I think i broke my tractor

[Short Game]

Bad things happen when bolts are loose. I was thinking that a sticky thread for our LS forum would be good. One with charts of each LS series of tractors showing the bolts on each that need checking and the torques recommended for each.

I am pushing 600 hours on my R4010 (pre-4041) with no loosening issues I know of as yet. I use my loader with my 79 inch wide log forks that carry some heavy loads over bumpy ground, often very slowly. I can say I know I stress my loaders with lateral swaying, and so, keep a pretty close eye on those loader bolts. So far, no sign of loosening here.

The initial cause of the demise of my first tractor was frame to engine block bolts loosening. That loader was braced to the front of the forward frame, as used to be the norm. Someone has since figured out to brace them to the rear axle housings. So, it was probably loader mount stresses that caused that catastrophic failure.

 

[GManBart]

,,,Yes, there is some stretch, and it will always appear moreso if conditional issues are not fully factored in - or out where applicable. What I see is a dealer stating that there is a problem with "these" bolts coming loose. Im interpreting that as repetitively. The stretch from there to design issue is not so much.

That could be, or it could just be that the dealer is saying that loader attachment bolts need to be checked, because they are more likely to loosen than other bolts. That would make sense because they're stressed very differently than most other bolts on a tractor.

It sounds like you're saying the loader attachment bolts on your Kubota, or Mahindra were loose at one point? That tells me that it's either a common issue, and it's either unavoidable, or everybody else is getting it wrong as well.

I've seen the topic come up before, and folks seem to be reporting the same thing...some of the FEL attachment mounting bolts were somewhat loose at the initial inspection, and have stayed tight after being properly torqued. If it was truly a design flaw, they'd loosen up a lot more regularly.

It certainly could be that a higher grade bolt wouldn't stretch, and would make this a moot point, but that's not always a perfect solution either, because there's a tradeoff between hardness, ductility, durability, etc...there might not be a perfect solution here, and it's really not that big a deal to take 2min to check/tighten those bolts at normal service intervals.

In fact, all of the folks I recall reporting damage said they didn't know to check these bolts, or failed to do so....that's a pretty strong sign in my book. R,

 

[Jhiphop72]

Yes. I recall that ... a little. Checking thread engagement would probably have been part of formulating a solution to a problem that was being experienced. In the case of FEL fastenings I would feel insecure at only 1 dia thread engagement. Its a highly stressed situation employing hi strength bolts at their spec limit into castings that have variable pedigree and hole preparation. Top that with the tendency for the loader to be delivered and used loose and youve got some seesaw damage in the region of thread entrance before they are ever tightened appropriately. I am fortunate that the casting in the 7520 offers deep threaded holes -- I definitely used mine loose for several hrs immediately after delivery.
,,,Yes, there is some stretch, and it will always appear moreso if conditional issues are not fully factored in - or out where applicable. What I see is a dealer stating that there is a problem with "these" bolts coming loose. Im interpreting that as repetitively. The stretch from there to design issue is not so much. If it is a design issue it may be possible to accomodate it by tightening to the full spec of existing bolts or use of stronger bolts, hi strength washers to increase/spread the clamped area, and more torque. Essentially, a way around the design issue. Addressing by design would more appropriately involve a modification of various highly stressed joints to increase their stance - another bolt, slightly greater spacing. ... Hopefully the former workaround will be effective to fully stabilize the joints.

,,,Similar from another thread:

Sounds like your the right guy to build a better mousetrap, errr loader.. One that never needs checking. Why take away from good quality seat time by checking bolts?

 

[aginn]

If there is any damage at all to the threads, a helicoil kit is the only way to go. I have had bolts on a Cat that refused to stay tightened no matter whether locktite was used or not. After redoing the threads with the helicoils, I never again had an issue with them. Never even used locktite on the helicoiled holes. Good stuff and it is a lifetime fix.

 

[SPYDERLK]

That could be, or it could just be that the dealer is saying that loader attachment bolts need to be checked, because they are more likely to loosen than other bolts. That would make sense because they're stressed very differently than most other bolts on a tractor.

It sounds like you're saying the loader attachment bolts on your Kubota, or Mahindra were loose at one point? That tells me that it's either a common issue, and it's either unavoidable, or everybody else is getting it wrong as well.

I've seen the topic come up before, and folks seem to be reporting the same thing...some of the FEL attachment mounting bolts were somewhat loose at the initial inspection, and have stayed tight after being properly torqued. If it was truly a design flaw, they'd loosen up a lot more regularly.

It certainly could be that a higher grade bolt wouldn't stretch, and would make this a moot point, but that's not always a perfect solution either, because there's a tradeoff between hardness, ductility, durability, etc...there might not be a perfect solution here, and it's really not that big a deal to take 2min to check/tighten those bolts at normal service intervals.

In fact, all of the folks I recall reporting damage said they didn't know to check these bolts, or failed to do so....that's a pretty strong sign in my book. R,

The loader on my Mahindra was delivered "loose". I know this because I checked them within the first hrs of loader use. Once tightened the bolts have stayed tight thru very hard use, now at 1200hrs. People trusting the dealer or mfg to provide accessory implements properly installed seems to cause them trouble. Not only fasteners but hydraulics are problematic on new machines. If you think you should finish building a professionaly set up machine youve bought thats fine. For them to make it your responsibility is an abuse of all those not equipped to deal with it.

,,,I agree that it is not a big deal to check bolts. However; 1] It is a big deal to find them loose, and 2] Is a huge deal to find them loose again and again. If the second is happening something has to change because the fastened joint is being allowed to move to cause them to loosen. The joint [bolts, threads, clamped parts] is wearing - deformation of joint surfaces - danger of cracks forming, etc. The reason must be found and fixed. Either you or a professional has to do it. Then you can leave it and go to some other problem that isnt fixed or a modification youre making. ... I just try to limit the requirements dragged along behind. Theyre sneaky.
larry

 

[SPYDERLK]

If there is any damage at all to the threads, a helicoil kit is the only way to go. I have had bolts on a Cat that refused to stay tightened no matter whether locktite was used or not. After redoing the threads with the helicoils, I never again had an issue with them. Never even used locktite on the helicoiled holes. Good stuff and it is a lifetime fix.

Did you really use helicoils, or was it "case serts"? Helicoils require less to be drilled out, but in comparison form a less rigid thread that flexes more under load and is not as tolerant of assembly and disassembly [read careful and clean]. Were these small bolts, or structural?
larry

 

[ozley]

Even the orange one's have trouble

http://www.tractorbynet.com/forums/showthread.php?t=283270

 

[platinumaa]

The reason the mechanic gave me is "loose bolts".. he said it is somewhat common and he comes across it more often than people think.. he said no machine/tractor company is exempt.. it happens to all machines.. if they have bolts and have the ability to be screwed on than theres a possibility of them coming loose..

im new to the tractor world and have learned a valuable lesson.. i guess its similiar to what i tell my kids all the time.. "if its mechanical, its eventually going to break "

 

[k0ua]

"If it has teats or wheels, you're going to have trouble with it"

 

[Turbys_1700]

I just went through re-torquing the bolts on my Stoll aftermarket loader...
My loader has 15/16 bolts with 4 on each side of the frame...
I usually check mine once a year at the beginning of mowing season and I always have the top bolts needing a little snugging...
For some reason the bottom ones stay tighter...
I do not do a lot of heavy work with my loader and do not abuse it in anyway but I can tell you for a fact that those bolts do work loose and need checking...