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Discussion Starter · #1 ·
I have a question that maybe some of you can help me with.
I have a 4 wheel drive tractor that I built ( the one on the left ) and I am not happy with the Eaton # 11 hydrostatic drive transmission that I put in. I would like to change it to a hydraulic pump hooket to the 27 hp. motor. Then hook up a hydraulic motor up to my transfer case. Her is my question the unit that I put between the pump and the hyd. motor should be a ( flow directional control valve )( motor spool valve ) open center valve? The unit will need to contol the hyd. motor speed and direction ( rotation ).
Question #2 On the hyd. pump the higher the cu. in. that means the more the power? Like a 1.37 cu. in. pump is not as powerfull as a 3.3 cu. in. pump?
Thanks
Mark in Vermont
 

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Mark

I've been thinking a little about your "transmission".
The Case / Ingersoll garden tractors use a hydraulic motor to drive the rear axle instead of a hydrostatic transmission.
They just use a regular open center hydraulic valve to operate it.
The more you open the valve , the faster the hydraulic motor turns.

Push the lever forward and the tractor goes forward, pull it back and the tractor reverses.
Center is neutral.

Don't know if that information will help you at all, just thought I would throw it out there for whatever it's worth.
 

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the valve on my colt is open center, basicaly the everyday valve. i'm sure there is a fancy way to do it but..... the drive offers no braking. On the pumps, the bigger dis. just adds more volume, = speed. pump max pressure sets working force, = torque.
 

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One other thing to think about is a holding valve .Cause the Case tractors that don't have them have a tendency to gain speed on the down hill dives. You can lightly retard the Travel Control valve and stop the run away. You can use a flow control valve in front of your directional valve to more accurately control speed. Case Tractors recommended and put them on units with rototillers for more accuracy in maintaining slow speeds. Although the Case/Ingersolls TCV valve do have extra long travel and can control speed alright, sometimes it could be better. So I say investigate how the Case/Ingersoll 600 or 6000 series tractors are set up. They have worked out how possibly best to do it. Take into consideration that they only work on 8-11 gpm. at around 2000 psi. depending on power steering on the gpm. But definitely a holding valve or hold on . Well that's my 2 cents anyway.
 

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What you have to watch out for is that a hydraulic motor acts like a hydraulic pump when you shut the valve off and the tractor still has momentum. You have to plumb in relief valves to allow for this or you'll build up excessive pressure and blow lines or the motor. Typically this is done with a "cushion" valve which is essentially two relief valves set in opposite directions.
 

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Mark, yes you would want a motor spool valve. As Chagrin mentioned, sudden jolts from a valve opening and closing on motor can cause damage. Do not confuse open center and tandem center valves, as many call a open center when trully is tandem center. Tandem has open port when centered allows hyd. fluid flow but yet hold lets say the loader up in air. Open center allows all ports to lets say relax when centered allowing pressures to disapate, such as a motor spool valve.
As far as pumps, the size gives you more potential. Rule of thumb, 1 HP gives power to flow 1 GPM at 1500PSI. 2 HP gives power to flow 1 GPM at 3000 PSI.
231 cubic inches to galon. If you had pump at 2.31 cu/in 100 revs gives 1 galon. That would be a big pump. You would not have enough motor to run that pump even at 1500 PSI.
I am wondering if you did not mean hyd. motor size when you mentioned on the sizes of 1.37 and 3.3 cu/in.?? Motor size will have to be determined by desired speed, torque needed, and flow from pump flow you have or will have.
 

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Discussion Starter · #7 ·
Thank You for all the help everyone.

Murphy what I am looking at is a ( single spool 30 GPM brand OC control valve W/flow control ) It is a 4-way directional control valve with a full range, pressure-compensated, by-pass type flow control valve and a pilot-operated relief valve. Extremely fine flow metering to the work ports in direct proportion to the handle movement. This is from Surplus Center ( Item # 9-7497-30 )
Thank You for your help
Mark
 

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Discussion Starter · #8 ·
Mark, yes you would want a motor spool valve. As Chagrin mentioned, sudden jolts from a valve opening and closing on motor can cause damage. Do not confuse open center and tandem center valves, as many call a open center when trully is tandem center. Tandem has open port when centered allows hyd. fluid flow but yet hold lets say the loader up in air. Open center allows all ports to lets say relax when centered allowing pressures to disapate, such as a motor spool valve.
As far as pumps, the size gives you more potential. Rule of thumb, 1 HP gives power to flow 1 GPM at 1500PSI. 2 HP gives power to flow 1 GPM at 3000 PSI.
231 cubic inches to galon. If you had pump at 2.31 cu/in 100 revs gives 1 galon. That would be a big pump. You would not have enough motor to run that pump even at 1500 PSI.
I am wondering if you did not mean hyd. motor size when you mentioned on the sizes of 1.37 and 3.3 cu/in.?? Motor size will have to be determined by desired speed, torque needed, and flow from pump flow you have or will have.
Murphy
I have a hydraulic motor that I may use but can't find any info on, can you help?
On the hydraulic motor ( Ross MAC012997 ). What I need to know is RPMs and what the torque is. Also GPM.
I found one on e-bay that was for sale and the only thing that is had was that the motor was a 12 cube motor.
Thanks Mark
 

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Mark, do you know what it came off of?? I could not find anything on it either. Some of these pumps, and motors in the past on some things are marked differently then you would expect. I sent you a private message for another forum that may have some info for you.
 

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Discussion Starter · #10 ·
Mark, do you know what it came off of?? I could not find anything on it either. Some of these pumps, and motors in the past on some things are marked differently then you would expect. I sent you a private message for another forum that may have some info for you.
Thank Murpy

The hydraulic motor came off a small road paving machine. The motor was hooked up to a chain drive 1 to 1 ratio. The tires were about 16" to 18" around. The name of the machine I can't tell you. The machine was all cut up. The unit did go foreward and back. If I new the RPM's I could make the gear box so that the tractor speed was ok. I also will need the GPM to size the hydraulic pump.
I will take the motor to a hydraulic man today and see if he can help.
Thanks again for you help
Mark
 

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Mark,here is a bit for you to think about.
Displacement of hydraulic motor, or cubic inch per revolution (volume) can be calculated.
Experiment with motor inlet port up. Feed oil by gravity from an over head container. Shaft should be turned slowly by hand while counting revolutions. The higher the revolutions count and known amount of tranfered can give good estimates on size of displacement.
Example: 25 revolutions gives 1 quart transfer of oil.
231 cu. in. per gal/4 qts. per gal./25 revs.=2.31 cu. per revolution.
Will not be 100% accurate due to leakage, e.t.c.
Torque is directly proportional to PSI.
Calculation of motor characteristics.
D=Displacement
T= torque
~= we will say pie 3.14
1 Torque developed on shaft T=D x PSI/24 x ~
2 HP out put HP= D x RPM x PSI/395,991
3 Oil flow for a desired shaft speed GPM = D x RPM/231

Of course this does not reflect on manufactures spec on all motors for they will very for PSI intentions and speeds.

Is the pump you have a fixed or variable displacement? Vane, gear, or piston?
 
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