Hydraulic Motors?

[kdlklm]

I have got 4 hydrostatic motors that have a maximum flow rate of 15.9 GPM at 2030 PSI. To get the maximum performance out of them, would I not need a pump that can put out 63.6 GPM. Or am I misunderstanding the principle of how it works. The reason I'm asking is because the pump that was suggested for me to run these motors is 19.6 GPM at 1250 PSI.

 

[J_J]

Do you have hydraulic pumps are just hyd motors?

Do you mean variable speed pumps?

What is the name and model # ?


You would want the pump to match with the flow of the motor.

 

[J_J]

If they are hyd motors, it will depend on the way you connect them, as in series, parallel, or in a series parallel set up.

The Power-Trac machine that a lot of us have , use a series/parallel setup, using a variable speed pump/hydrostatic pump.

The 3000 psi is dropped across two motors in series on one side, and same for the other two motors.

If you install them in series, the flow in GPM will flow through all of them, and the pressure will be divided between the 4 motors.

If you put them in parallel, you will need about 60 GPM to fully run them at their rated RPM, and at their rated pressure to develop the HP needed.

Each of the motors will develop HP based on the GPM and pressure, and displacement.

The torque is based on the displacement in cuin and pressure.

 

[kdlklm]

I have attached the PDF files with all the specs of the pump and motors.

4 Hydro-gear Model HGM-08P
1 hydro-gear model PW

 

[kdlklm]

It appears now that I look closer at the specs, it will be tandem pumps, each pump will run one side of the machine. So each pump has two motors.

 

[J_J]

So you have both hyd motors and hydroatatic pump.

On the zero turn mowers, there is a pump for each motor.

Are you planning on using one pump and 4 motors?

Can you explain your plan on how you want to use the motor and pump combination.

Essentially what you need to do, is to determine the HP that would be required to power what you want to build. If it takes 4 hyd motors that you have, you need to find a pump that will support the demand as to GPM and pressure.

The hydrostatic pumps have their own valves, so connecting the motors to pump should not be a problem. You then need a tank, and filter system.

The engine that will turn the pump has to be selected based on the potential hp that the pump, can develop. If done correctly, you will need a little extra for the electric part of the machine. What size alternator on the engine or external alternator. Battery size, tire diameter and size, etc. What speed do you want?

These are just some of the things to consider when developing a project.

You might get some good ideas by looking at some of the zero turn mower schematic and parts.

My hyd machine needs about 45 HP to power a pump that will service 4 hyd motors, and a 3 GPM steering/lift pump, and another 13 GPM PTO pump.

 

[J_J]

Another thing to consider is, do you design the pump to power the left front and the right rear. If one pump fails, you can still move if you activate the tow valve on the failed pump.

If one pump feeds two motors on the same side, and one pump fails, can you move or can you get home?

Is all this for work or pleasure.

 

[kdlklm]

The design is to have a tandem pump that runs to hydraulic motors on the left side and to hydraulic motors on the right side. I will attach the spec sheet that was ran by hydro-gear for the system design. I plan to be running a 30 hp gas motor, the system will also use articulated steering requiring one hydraulic ram.

Does your machine use a gear pump or a piston pump. I'm thinking about going with piston pumps, they are a lot more expensive, but are supposed to be a lot more efficient.

The wheels will be 22 to 25 inch, and I'm hoping to get 20 to 25 mi./h out of it.

This machine is for pleasure.

 

[kubotakid USA]

Why do you want to run two hydraulic drive pumps? You can run all 4 motors on 1, So much cheaper, an simple ta boot. I have a small 4x4 road grader, Its got a hyd motor on each wheel, and >1< hydrostatic pump.:thumbsup: Eric

 

[kdlklm]

Why do you want to run two hydraulic drive pumps? You can run all 4 motors on 1, So much cheaper, an simple ta boot. I have a small 4x4 road grader, Its got a hyd motor on each wheel, and >1< hydrostatic pump.:thumbsup: Eric

That sounds interesting, would you be able to post some photos of that machine, or even get me the make and model number so I can look it up. Do you know what size of pump that it's running.

 

[kubotakid USA]

pics of hydrostatic 4x4 grader Eric

 

[kdlklm]

Do you have any specs on that pump. What kind of speed does it get.

