520H AWD Conversion

[mmmmmdonuts 274]

I have a 520H and was wondering if anyone has taken KXH-10 tuff torq front axle transmission to convert to AWD. These are commonly found on JD x749 tractors and possibly simplicity and other AWD GT.

 

The 520H has an Eaton 11 in it with a charge pump inside it. The thought would be to tap into the output of the charge pump circuit with a check valve and plumb in into the front axle.

1) Would this possibly work?

2) Does anyone know how the steering works with one of these? Is it a hydraulic steering as well or does the steering wheel go to a shaft on it?

3) What else am I missing? I know matching front and rear speed is critical but I wonder if you could fine tune it with a check valve going to the front axle.

 

I was just curious if anyone had any insight to this as a possible AWD conversion route as I possibly can pick one of these axles up for a few hundred $.

 

Thanks

[Achto 27,918]

My only knowledge of hydraulics is "they pick things up and put them down"  I'm tuning in for the learnin' though. 

[82Caddy 851]

Steering is hydraulic. I have the x748’s older brother the x595 with shaft driven 4x4. 
 

There is some other trickery in the hydraulics and steering to know to speed up or slow down one wheel based on speed and steering angle. I have no idea how that craziness works.  

[SylvanLakeWH 26,155]

[mmmmmdonuts 274]

49 minutes ago, 82Caddy said:

Steering is hydraulic. I have the x748’s older brother the x595 with shaft driven 4x4. 
 

There is some other trickery in the hydraulics and steering to know to speed up or slow down one wheel based on speed and steering angle. I have no idea how that craziness works.  

 

So if I used something off a power steering type tractor like my Bolens (Troy Bilt-GTX) has it maybe able to work possibly? That has a hydraulic cylinder that attaches to the side of the tractor to turn the wheel. The wheel attaches into the hydraulic valves to turn the wheels. So in theory if I were to take something like this and instead of putting it to the hydraulic cylinder it would go to the 2nd port on the front axle correct to turn and then the hydrostatic transmission output would go directly to the front. When I get a chance I am going to try and draw a hydraulic diagram and see if it makes some sense. 

[meadowfield 2,616]

Late to the party...

 

the charge pump is there to prime the variable displacement pump. There is no flow control - it just runs whenever the input turns. 

 

So you could use it to power the front axle - however it would run all the time and be constant flow, until you starved on axle  on oil.

 

Check valves will not control the flow rates you need, it has to be a pump driving each motor either individually or in series. Paralleling up will always drive the axle with least resistance - so it would skid.

 

If you could split the drive pump after the variable displacement pump and then drive both motors in series it could work - but thats not going to be easy.

 

 

 

Hope I haven't put you off - but I've spent a lot of time over the last ten years thinking and building 4x4 tractors, I've tended to stick with gears because of the hydro complexity (that and the fact we don't come across many hydro drives in the UK to play with)

 

mark

[82Caddy 851]

1 hour ago, mmmmmdonuts said:

 

So if I used something off a power steering type tractor like my Bolens (Troy Bilt-GTX) has it maybe able to work possibly? That has a hydraulic cylinder that attaches to the side of the tractor to turn the wheel. The wheel attaches into the hydraulic valves to turn the wheels. So in theory if I were to take something like this and instead of putting it to the hydraulic cylinder it would go to the 2nd port on the front axle correct to turn and then the hydrostatic transmission output would go directly to the front. When I get a chance I am going to try and draw a hydraulic diagram and see if it makes some sense. 

 I wish I were more help but I have no idea how the magic happens with those machines. 
 

Mark has a great response. He has to be part wizard or something to create what he does and make it look so easy. 

[mmmmmdonuts 274]

Thanks for the response Mark. Definitely have enjoyed watching your articulating tractors. 

To be honest I am more comfortable probably with Hydraulic vs the mechanical gear drive. Probably because my machining is not that great. 

 

When I built my loader for my other tractor I learned a lot about hydraulics and how they worked. Just wasn't entirely sure how a lot of these machines do 4x4. 

 

I thought of doing a similar articulating build similar to you using case/ingersoll hydrive transmissions which work entirely off hydraulics along with the implements. 

 

I was just curious because of the price point of getting the front axle for a few hundred $. It's the only reason I contemplated it to. Any other option seems to get very complex and expensive quickly. 

 

The only other thought was to attach an additional linkage to the hydro drive lever and use a flow control valve to control the flow to the hydraulics. 

 

 

https://www.surpluscenter.com/Hydraulics/Hydraulic-Valves/Flow-Control-Valves/3-8-NPT-0-8-GPM-Wolverine-Flow-Control-w-Relief-Valve-9-8993-37-8.axd

 

 

 

 

 

 

 

 

[ebinmaine 68,887]

4 hours ago, Achto said:

My only knowledge of hydraulics is "they pick things up and put them down"  I'm tuning in for the learnin' though. 

