Backhoe Design Ideas

[J_J]

Yes, it should as you are only using half of the flow.

10 GPM's - 3600 RPM = .6 cu in = 21 HP required
5 GPM's - 1800 RPM = .6 cu in = 10 HP required

So if you ran 10 GPM through a flow divider, and had a 50/50 split, each circuit would get 5 GPM, but the one leg would only go to tank, and the other side would have 5 GPM at 3000 psi

Maybe one of these.

https://www.surpluscenter.com/item.asp?UID=2009092314505827&item=9-5911&catname=hydraulic

 

[Brad_Blazer]

Is there a model number on the pump? If you can look up the rated flow or displacement it is not hard to calculate the power and torque requirements.

If you have a big pump and big cylinders you can reduce the relief pressure to prevent snubbing the engine or destroying the machine.

15HP at 540RPM (PTO) means about 146ft-lb of torque. Let's say you have at least 106ft-lb available at low RPM. That is enough to drive a 4 cubic inch gear pump at 2000psi.

Here is a link with some hydraulic calculators and tables.
Hydraulic

 

[J_J]

Iplayfarmer,

Did you mention whether that PTO pump was a 540 or 1000 rpm pump?

 

[Iplayfarmer]

Is there a model number on the pump? If you can look up the rated flow or displacement it is not hard to calculate the power and torque requirements.

If you have a big pump and big cylinders you can reduce the relief pressure to prevent snubbing the engine or destroying the machine.

15HP at 540RPM (PTO) means about 146ft-lb of torque. Let's say you have at least 106ft-lb available at low RPM. That is enough to drive a 4 cubic inch gear pump at 2000psi.

Here is a link with some hydraulic calculators and tables.
Hydraulic

There's no model number, but it has "Webster" stamped in two places on the housing.

You might have the answer: bigger cylinders and lower relief pressure. I guess that if I used bigger cylinders then I could simply adjust the relief pressure to match the power of the tractor. If I find that I have power to spare, I could simply increase the relief pressure and have more force to work with.

Flexibility and adaptability are big in my book.

Iplayfarmer,

Did you mention whether that PTO pump was a 540 or 1000 rpm pump?

It's 540.

 

[J_J]

Does this look like your pump?

 

[Iplayfarmer]

Does this look like your pump?

That Looks like it. Except mine has ports coming out the side.

 

[J_J]

I am used to seeing the PTO pumps like the ones by Prince. However, your Webster pump, looks like a regular hydraulic pump with a a PTO shaft adapter on it. What I am thinking, is that they are using a large cu in pump, and just running it at 540, or whatever the PTO rpm is. With 18 HP available, and a pump pushing 9 GPM, at 3000 psi, would require a pump with a displacement of 3.9 cu in. while turning at 540. If the pump displacement is larger, that means that you could use less rpm on the engine.

How much HP did the other guy have on his tractor, and maybe I can figure the size of the pump. The Prince PTO pumps also pump at 2000 psi.

 

[Iplayfarmer]

I am used to seeing the PTO pumps like the ones by Prince. However, your Webster pump, looks like a regular hydraulic pump with a a PTO shaft adapter on it. What I am thinking, is that they are using a large cu in pump, and just running it at 540, or whatever the PTO rpm is. With 18 HP available, and a pump pushing 9 GPM, at 3000 psi, would require a pump with a displacement of 3.9 cu in. while turning at 540. If the pump displacement is larger, that means that you could use less rpm on the engine.

How much HP did the other guy have on his tractor, and maybe I can figure the size of the pump. The Prince PTO pumps also pump at 2000 psi.

His tractor is a Massey 85. I think that's about 50 hp.

 

[Brad_Blazer]

You could put some short hoses on the pump, prime it, and turn it by hand say 10 revolutions to measure the output in a graduated bucket or big measuring cup. 1 cup = 14.44 cu in.

 

[J_J]

A 50 HP engine can run a 25 GPM pump at 3000 psi, at 540, and the pump displacement should be around 10.5 cu in.