Kubota rear axles/differentials

/ Kubota rear axles/differentials #1  

om21braz

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Has anyone here ever had any problems with rear axles/diff. or the seals on the Kubota machines. I'm assuming most of you have not and I'm positive that Kubotas' engineers are far more educated than me - but I'd prefer seeing the diff. case/housing come out much closer to the hub end of the axle for more support. I'm sure it's went through numerous tests, etc. - but it just don't look right to this old dumb country boy.
Just to be clear, I'm not referring to the portion allowing for wheel spacing adjustment.
 
/ Kubota rear axles/differentials #2  
I had to have both rear seals (where the axles exit the transmission) replaced due to leakage. B2410 tractor is 2 years old and had around 85 hours on it. Repair was covered under warranty. Mechanic told me that he wasn't impressed with the design of the seals. He indicated that he would have liked to see a dust cover on top of the seals.

Hope this helps.
 
/ Kubota rear axles/differentials #3  
I think I may know what you are refering to - the fact that at the wheel centerline there isn't a shaft and housing that goes all the way from one side to the other - instead there are separate "gear reducers" for each rear wheel hub. My 1982 L345 DT was built like that - and the reducer housings were formed steel - not cast iron like the newer ones. But they held up just fine. Hope this is relevant to your question. Takle care, Dick B
 
/ Kubota rear axles/differentials
  • Thread Starter
#4  
</font><font color="blue" class="small">( I think I may know what you are refering to - the fact that at the wheel centerline there isn't a shaft and housing that goes all the way from one side to the other - instead there are separate "gear reducers" for each rear wheel hub. )</font>

You're close. The fact they are separate, that is understandable - but that the housing is'nt longer on each side exposing less of the actual axle and placing the bearing out further giving more support to the axle. I expect it is due to cost cutting - think about making the housing on each side a few inches shorter on thousands of tractors - adds up quickly. But as mentioned earlier, I would expect Kubota to have calculated the stress and determined it is enough support to do the job - maybe not overkill as things used to be built. Thanks for the replies !
 
/ Kubota rear axles/differentials #5  
In some cases this may be done because there are narrow and standard width versions of the same tractor.

I don't know, but perhaps when a narrow version is produced, they then only have to install shorter axles rather than produce two different housings...

My B2910 has about six or more inches of axle protruding beyond the axle housing...

There are also rear track assemblies that bold onto the rear axle housing in Japan that are used in place of rear wheels. Maybe this has something to do with the design also?

Attached is a photo of a small tractor with tracts installed (15 hp) but I have seen them on larger tractors as well...
 

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/ Kubota rear axles/differentials
  • Thread Starter
#6  
</font><font color="blue" class="small">(
There are also rear track assemblies that bold onto the rear axle housing in Japan that are used in place of rear wheels. Maybe this has something to do with the design also?)</font>

Henro, that may very well be why it's designed as it is and one less style of casing to stock - neat pic of the Bota' w/ tracks !
 
/ Kubota rear axles/differentials #7  
I believe you are creating an issue that does not exist. Most tractors I believe have exposed axles beyond the housing and whether they do or not really does not matter. On some Kubotas the wheels can move in and out on the axle shaft for different positions. If the housing went all the way out to the wheel this would not be possible. The axle is sized to carry the weight and loads imposed on it. If you bend one of these axles then in a similar situation you would have cracked a full length housing. J
 
/ Kubota rear axles/differentials #8  
With the idea that bending an axle would fracture an imaginary extension to the casing ... what do you experienced folks say about this situation? My 17hp Kubota managed to (over-)load it's 3 point system to such an extent that it now has a ruined [fractured in two] hydraulic cylinder case and a badly damaged top rear edge on the differential case; the edge damage is a consequence of the hydraulic cylinder case getting ripped off of the tractor.
Looking at the damage causes me to wish the tractor had been designed so that an (over-)load would break the lift arms rather than allowing them to transfer the (over-)load to their shaft which then fractured the hydraulic cylinder case.
 

