Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak

   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #11  
What do you consider the fault to be in this design? For some reason Kubota seems quite attached to it and I personally like the obvious benefits of this design. Of course I haven't had a leak yet.
 
   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #12  
The grand L front axle was a departure from previous designs - which were inherently stronger because the king pin housing was in double shear, with bearings above and below the axle joint. The grand L kingpin joint is cantilevered. I wouldn't go so far as to say it is a faulty design, it just doesn't have as big a strength margin, and with vigorous use it seems to have had a higher incidence of seal and bearing failures.
 
   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #13  
Is this true of the other L models?
 
   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #14  
rbargeron said:
The grand L front axle was a departure from previous designs - which were inherently stronger because the king pin housing was in double shear, with bearings above and below the axle joint. The grand L kingpin joint is cantilevered. I wouldn't go so far as to say it is a faulty design, it just doesn't have as big a strength margin, and with vigorous use it seems to have had a higher incidence of seal and bearing failures.

Dick please explain "double shear" are we talking stacking pressures on the axis in the joint itself or tensile strength of material? Interesting statement please follow up, Ob1..
 
   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #15  
Ob1kubota said:
Dick please explain "double shear" are we talking stacking pressures on the axis in the joint itself or tensile strength of material? Interesting statement please follow up, Ob1..
I may not be using the term double-shear correctly - but on the earlier L-series front axles, there's a second shear connection supporting the hub above the axle joint. The first pic shows the arrangement on the smaller models
Doubleshearhub310x246.jpg


The next pic is the more robust axle/hub design used on the L3750 & bigger L-3 models - more evidence of why I'm a die-hard L-3 fan. (Have two L5450's)
L3hub320x240.jpg


P.S. To borrow an idea from Curtisfarmer, TWO L5450'S = ONE L10900
 
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   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #16  
I don't see how that would have an effect on stacking pressure....if I'm understanding stacking pressure as simply the vertical load on the joint.

Let me see if I can think through this: I can see how having an attachment point above and below the axle would give the joint strength in terms of lateral loads... loads that would be in the same plane as 'camber'...for lack of a better word. A 'double sheer' arrangement would give strength resisting forces that would affect camber, and thus spread those forces to bearings above and below the axle, not just below.

These types of loads occur (if I'm thinking about this right) primarily when the tractor is turning. I think in particular when making a tight turn with a full load in the bucket, those forces are very high on the inside wheel. The camber (which is not adjustable) on my L4400, seems extreme to me. The top of the tire sets out wider than the bottom. I'm assuming this provides a tighter turning radius. But, when you have a heavy load in the bucket and make a tight turn, you can see that load's effect on the sidewall of the tire, pushing the bottom of the wheel/tire inward. So it seems to me that in these set ups without the 'double shear' design, a little more neutral camber would put less force on those lower bearings when turning with a load. But hey, I'm no engineer.

Anyway, I may have got this all jumbled up, but it seems to me that for those of us with this type of design, we need to take most care when turning with a load in the bucket.

It looks like the MX5100 and the M series tractors have this double sheer set up and none of the L or Grand L's do. But I may be wrong, this is just from looking at the rather poor photos on the Kubota web site.
 
   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #17  
N80 said:
..............It looks like the MX5100 and the M series tractors have this double sheer set up and none of the L or Grand L's do..................
Yes, the bigger tractors use this stronger design.

I think you are onto something in your ideas about camber and turning with a load. Looking at the cutaway drawing above, it appears to have a lot of camber to accomodate the kingpin angle & large upper bearing. I've noticed the tires on the L3600 get really mashed turning with a load.
 
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   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #18  
N80 said:
I don't see how that would have an effect on stacking pressure....if I'm understanding stacking pressure as simply the vertical load on the joint.

Let me see if I can think through this: I can see how having an attachment point above and below the axle would give the joint strength in terms of lateral loads... loads that would be in the same plane as 'camber'...for lack of a better word. A 'double sheer' arrangement would give strength resisting forces that would affect camber, and thus spread those forces to bearings above and below the axle, not just below.

These types of loads occur (if I'm thinking about this right) primarily when the tractor is turning. I think in particular when making a tight turn with a full load in the bucket, those forces are very high on the inside wheel. The camber (which is not adjustable) on my L4400, seems extreme to me. The top of the tire sets out wider than the bottom. I'm assuming this provides a tighter turning radius. But, when you have a heavy load in the bucket and make a tight turn, you can see that load's effect on the sidewall of the tire, pushing the bottom of the wheel/tire inward. So it seems to me that in these set ups without the 'double shear' design, a little more neutral camber would put less force on those lower bearings when turning with a load. But hey, I'm no engineer.

Anyway, I may have got this all jumbled up, but it seems to me that for those of us with this type of design, we need to take most care when turning with a load in the bucket.

It looks like the MX5100 and the M series tractors have this double sheer set up and none of the L or Grand L's do. But I may be wrong, this is just from looking at the rather poor photos on the Kubota web site.


George I'm going to respond but I'm going to my office to get a couple text books and review mechanics of material and bearing load computation. Double shear to my way of education is putting stress at both upper and lower bearings on the steering axis to the point of possible elastic limits. If I only knew the strength of materials and had a scaled drawing, I could put some math behind where the rubber meets the road. I'm interested because I own an L series with a beveled gear case design and I'm hearing noise at only 200 hours with only 500 pounds in the FEL turning to the left. I don't like replacing part without understanding why. I don't run it very often because my M Series does the heavy work around here.
 
   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #19  
You may find out more than I can understand, but I'm willing to give it a try and I appreciate the effort. Also, I guess there are two issue to consider. One is bearings, which some people have had to replace, but the other is just the seals. I'm not sure how the mechanics actually affect the seals.
 
   / Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak #20  
whitefacenh said:
I hasve a 2000 L3710HSTC w/ approx 500 hours. it has developed a small drip/leak on both sides of the front axle on the bottom of the bevel gear housing. Has anyone had experience with this and how hard it it to repair?

Thanks in advance for any help
Not to get you guys off topic here but, you are talking about axle leaks. Hoping to get a quick reply from someone.

I was wondering if anyone has corrected a front axle pivot leak with a simple adjustment of the pivot nut / pin??

At 450 hours I have a bad leak that just started under the front axle pivot area of my BX 1500. I just received my shop and parts manual.

Has anyone taken this assembly apart if so how straight forward and time consuming did it turn out to be?? It looks like just remove the steering control arm and pull the pivot bolt with some collars and O-rings straight out.

I'm also considering going with 90 weight gear oil instead of the thin SUDT.

I will be working on it very soon. Thanks for any input. :cool:
 
 
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