Major structural failure on L4610 - ouch !!

_RaT_ · Jun 10, 2004

Thanks Dick, it's been interesting to speculate. You could be right, the failure process may have already started which would normally be apparent by looking at a discoloration on the casting caused by oxidation.

Henro · Jun 10, 2004

This description of things leads me to think the skidding load finished it off but something else had cracked it earlier ? 

If so, careful inspection of the cracked pieces may show something. An older crack may have a different color or something about it that causes it to look old. Some rust maybe? Or?

If everthing in the fracture zone looks identical, then chances are it was intact until it was stressed to the point of failure...

I don't have much experience in this area but do remember looking at failed parts when working and often there was a tell-tale difference, that indicated gradual failure,that was fairly obvious once you saw it...

_RaT_ · Jun 10, 2004

Bill either great minds think alike or small brains think alike, which ever the case, we thought similar. /forums/images/graemlins/wink.gif

Henro · Jun 10, 2004

And prooved that your fingers are faster than my fingers to boot! /forums/images/graemlins/smile.gif

rbargeron · Jun 10, 2004

The subframe is steel and would be much more ductile than the iron housings. I'm wondering if maybe there was an event that distorted the subframe - so it was already stressing the iron housing, even at rest - and the additional working loads put the stress levels over the top. To the naked eye the broken iron surfaces have a classic brittle-fracture appearance - very granular, no ductile flow, very low reflected light, no visible evidence of pre-existing cracks.

TresCrows · Jun 10, 2004

( If your going to do it, do it right! /forums/images/graemlins/blush.gif

I wonder what types of stress are put on a machine when using a three point winch that may not have been engineered for in the design of the tractor.

Keep us up to date on this please.

Dane )

Essentially if a machine is designed to handle a certain type of loads and a certain level of force and then more than that force is applied in a manner that it was not intended for by a device capable of generating more force than the machine was designed to handle then a major structural failure can be expected. /forums/images/graemlins/shocked.gif. A chain is only as strong as the weakest link like my buddy with the F150 who mounted a winch sufficient to pull an 18 wheeler and then tied the truck off when winching one day and to his surprise found his truck became somewhat deformed /forums/images/graemlins/shocked.gif. Hmmmm, maybe bigger is not better, maybe sizing to match is a better idea--nah /forums/images/graemlins/crazy.gif.
J

grandad · Jun 10, 2004

Trying to spot the bent/cracked subframe weld in the first pic. Are you are referring to the Kubota gray piece with the single bolt hole just left of the gaping hole? If so, that piece is a brace for the ROPS, which is also Kub gray, not the BH subframe. The actual BH subframe is the Kub orange structure beneath it in the picture.

I am going to have to check my rig this weekend (also 4610 with the same BH), but believe the only place the BH subframe actually contacts the rear end/3pt assembly is through a pair of U bolts that sandwich left and right axle housings between the ROPS on the top and the BH subframe on the bottom. You can just see part of one U bolt in each of the first two pictures, extending from where the grey ROPS assembly terminates above each axle housing. So a "bent subframe" doesn't ring true to me. Bent ROPS, maybe, but not the BH. Ask him if the ROPS ever really REALLY bashed into some immovable object or had some other kind of stress.

rbargeron · Jun 11, 2004

Grandad - You are completely right - I thought the gray piece across the back of the gearcase was part of the subframe - but it is really a part of the ROPS. Thanks for straightening this out. You are right that the BH subframe attaches elsewhere. I should not have been so quick to implicate the BH in this /forums/images/graemlins/blush.gif I may see the owner again this weekend - maybe I can ask him if the ROPS ever took a major shot. If I understand correctly, when the tractor is right side up the ROPS would actually reinforce the gearcase - but if the ROPS hits something the gearcase takes part of the load. The short gray frame piece in the picture is bent in toward the gaping hole. The crack is on the top out of view - open 1/4" at the far end.

rbargeron · Jun 12, 2004

I have the same concerns - about enthusiastic tractor operation that can lead to destruction. I don't encourage my teenage son to use my L5450 without my close supervision - which he'd rather not have I'm sure.

One thing I've noticed about my own winch (a Farmi 601) is that with the 3-ph raised, the top link makes a pretty steep angle - I can see how the forces could multiply pulling a load from the top pulley - especially with the hydraulic ram pressurized too.

On the other hand I've heard war stories about an older Ford tractor being literally lifted off the ground whole by it's winch, stalling the engine, but doing no damage.

Modern tractor design is a careful cost/performance balance. I still think anybody designing tractors should keep in mind that iron is relatively inexpensive and the tractor should have plenty of it - because the actual loads will occasionally be enormous. Tractors were made heavy in the past - perhaps for good reason. My 2 cents

kubmech · Jun 12, 2004

Anybody remember this discussion? web page Even though you have a subframe backhoe you still have to be careful of the load you put on that top link........ What happened to the bolts that secured the support brackets? Also somewhat related