Hydraulics Help Needed

[Coon]

About a year ago I started to build a low ground pressure rubber tracked skidder that I was going to mechanically drive using a complete steering clutch system out of an old self propelled grain swather.  The system was going to be larger than I wanted but I knew it would work and was going to be a very very large project to complete.  Since then we moved about 60 miles, from where we were located, due to availability of work and such.  During the move I lost the majority of the plans I had drawn up for the unit.
   Anyways,  I got to thinking more and more about the unit and how large and heavy it was going to be. With having to draw up a new set of plans I decided to go another route.  I will be going ahead with a hyraulic drive system.  I want to keep as much weight to the front as possible so I will be putting the engine in the front.  I will also be driving the tracks from the front too.

  Here is what I am looking at.  The engine I will be using is a 1.6L (1590 cc) h4 Subaru "boxer" engine to drive the hydraulic pump(s).  The engine is rated at 67 hp @5200 RPM and has 81 ft.lbs of torque @ 2400 RPM.  I want to achieve a maximum of 12-15 mph as I will be eventually using this unit to pull a forwarding trailer along with skidding out sawlogs and pushing snow.  My drive wheels are 18.5 inch diameter. 

  I have decided to run 2 separate hydraulics systems; 1 for the drive system and another for the auxillary hydraulics.

  What should I be running for a system for the drive?  Open or closed centered circuit? What should I need for GPM (gallons per minute).  I was planning on using a chain drive system  from the motor to the drive wheel.

What should I be running for my auxillary system? Open or closed centered circuit?  I want to have 2 remotes to the front and 2 remotes to the back.

Any and all help is very much appreciated.
Brad.

[Gary_C]

That sounds like a very large and complicated job you are undertaking. If you really want to build a hydraulic drive, I would suggest you buy an older hydrostatic drive combine. They are selling them for scrap metal prices including a heavy duty drive train, motor, and auxillary hydraulic system. For example, I have an IH 815 gas engine combine that has not run for years. I was going to sell it to a salvage yard and all they really wanted was the International 345 ci V-8 engine. I think all he offered me was $600 and it would have cost me $200 to haul it to him. Right now it is worth more than that just by the pound.

You could not make a complete hydraulic drive system for what you can buy an older combine that has everything you need and some leftover metal that is good for the scrap man.

[Haytrader]

Gary_C........that is very good advice.
I have seen L Gleaners sell at auction for $200 that started and ran. I was thinking of doing somthing with one myself.
A guy could drop the header, take all the sheet metal off, and build a boom with a chain(s) for moving logs to the mill.  A little modifacation and it could have forks or a grapple.
The older ones that weren't hydrostatic drive are even cheaper. I have seen C or CII sell for under a hundred.
Maybe we should have a "junkyard war" and see who could end up with the most useful or best looking machine.
;)

[Handy Andy]

  You guys are right about old combines being cheap.  Having built a self propelled sprayer out of one, the only thing I would change is to have started with a better machine.  A John deere would be my choice for a sprayer as the back axle has more ground clearance than the IH I used.  I ran into an old school chum awhile back and he is planning to build a loader out of one.  Seems like it might work, the drive wheels are in front, so the weight of the loader would be on the right end.  Jim

[Coon]

I have access  to three or four sheds that are waste deep in parts, mostly hydraulics in fact.  Besides combines go for alot more than that around here if they have any amount of useful parts left on them. 

The planetaries are way to big and heavy for what I need.  I want to keep my whole unit under 2500 lbs total.  The whole unit will be no more than 6 1/2 feet wide and 11 1/2 long w/o blade.  I am talking with a heated cab and everything. ;)

[Quartlow]

You defiantly want hydrostatic drive. Hydraulic drive will free wheel downhill. A good example of that is the old Case hydraulic drive garden tractors. Since your going track drive I do believe your going to need two hydrostatic pumps one for each side. I could be wrong. Case skid steers use two pumps. One for each side. No need to worry about controls, they are built in on most hydrostatic pumps.

As for the blade hydraulics I think it's just a personal preference as to open or closed center.

[J_T]

Have you seen how a Bell tree cutter is set up :-\

[Coon]

Can't say I have J T.