How to hook up hydraulic/hydrostatic pumps to engine

[Popeye1]

I have been thinking about converting my old skidsteer from a direct drive over to a hydrostatic drive for a while now. (in fact I have discussed it on here).
My engine now is an old wisconsin gas one that was rebuilt, but not very well done (I don't think it will last). Also, it is a direct drive wet clutch type of drive for these old skid steers. Whenever I need a part is it very expensive and the engine has a tapered shaft to fit the variable speed sheave.
I want to have a plan in place so that if/when something expensive breaks I can just convert it over to hydrostatic instead of putting more money into an old failing system.

Here is my plan so far:
Find a diesel engine with a few more HP (might have found one already for a steal of a deal).
Use two of these hydrostatic pumps: https://www.surpluscenter.com/item.asp?item=9-8238-R&catname=hydraulic
one of them to drive each set of wheels.
And I already have a nice vane pump to power the boom/bucket/hydraulics.
Here is the problem:
How do I go from the shaft of the engine and split it three ways (2 hydrostatic pumps, 1 hydraulic pump)?
I know it will probably come down to pulleys and belts, but I can't seem to figure out a way to do it without driving a jackshaft also. The less moving parts the better.

Any ideas? Other than buying a newer machine....

 

[JohninCT]

Not sure how much room you have around the engine shaft, but one idea is to mount a 3 belt pulley to the the engine shaft and mount the pumps on brackets around the shaft each offset to align with the drive pulley.

 

[Stimw]

I don't think you need to drive the hydros, you just need to supply hydraulic pressure and rerturn to them and a control stick.

 

[crazyal]

A lot of equipment will have the hydraulic pump mounted to the front pulley. Not sure if that would be an option.

 

[BHD]

there are stacked pumps made, not sure how your planing on the hydro stadic,is planed,

you may consider getting your machine in reasonable running condition, and selling.
Then buying a newer unit, with hydro static drive, may end up being cheaper and more reliable, in the long run,

 

[Kernopelli]

Aren't you meaning you want to use 2 hydraulic wheel motors ( not pumps) to drive each set of wheels? If you have a large pump already, you use it to provide all of your hydraulic flow and pressure and proportion it to wheel drives and FEL control valves.

 

[Cord]

I just replaced the drive pump in my skid steer. It was a Eaton 72400 piston pump. There are a pair of these pumps, one for each wheel motor with a third gear pump for the hydraulics. I have high output, so there are actually two gear pumps. To activate the HO, a solenoid valve combines the two pumps together. The rebuilt drive pump cost me $1,500 so I have a hunch that it's a bit different from the motor you are planning to use. The wheel motors are a Poclain ML06 with planetary gear reduction and a double chain sprocket splitting the power to each wheel. The older skid steers (not nearly as old as yours) would use a third chain instead of the planetary gear set. Obviously the chain isn't as reliable and breaking it means the machine can't move. I'd set a budget of $5,000 for your project. After you buy drive pumps, motors, chain, valves, hoses, adapters, etc. You'll have that much in the project. In all honesty, the machine isn't worth the investment. I'd sell it before it breaks again so you can maximize it's value and then buy an older skid steer like a a Gehl 3510 or something similar. This class of machine isn't terribly valuable because of it's smaller size and gas engine, but the hydraulics are all modern and very productive.

 

[Popeye1]

Thanks for all the input. Just to clarify a few things,
I am planning on 1 variable pump to power each wheel (making it hydrostatic), and a third vane pump for all the normal hydraulic functions. I actually already have the motors to drive the wheels and the vane pump for the other hydraulics. If I use the hydrostatic pumps that are in the link it is about $250 for both of them. The only other expense I will have are the hoses, fittings, and a couple sprockets.
I know I could sell and buy another machine, but cash is tight right now, and I am looking into this option because I enjoy working on and building things myself.

 

[Popeye1]

Aren't you meaning you want to use 2 hydraulic wheel motors ( not pumps) to drive each set of wheels? If you have a large pump already, you use it to provide all of your hydraulic flow and pressure and proportion it to wheel drives and FEL control valves.

I have considered one pump with flow dividers and valves, however, from what I can figure out it doesn't give very precise control and many people have problems with splitting the flow, etc. That is why I want to do it how the manufacturers are doing it with three different pumps.

 

[oldnslo]

Popeye1,
What size and how hard do you use this skid loader? The inexpensive HST units from Surplus center are not designed or meant for hard continuos use such as cleaning a barn, moving dirt piles, etc.

Eaton, Sauer Danfoss, Rexroth, etc. all make pump assemblies designed for skidloader service but they are not inexpensive. You can possibly find rebuilt units at places like:

ETS Hydro in Memphis

Attica Hydraulic Exchange in Chesterfield, MI (Detroit)

Hydraulic Parts Source in Michigan

To use one of the above places you would probably need some idea of a model code.