Hydraulic pump & motor system design

[Rowski]

Need some help form the hydraulic experts and guru's. My goal is to see what it would take for HP to run a hydraulic pump on a PTO to power a motor to drive a snowblower. The "fixed numbers" in this equation is the motor to drive the snowblower needs to turn at least 540 rpm and deliver 40 to 45 hp, Hydraulic pump speed is 540 rpms. My goal it to find out what hp is required to make this thing work if at all possible. To me it seems the 540 rpm of the pto is to slow to give the pump enough power to run the motor.

I found this on the internet, its a small 4 page .pdf file.

Is this the right direction to be going in /forums/images/graemlins/confused.gif /forums/images/graemlins/crazy.gif??

Are there any other sites or books with this type of information?

Many Thanks!!!

 

[gone]

I'm not a hyd exbert but i do know your gona loose quite a few hp. just being fluid drive. prussere is power so a 540 is capable. slower speed more displacment. 540 out pump and 540 in motor would be very close to the same displacment,the pump may have to be slightly bigger to ofset restictive effect of hose ect. the best way to make power at blower is smaller displacement motor say half what the pump is speed 1080 rpm then reduce to 540 by gearing,that would give motor more torque to work with. Of course i could be all wet but it's an educated guess. For real results hyd. manufacturers are usualy avalable for your hyd. store to consult with. I'm just trying to give an est. of what your up against,trial and era can get very expensive when it comes to hydulics. please do your self a favor and consult a pro traind in the field.

 

[MossRoad]

So, you have a snow blower that requires 40-45 HP and 540 RPM and you want to run it with a hydraulic motor?

 

[DocHeb]

If the system was 100% efficient, I calculate a 45 hp hydraulic motor (with a displacement of 16.5 cubic inches/rev), would run at 540 rpm with 38.6 gpm at 2000 psi.

In a 100% efficient system, a 45 hp hydraulic motor would require a 45 hp PTO pump.

Formulas from: Hydraulic Motors, and Hydraulic Motors, courtesy of Villengineer.

Other useful information at Army Field Manual - Hydraulics.

 

[armyof1]

maybe someone can help me I have a hydraulic driven motor that was made to run a warner winch 6000lb it is new and cost over $500.00 what could I make with it to use with my tractor it has a gear on the end and is very heavy dutie I would hate for it to go to waste I do not know the hp or rpm but I would think it is slow could it drive a mower deck because I do not have a middle pto. I can take some pic if needed. Thanks

 

[Rowski]

Chris

Thanks for the links. I had forgotten all about the Army Hydraulic field manual, I remeber it now.

About what % loss can one expect, 5% to 10%?

Many thanks.

 

[DocHeb]

I can put numbers in, but don't have much practical experience. I will have to defer to somebody else.

 

[duane]

Derek,

At best a hydraulic pump's efficiency is 90%, and at best a hydraulic motor is 90%. That is a loss of 20%, or more realistically, 25% from your PTO to your attachment. The loss in energy shows up as mainly heat in the hydraulic fluid.

Duane

 

[rambler]

You also have loss in the hose, I've heard a typical pto pump & long hose & hyd motor more likely has 30-33% loss.

Now a well designed hydro on a tractor can have short lines, lots of oil cooling area, and a few million spent on R&D and they get in the 15-20% loss. Not going to happen with any length of rubber hose & quick disconnects & the like.

I would guess to put out 40 hp on the hydro motor shaft, you would need to be putting 65hp on the pto. I'm no expert tho. Oil restriction turns to heat, so I'll guess the pump needs to be sized bigger than the motor to make up those losses.

50-70 hp of hydraulic oil will take some serious hose size. /forums/images/graemlins/smile.gif I remember reading of a fellow who ran 3 large balers with a special hitch & 3 hyd motors. He used a 150 hp pump on the tractor pto (1000 rpm of course). Looked like quite a set-up, they did not offer many techincal details, but sure was interesting.

--->Paul