Anybody a hydrostatic drive guru

Looking at changing the vari drive on my self propelled baler to a hydrostatic drive hooking it to the 3 speed transmission with some kind of valve to change speeds between gears I'm not sure how much torque I will need and how much pump pressure and do I need a oil cooler any help would be greatly appreciated

Need some more information to tell you much. Biggest one is what is the power rating of the engine on the baler?

Most hydrostatic drives use a variable displacement pump driving a fixed displacement motor. Your easiest solution would be to find a drive setup off a smaller combine. It would be wise to have an oil cooler. The cooler would be plumbed into the case drain return from the motor and pump.

You need to salvage a complete system from a similar sized machine. How much horsepower does your baler have?
Not simple, but not impossible.
Hydrostatic motor chain couplered to your 3 speed trans input shaft. Pump driven by your engine.

Open your e-mail and I will send you photos, have setup from the motor back. I salvage equipment for the engines, sell used engines. Have several hydro drive pumps, couplings tanks , coolers or what ever in Tennessee.

Ok I'm trying to set up my email it is
[email protected]

The engine is a Ford 240 six cylinder about 65 hp

I've been designing machines with hydrostatic drives for a major OEM for many years so have quite a bit of experience with them. I will caution you that diving into such a project as you describe without a very good understanding of everything involved could easily end in less-than-desirable performance or (worst case) a very expensive learning experience. The components of a hydrostatic system are by nature quite expensive and in many ways are rather unforgiving of errors. I'll give you some hints here but more as an overview, not a step-by-step guide on everything you need to consider.

The first question to ask yourself when sizing your components is how much power do you want to deliver. Don't focus on torque - power is what really matters. After determining your desired operating pressure (typically in the 2500 psi range for a decent-sized hydrostat) you can then calculate the necessary flow rate to deliver the power you're needing. Once you know the flow rate you can then select a pump displacement that can deliver that flow rate at the speed that you'll be running it at. (Note that for hydraulic drives that flow, pressure, and power have the same relationship as rpm, torque, and power do when talking about mechanical power.) In the same way you use the flow rate to select a motor that will deliver the desired rotational speed at the pump's maximum displacement. The motor displacement can also be used calculate the maximum torque that you'll be able to deliver into the gearbox at the pump's relief pressure. Note that this peak torque will be about double the normal operating condition since you want the operating pressure to be well below the relief pressure to give you plenty of reserve capacity.

A closed-circuit hydrostatic drive also requires the use of a charge pump to keep the loop full of oil. Many hydrostatic pumps have a built-in charge pump which obviously simplifies the installation so be sure to verify this before buying a hydrostatic pump. It is critical to have a filter between the charge pump and hydrostat, something in the 10 micron range that is capable of 500 psi. The way this is plumbed into the system will be determined by the porting of your particular hydrostat. You'll also want a return filter that the case drains from the pump and motor are plumbed to.

Depending on the particular system and how hard you're working it it may be required to have a loop flush valve in the system to bleed extra oil from the loop for cooling. Some motors have a built-in loop flush valve that dumps oil from the low pressure side of the loop into the case drain. Since you won't know if your system will need added loop flush I wouldn't worry about this at the start - you can always plumb in a loop flush valve later if required.

And speaking of cooling you will almost certainly need an oil cooler to send the drain lines back through on their way to the filter and reservoir. Garden tractors and lawnmowers get by with just fans blowing on the hydrostat but for something like what you're looking at a cooler would be necessary. Plan to include a cold-oil bypass valve to prevent excessively high case pressures when the oil is cold and unable to pass easily through the cooler.

Thanks for all that information I'm trying to do the research I can work on em but don't know how to build one

If the variable belt drive can be rebuilt you might have pretty good trade-in value for tour old baler. It might be less expensive to trade your baler for one with hydrostatic drive and any other features you might want. What is wrong/broken on the variable belt drive?

I agree fixing the original drive is probably way more cost effective than your hydro plan. If you absolutely insist on going through with this I would suggest finding a salvage swather and adapt the complete system to your machine. You may even be able to find a unit that uses the same engine. Second option would be a hydro from an older smaller combine.

Am I missing something? This is a self propelled baler. Isn't that something that New Holland tried in the 1960's but it didn't catch on, making this a relatively rare and unique machine?

I don't think you can just go out and trade for one that has the features you want. Heck I don't think they ever made one with a hydrostatic drive period.

Unless I'm missing something and there's a huge self propelled baler industry that's been going on all these years... The only modern self propelled baler I'm aware of is the new Vermeer round baler that drives like a zero turn mower.

Something like an old Tennant parking lot sweeper might be a good starting point for all the parts, pieces and controls you will need for your project.

They don't make this baler any more and the parts to fix it are nolonger available the shaft and sheaves are worn so thought about making it hydrostatic

Find a OMC swather they had a ford engine and the Hydro and engine were the best part of the machine. Never had trouble with those.

The problem with a swather hydro drive is they are a dual pump and motor system, like a skid steer.

I still vote to gather parts off an old combine.

Manufacturers often buy assemblies like that from other companies to avoid the cost of engineering something they can buy off the shelf or custom order. That variable speed assembly was probably used on a number of other products including combines and swathers of the same vintage as your baler. You might be able to find some part numbers or casting numbers on the worn parts that you can use to trace down the original manufacturer and the other applications for your variable speed assembly. That should take much less time than engineering your own drive.