hydraulic motor spec comparison help

[pairofhounds]

How do these hydraulic setups compare? Need one of the hydraulic gurus to help. I'd like to use a 8.0 104-1063 motor with a 100 hp gearbox with a 1:1.46 speed up ratio to produce similar results as a fixed displacement, cast steel gear motor with the following specs. The motor is rated at 90%+ efficiency. At 34 GPM and 3250 PSI the motor yields 1000 RPM and 4020 inch lbs of torque. Here is the specs of the motor Id like to use. 8.0 cu in CHAR-LYNN 104-1063 HYD MOTOR
Thanks! Bryant

 

[pairofhounds]

for a bush hog

 

[dfkrug]

You want to use that Char-Lynn motor at 34GPM and 3250psi? That's way beyond the max flow
for that motor, and your pressure operating point is getting out of the more efficient "continuous"
range.

 

[pairofhounds]

No, at normal operating speed it appears that I would get similar torque and rpm results with at my 24gpm flow and gearbox setup as the direct drive motor at 34GPM

 

[pairofhounds]

Basically want to duplicate results. Does that make sense?

 

[oldnslo]

Are you wanting to run 24 GPM continuous through the Char-Lynn motor? If yes that is pushing the upper limits of its rating. Attached are a couple of formulae spread sheets that you can use to figure hydraulic motor torque, RPM, etc..

 

[J_J]

Where does the 34 GPM come into play as the motor stated is this.

Flow:
20 GPM cont.
25 GPM int.

Pressure:
3000 PSI cont.
4000 PSI int.
Torque:
3420 in-lbs. cont.
4970 in-lbs. int.
Speed:
576 RPM cont.
720 RPM int.

He does not have to shove 34 GPM through the motor.

Reduce the flow to low flow or reduce the engine rpm to a 24 GPM rate.

He wants more speed, therefore, he is going to lose some torque.

 

[pairofhounds]

the specs that I'm trying to duplicate are actually that of a disc mulcher, kind of similar to a hydro ax cutting disc head. The RPM and torque specs of the two motors are comparable except for the fact that the direct drive motor can achieve the similar results at a higher flow... I know that flow is important but it appears that I can achieve similar output with less flow.. Also, not sure about the efficiency% lost by going through gearbox. I know this is confussing..... thanks for input!

 

[boggen]

calculators that might help you
Pump Disp., HP, GPM & RPM Surplus Center
Motor Speed, Torque & HP Surplus Center

 

[pairofhounds]

For instance: I dont see a whole lot of difference between the following 2 motors other than GPM and a bit of torque. Am I correct by saying they will produce similar results?

11.95 cu in CHARLYNN HYD PTO DRIVE MOTOR

8.0 cu in CHAR-LYNN 104-1063 HYD MOTOR

 

[J_J]

If you have 34 GPM , then go ahead and use the larger motor, with more torque.

 

[pairofhounds]

I already own the 8.0 motor and only have 24gpm

 

[J_J]

If you use the large motor with your 24 GPM it will run about half speed., but still have the torque.

 

[pairofhounds]

So, GPM affects RPM mostly?

 

[J_J]

Yes, that is correct, but if you add a gear box and increase the output speed, you lose torque.

So, if you run the 11 cu in motor with 24 GPM, your speed will be about 465.

That is close to a 1:1 gearbox on a bush hog.

 

[pairofhounds]

Off the shelf, are the 2 motors similar? Will the motor with the lesser 25 GPM max operate similar to the motor with 40+GPM if run at their capacity?

 

[J_J]

If you only have 24 GPM, that will limit your speed on any motor unless you do the gearbox thing.

The larger motor will have more torque.

If you run the large motor with your GPM, that will run a bush hog with about a 1:1 ratio.

Of course good sharp blades also help with quality of cut.

 

[pairofhounds]

I guess I will go ahead with the 8.0 motor i have. The surplus center specs are fairly close other than gpm.. the higher flow motor doesnt produce much more torque plus, I will have a 600lb blade carrier that will hopefully help with momentum. .

 

[oldnslo]

8 cubic inch motor at 2500 PSI differential presure produces 238.7 ft lbs torque @ 90 % efficient

24 GPM will spin this motor at approx 690 RPM

11 cubic inch motor at 2500 PSI differential pressure produces 328 ft lbs torque @ 90% efficient

24 GPM will spin this motor at approx 500 RPM.

Do a search for Eaton literature 11-01-878 This is the disc valve motor. You have a 2000 series

This literature will show you a chart that provides RPM, Torque Vs inlet GPM & pressure differential across the motor.

 

[pairofhounds]

one question. why doesnt the 11.95 motor require a case drain. It requires a hi flow unit to run it properly....