Hydrostatic Pump/Motor Combos

[CootATV]

Hey all,

Looking for some input: I have a vehicle known as a Coot ATV that I am in the process of repowering. I would love to change out the old 2-spd transmission with a hydrostatic drive pump/motor combo but i'm having a hard time finding suitable options. I figured that the folks on the tractor forums would be the best suited to recommend good units. The current engine is a 23HP vanguard vtwin, which uses a torque converter belt system to run the transmission; which then runs runs a set of worm gears. The rotation of the hydrostatic trans will need to be CW. The input/output shafts need to be parallel in order for the configuration to work.

The main hydro model I'm currently looking into is the Eaton model 11 hydrostatic pump/motor; however Its hard to find much information on these as far as a suitable donor vehicle rather than pay 3k for a brand new one.

Any input would be greatly appreciated.

(I apologize for the terrible photos, i'll try to get some better ones when i'm at the storage location)

Thanks,

Brendan

 

[hayden]

What's the motivation for hydrostatic? I ask because you will lose a chunk of power to it, and it will need oil cooling. I have a Kubota RTV with a 25hp diesel and hydrastatic drive. I real like it for my purposes, but it's a real dog. Specs are 25 mph which I have seen it do going down hill. But you can realistically expect 14-18 mph

 

[oldnslo]

Do a little homework on the Eaton series 11 since I believe some of the models are no longer in production and parts are not supported either. Would also verify rated input and output HP since these were frequently made for lawnmower type use with very little HP capability.

Hydro gear is another company but I am not real familiar with their product line.

Like Hayden stated with multiple gear ranges behind the HST you will lose either low end torque or top speed or both.

 

[MossRoad]

Do a little homework on the Eaton series 11 since I believe some of the models are no longer in production and parts are not supported either. Would also verify rated input and output HP since these were frequently made for lawnmower type use with very little HP capability.

Hydro gear is another company but I am not real familiar with their product line.

Like Hayden stated with multiple gear ranges behind the HST you will lose either low end torque or top speed or both.

I agree with this.

My machine is all hydraulic. I have 4 wheel motors, one at each wheel, powered by a variable volume pump that's turned by a gas engine.

It's a compromise between torque and speed.

The only way to get more torque would be to get larger displacement wheel motors. But that would cut top speed.

The only way to get more speed would be to get smaller displacement wheel motors. But that would cut low-end torque.

Since my machine is primarily used for mowing and moving material from one place to another, it does not need low-end torque, like you'd need for pulling a plow, or high-end speed, like you'd want for road travel. So the manufacturer settled for a happy medium.

HST tractors have a pump that is spun by an engine. That pump spins ONE motor that turns the shaft in the range selector. The range selector then spins the rear end differential.

So in effect, on an HST tractor, the range selector is a geared transmission with two or three ranges.

Just something to think about...