes soft / weak pins. He says he regularly de-lists certain suppliers only to find the next in line banging on his door to buy parts flogs him the same inferior stuff. He called it a race to the bottom of quality. Price seems to drive a lot of buyers decisions. He claims it is getting very hard to find high quality / easy to find inexpensive sh@t.

Thats where Amazon and Flea-bay come to save the day

 

[Smokeydog]

The L48 was the first series of TLBs. Built tougher and higher capacities than its agricultural cousins. The B20 sold me on how useful a tank tough and versatile a dedicated tractor loader could be.

The SSQA lower pin broke on the M59 at the center grease groove of the pin. Those pins probably see more force, range of motion and dirtier environment of all the other loader pins. Grapples, my favorite attachment, probably increases the stress component. Pin wear causes flexing and eventually breakage. I could see and measure pin wear. Rather small diameter especially at the grease groove for a high capacity loader. Wether design flaw or design weak link feature to protect other more expensive components is debatable. Might step up the lube frequency and quality of the grease on just those pins if the problem persists.

One of the reason I installed a Kubota Soft Ride (KSR) system on the FEL. Reducing shock loading of components under load. Hope it gives the components as much comfort as the operator.

 

[rScotty]

If it breaks at the center groove, it almost has to be torsional rather than shearing stress.
For it to be flexural stress doing the breaking, it would have to have a LOT of slop.
Someday I'll get my KSR system set up, but I don't think that will have
an effect on the pins breaking.
Are the problem pins shown in any of those pictures?

 

[Smokeydog]

Part 190.

New
Companion
Broke

1080hrs questionable maintenance.
400hrs of heavy lifting since without problems.

 

[rScotty]

Part 190.

View attachment 787956
New
Companion
Broke

1080hrs questionable maintenance.
400hrs of heavy lifting since without problems.

Thanks for the photos. I think that puts it to rest. It looks like either design or maintenance rather than due to poor material.

Frankly, I don't like a pin design that constrains one side of a pin like that. It can lead to lube starvation and a torsional failure - as I believe it has here. Would regular maintenance have changed things? Reduced the wear? .... I just don't know. Regular maintenance with the wrong grease can cause similar problems too.

Bottom line is that particular pin design is a question mark in my mind. It's obvious what the designer was trying to do, and not all bad - but I'm just not completely comfortable with it.

I don't see it as a pending disaster - just a weakness - so I'm not inclined to drop everything & run out and make up different pins and lube channels. But now with 1100 hrs, what I am going to do is pull the pins on our M59 and inspect them.

I'll post to this thread when I do so. I always did want to grow up to be a tribology detective..

rScotty

 

[jwmorris]

Part 190.

View attachment 787956

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

 

[rScotty]

Part 190.

It looks like the associated bushing is part 020. Impossible to tell the length from the picture and the shop manual is no help. How did it look?