Me too, said the crane and forklift operator...

 

Interesting subject.

 

[Skipper 1,789]

Easiest solution would most likely be to use the entire x749 system, front and rear as the matched up unit it is. 

 

Just one small obstacle that springs to mind, out of a whole bunch, is that you need a very specific flow to have the front wheels go the right speed. it would be a very lucky shot, if the eaton charge pump had that exact flow. 

 

Making a 4wd system on hydro, is enormously much more complicated than making some pistons go in/out, or setting up a power steering valve.

 

I can only recommend to adapt a complete system.

 

Not trying to discourage, but chances that it will just work right otherwise, are extremely slim.

[meadowfield 2,616]

Using two identical drive motors/axles is the way forward with either a fixed pump or variable displacement. Fixed means you are purely stuck with forward/reverse at engine speed.

 

From what I know, something like the Case 444 axles work well - I think Bob Rock uses them as they can be driven separately from a pump.

 

That solves many if not all of the issues, the only remaining one you would have is where to tap the feed for the steering... as when you turn, the orbital will release pressure from the drive motors if you are sharing...  that means you will stop or slow down.

 

Most tractors have at least two pumps, one for drive and one for steering. My JD does share the rear 3 point with the drive - so if you try lift a weight on the back driving it does nothing until you take your foot off the gas!

[mmmmmdonuts 274]

Thanks for the information. Most of it is what I kind of figured as far getting it to work without buying a 4wd tractor. Not discouraged, just like tinkering probably too much. 

 

Basically you go and convert into an articulating tractor which seems to be the much easier route versus trying to have a standard tractor frame and do it at least to do a conversion. I am guessing articulating tractors help with uneven surfaces and even allow you to get into much tighter spaces with a tighter turning radius.  

 

The goal would be to put a loader on this type of tractor anyways as my current 2wd GT with a loader is great in most situations except handling my extremely hilly yard and wet yard in the back. Level surfaces, snow removal and in the front yard it does great. The backyard and wet hilly woods is where I get into trouble most of the year. Wheel weights, loaded tires, chains, 400lbs+ off the 3 pt hitch typically do fine except when I put several hundred pounds in the front bucket, I lose some traction in the back because of all the extra weight on the front. 

[Skipper 1,789]

Be very careful using an articulated for a home made loader. When you turn, you displace the counter weight, some forward, and a lot sideways. Dimensioned wrong, and they are prone to sideways tip over and roll. Ouch! At least, put on a ROPS if you go that route.

[ebinmaine 68,887]

I'd have to agree with the articulated and its issues with Static loading vs. Dynamic loading.

 

Look up diagrams of the safety triangle on a forklift type truck. That safety triangle would be moving around constantly and could make for a very dangerous ride if not properly accounted for.

 

Like above, I'm not saying it can't be done. But if you're using 400 lb of weight I would instantly switch to 400 pounds of weight PER WHEEL. Not kidding.

When you change the location of the theoretical safety triangle is when you put yourself at risk of rolling.

 

[ebinmaine 68,887]

2 minutes ago, ebinmaine said:

When you change the location of the theoretical safety triangle is when you put yourself at risk of rolling.

It just occurred to me I could explain that a little bit better.

For most of the forklift trucks that are on the market right now there are two wheels at the front and two wheels at the back but the back wheels only have one centralized pivot point. That is one point of the triangle and each of the two front wheels are the other two points.

 

So if you take an articulated vehicle and imagine the safety triangle...then imagine that the back end of that vehicle is capable of moving back at a 30 degree to 45 degree angle or sometimes even more.

 

So just imagine what that would do to the back end of a safety triangle.

 

Anytime the center of gravity leaves that safety triangle you are going to roll. That is not negotiable.

 

So how do you compensate for that with an articulated vehicle?

One way would be that if you know you're going to put 400 pounds on the back of a vehicle that is not articulated, then you would need to make it so that 400 lb would appear to be at the back of the articulated vehicle at all times.

 

 

That was my reasoning for doubling the weight at the rear of the vehicle.

 

Overkill?

Not if it's keeping me from rolling over....

[meadowfield 2,616]

oddly, I never thought of this designing mine. From the math, it's obvious...

 

Mine is such a short wheelbase only pivots 30 degree max -  and has two 8 speed boxes, fat tyres and rear weights.It has never felt unstable - I've done some silly things looking back too!

 

thanks for raising a valid point.

[mmmmmdonuts 274]

I agree with this point. I never thought about it with an articulating tractor and how the load gets put off center. I guess that's why skidsteers are so small and can lift comparable weights to front end loaders which are much larger and weigh quite a bit more.