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/ Kubota rear axles/differentials #9  
With the idea that bending an axle would fracture an imaginary extension to the casing ... what do you experienced folks say about this situation? My 17hp Kubota managed to (over-)load it's 3 point system to such an extent that it now has a ruined [fractured in two] hydraulic cylinder case and a badly damaged top rear edge on the differential case; the edge damage is a consequence of the hydraulic cylinder case getting ripped off of the tractor.
Looking at the damage causes me to wish the tractor had been designed so that an (over-)load would break the lift arms rather than allowing them to transfer the (over-)load to their shaft which then fractured the hydraulic cylinder case.

The tractor did not overload the 3-point, the operator did.
 
/ Kubota rear axles/differentials #10  
Were you using a logging winch or 3 point backhoe? Common damage from that type of use on compacts.

Re the axle length, my 5030 doesn't stick out far beyond the casting. Take a look at ag tractors with axle mounted duals, they have about 3 feet of axle sticking out beyond the casting face.
 
/ Kubota rear axles/differentials #12  
Slowzuki, failure started over a year ago. At that time, I was hauling a tank of water on a 3-point fork lift over somewhat rough surfaces (since the front axle was "floating" on the ground, an acquaintance said if I was relying on skid-steering I was overloading). I noticed a crack starting, on the top of the hydraulic cylinder case, above the lift arms' shaft, and parallel to the shaft. After consulting several knowledgeable welders/etc., I put a metal strap "bridge" across the fault line. To anchor the bridge I used two original bolt locations - and went on happily for a year not even thinking about the repair; and, ceased hauling "overloads". Then, two days ago, I was using the post hole digger. Although the auger was turning, in other words, it had not screwed itself into something, the Kubota wasn't pulling it out of the hole - as deep as the auger is long. Since the loader bucket was not attached, I assumed that's why the front end was up in the air! Soooooooo, I pushed down on the front (I weigh-in around 190 pounds.) and heard the awful CRACK. (My "bridge" ripped into two, along with the case). My point/wish is: when an operator, as MyJoBota points out, is capable of (over-)loading machinery, it would be nice if the weakest link in the chain was not an integral part of the machinery! Slowzuki, thanks for the heads-up ... I'll cancel any plans to buy a back-hoe attachment.
 
/ Kubota rear axles/differentials #13  
If you use a backhoe, get a subframe type. The problem with the top link in compacts of that age is they use the original ferguson type linkage, the piston inside that area puts a lot of strain on the casting, as well tension loads on the top link pull on it as well.

Driving on rough terrain will put higher loads than what you can actually pick up on the area too. There is not relief valve on that piston.

The new Kubotas use external cylinders and a beefy plate / bracket in this area and seems to have solved this problem.

Its also possible your relief valve for lifting has been turned up or shimmed causing your hitch to be able to lift more than it should.
 
/ Kubota rear axles/differentials #14  
Slowzuki, thank you for the overview of this kind of problem/issue. Your reply satisfies my original reason for posting. I'm sending a link to this thread to another New Member who posted with what sounds to be a similar problem/issue. In retrospect, I think I could still be in business with my Kubota if I had "bridged" over the failure with a thicker plate, beefy, in your terms:thumbsup:!
 
/ Kubota rear axles/differentials #15  
With the idea that bending an axle would fracture an imaginary extension to the casing ... what do you experienced folks say about this situation? My 17hp Kubota managed to (over-)load it's 3 point system to such an extent that it now has a ruined [fractured in two] hydraulic cylinder case and a badly damaged top rear edge on the differential case; the edge damage is a consequence of the hydraulic cylinder case getting ripped off of the tractor.
Looking at the damage causes me to wish the tractor had been designed so that an (over-)load would break the lift arms rather than allowing them to transfer the (over-)load to their shaft which then fractured the hydraulic cylinder case.

I would say that even when overloaded to the point of failing the TPH, the axles maintained structural integrity.
 
/ Kubota rear axles/differentials #16  
Were you using a logging winch or 3 point backhoe? Common damage from that type of use on compacts.

+2

JUADRO: so how exactally did that happen???

EDIT: Nevermind. I see you already answered it.
 

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