More M59 repair fun.

[Gary Fowler]

I think that is the root of your problems, too wide a space on the boss connections which promotes more flexing of the pins. Not sure how easy that would be to narrow down the gap, perhaps just welding some spacer washers to the FEL "ears" might work.

 

[Billrog]

Having the cast piece narrower is actually a good thing when the loader arm can move back and forth a bit it has less of a tendency to wear a groove in the pin in 1 spot. You can stick a washer on each side of the arm and the grease will stay in much longer but you soon see the results of groves in the pin if you pull it and take a look.

 

[SPYDERLK]

What an interesting thread. I went out and took a look at my M59 this morning. I expected to see something like your speculations....something familiar to a US design mind. Something hopefully better made than an add-on Wood's loader because those are add-on's for farm tractors and this loader was deliberately designed as Kubota's entry into the the construction machine market. So they would be expected to assume that the loader would see somewhat higher stresses and lots more repetitions.

Looking at our M59, I can see that these upper loader arm pivots are NOT "welded on tubes"...nor is the piece a "blank cut on a horizontal bandaw". Arm pivots made like that would be appropriate for a lower stressed farm loader. But here we have a cast and machine-bored end piece that is welded (nicely) onto the end of the arm. It even has a boss especially cast as a place to drill and tap for a zerk. The problem - other than the unused zerk boss being in the wrong place - is that the cast piece is only 2.75" wide whereas the loader frame mounting space is 3.75" wide there. Why? The cast piece could easily have been wider....there's sure room for it. As it is, the cast pivot piece they've welded on is narrower than the arms themselves. All in all, that cast piece looks suspicioulsly like it was borrowed from a smaller loader - right down to the unused zerk boss.

Here's a couple of photos:

,,,,,Thank you for this homework! ... That zerk boss BTW is in exactly the wrong place ... aligned with the bow axis. The availability of an uninterrupted bearing surface there should not be foregone frivolously. Even a small change would be fully effective on that score -- and a greater shift would present the zerk for use on a solid pin.

I think that is the root of your problems, too wide a space on the boss connections which promotes more flexing of the pins. Not sure how easy that would be to narrow down the gap, perhaps just welding some spacer washers to the FEL "ears" might work.

Careful. ... Those ears are what amounts to sheet metal. Dont try to make them try support a twitch in the pin. Widen the already rigid pin boss out to the ears.

 

[Hersheyfarm]

What an interesting thread. I went out and took a look at my M59 this morning. I expected to see something like your speculations....something familiar to a US design mind. Something hopefully better made than an add-on Wood's loader because those are add-on's for farm tractors and this loader was deliberately designed as Kubota's entry into the the construction machine market. So they would be expected to assume that the loader would see somewhat higher stresses and lots more repetitions.

Looking at our M59, I can see that these upper loader arm pivots are NOT "welded on tubes"...nor is the piece a "blank cut on a horizontal bandaw". Arm pivots made like that would be appropriate for a lower stressed farm loader. But here we have a cast and machine-bored end piece that is welded (nicely) onto the end of the arm. It even has a boss especially cast as a place to drill and tap for a zerk. The problem - other than the unused zerk boss being in the wrong place - is that the cast piece is only 2.75" wide whereas the loader frame mounting space is 3.75" wide there. Why? The cast piece could easily have been wider....there's sure room for it. As it is, the cast pivot piece they've welded on is narrower than the arms themselves. All in all, that cast piece looks suspicioulsly like it was borrowed from a smaller loader - right down to the unused zerk boss.

Here's a couple of photos:

When you backdrag with loader in float over rough rocky ground you can watch the whole loader bounce back and forth inside its frame ears. To the point I stopped because the racket was too much. The cylinder ears have the same amount of play too.

 

[SPYDERLK]

Having the cast piece narrower is actually a good thing when the loader arm can move back and forth a bit it has less of a tendency to wear a groove in the pin in 1 spot. You can stick a washer on each side of the arm and the grease will stay in much longer but you soon see the results of groves in the pin if you pull it and take a look.

Until you consider the exposed areas as a grit magnet. :confused3:

 

[5030]

What an interesting thread. I went out and took a look at my M59 this morning. I expected to see something like your speculations....something familiar to a US design mind. Something hopefully better made than an add-on Wood's loader because those are add-on's for farm tractors and this loader was deliberately designed as Kubota's entry into the the construction machine market. So they would be expected to assume that the loader would see somewhat higher stresses and lots more repetitions.

Looking at our M59, I can see that these upper loader arm pivots are NOT "welded on tubes"...nor is the piece a "blank cut on a horizontal bandaw". Arm pivots made like that would be appropriate for a lower stressed farm loader. But here we have a cast and machine-bored end piece that is welded (nicely) onto the end of the arm. It even has a boss especially cast as a place to drill and tap for a zerk. The problem - other than the unused zerk boss being in the wrong place - is that the cast piece is only 2.75" wide whereas the loader frame mounting space is 3.75" wide there. Why? The cast piece could easily have been wider....there's sure room for it. As it is, the cast pivot piece they've welded on is narrower than the arms themselves. All in all, that cast piece looks suspicioulsly like it was borrowed from a smaller loader - right down to the unused zerk boss.

Here's a couple of photos:

I'd say eventually, you are screwed.

My La loaders on my M9 and 105X have way more rated lift than yours do btw. Pivot point lift is 3500 and 4000 respectively.

 

[SPYDERLK]

http://www.tractorbynet.com/forums/related-topics/232550-under-engineering.html

,,,,,,,,,,,,,,,,,,,,

 

[ultrarunner]

When I worked in the tool and machine shop I made pins and bushings for loaders used in a local foundry... they were moving sand all day and would get very worn.

I don't remember for certain... think I used 41XX steel for the pins?

 

[Billrog]

The first few backhoes I had approx. every 2 years I'd spend $ 2,800 on pins and bushings. The last hoe had 9,000 hrs. and the one I have now has 6,400 hrs. with original pins and bushings with no play. I made pins for all my buckets for the quick attach out of shafts from hydraulic cylinders. Cut them long enough so when I put a grove in them for snap rings the could slide back and forth 1/2".
Spiderlk my last comment on play was from experience not an opinion with a smaller case tractor with 4,400 hrs. used building skid trails and loading logs for 24 years.

 

[rScotty]

I'd say eventually, you are screwed.

Maybe so....maybe no. Stress risers and pin deflection are factors to know about, but not the only players in the material strength game. That's still a rather healthy pin, and I avoid shock loading the loader like I avoid doing that to anything. Working that way reduces the contribution of the stress riser toward a failure. There's a lot of M59s in use, and I'm not aware of other pin failures. But I may still pull mine and have a look. If I see a problem developing I'll just redesign the pin. It's a dandy tractor
enjoy! RScotty.