 

[kubotakid USA]

Do you have any specs on that pump. What kind of speed does it get.

No, It wouldent do you any good anyway, this machine weighs maybe 8000 lbs, and has a 4cyl diesel engine, You can you tube puckett bros grader 510 and see one in action, The point is, Its a 4x4, hyd motor on each wheel, And >1< hydrostatic drive pump. I also have another 4x4 machine setup the same way, Jacobsen LF 3810, 4x4 was an option, I dont understand why you want to complicate your machine with 2 pumps. Max speed on either one of these machines is about 10 mph, And you need about double that so specs off even the Jacobsen mower wont help much, The really cool thing about the jacobsen i that its a 2wd until you flip a switch and direct oil to the back axle, at that point it slows down, maybe 25%, so basically its like a transfer case in a 4x4 truck, only this is either 4x4 low or 2wd high. perfect for your application, you can get top speed in 2wd, or 4x4 at a slower speed.:thumbsup: Eric

 

[karlbike]

this is good stuff.
I'm looking at building a tractor similar to the Power trac T8 or T12.
I have a friend with a T8, but haven't jacked it up and looked too closely.

I want to Base it on this sort of power unit: Power Cube - Open Source Ecology

basically I'm building the power cube first, and setting up to build the machine (and others) to run off that power cube.

I'm looking to spec a pump that will run anything I can think of that would take less than 25 HP gas engine to run.

J_J, which power trac do you have and can I ask you more questions about it?

thanks
karl

 

[J_J]

I have the PT-1445, one of the older early 90's units with 45 HP gas engine.

That engine has to turn 3 hyd pumps for all the hyd functions.

That engine is capable of turning a 24 GPM pump or a combination of pumps, at a psi of 2750.

MY PTO pump is 13 GPM, and the steering and loader pump is about 1.5 GPM, so that leaves me about 9.5 GPM for the drive. Each wheel has a hyd motor.

I am usually not maxing the pump out all the time.

 

[kubotakid USA]

Do you have any specs on that pump. What kind of speed does it get.

KDLKIM, Iam gonna try to help you once again, with your wheel chair atv.. Remember, I have 3 good friends in wheel chairs, bad luck, It sucks, But they are my buddies, SO,..I want this to work as much as you do, You need to stay focused and decide what your gona do,. You posted that you had a hyd company hired, and its all good, a done deal,..then u post, what would you guys do?... That $htt aint gona work,..J,J has burned many candles, and so have I, and many others. Lotsa people wana help you and see this thing roll, SO Lets get back to work, and figure this thing out,.:thumbsup: .Eric

 

[J_J]

karlbike,

The most GPM from a pump driven with a 25 HP engine is 12 GPM, at 3000 psi.

The PT 425 uses a 25 HP engine for power.

 

[kdlklm]

KDLKIM, Iam gonna try to help you once again, with your wheel chair atv.. Remember, I have 3 good friends in wheel chairs, bad luck, It sucks, But they are my buddies, SO,..I want this to work as much as you do, You need to stay focused and decide what your gona do,. You posted that you had a hyd company hired, and its all good, a done deal,..then u post, what would you guys do?... That aint gona work,..J,J has burned many candles, and so have I, and many others. Lotsa people wana help you and see this thing roll, SO Lets get back to work, and figure this thing out,.:thumbsup: .Eric

I have got more than one company give me recommendations on what I should be using for pumps and motors and electronics, and they are coming back quite different from each other. So I'm only asking what other people think.

Things are very much on track, it's a slow process. things are moving along fairly well so far.

 

[kubotakid USA]

Therein lies the problem, too many cooks stiring, go with a guy like jj or kevin j, use the jacobsen 3810 schematic, 2wd for hi speed flip a switch and get 4x4 @ lower speed,.... smile- click- build,.. The deal has been done already, I would not follow the jak 3810 to the letter, as its pretty complicated, just use the basic drive parmeters, UUE dont need high speed 4 wheel drive,.. this is smart engineering, And your not going to the moon. these guys are plenty capable to help design your drive system.:thumbsup: Eric

 

[kdlklm]

the next thing on the agenda, is a parking brake. I was just looking for some thoughts on what might be some different options. I don't think I will need them on all four wheels. Probably just the rear ones will be fine.