What hydraulic motor to buy?

schell2701 · Apr 16, 2012

Hello,

I am looking to add a hydraulic motor to replace the pto drive line on my Krone Swadro 900 hay rakes. Krone tells me it takes around 40 hp at 540 rpm's to operate the rakes. Would any body be able to tell me what hydraulic motor will be able to do this? Thanks!

WilcoKubota · Apr 16, 2012

Hello,

I think that there are people who can tell you what motor you should buy (I don't know), but my question, why would you change it to hydraulic driven instead of pto driven?

Thank you, Wilco.

schell2701 · Apr 16, 2012

We are going to start pulling our round balers behind the rake and need to utilize the pto drive line for the balers and still need to power the rake too.

WilcoKubota · Apr 16, 2012

Wow, that should become a big machine! :thumbsup:
Maybe you can post a vid if it's all working?
Succes whit it, I hope there are members who can tell you what sort of motor you should buy.

J_J · Apr 16, 2012

What kind of flow in GPM's do you have and what pressure is the relief valve set.

Your tractor develops only so much HP, to run itself and PTO HP. What one does not know is if the machine using the PTO is using all the PTO HP.

Question should be how much HP is required to run both machines.

One machine already uses 40 HP, so how much does the other machine require?

You say you are using 40 HP on the PTO. What is the rated PTO HP.

What is tractor HP? If it is at about 45 HP, then you are almost at your limit for HP.

oldnslo · Apr 16, 2012

To operate at 540 RPM you are probably looking at a LHST (Low Speed High Torque) since most motors don't run at that low RPM real well.

Figure approximate motor size.

40 HP = 390 ft-lbs torque = 4670 in-lbs torque

Fluid motor size formulae:

(torque (in-lbs) x 6.28) / PSI = Fluid motor displacement in cubic inches per revolution

(4670 x 628) / 2000 = 14.67 CIR

figure 15% efficient so 14.67 * 1.15 = 16.9 CIR

figure inlet GPM at 540 RPM (16.9 x 540) / 231 = 39.5 GPM

This is just a starting point since you will have to know your actual operating pressure less the line losses so your pressure to run the motor may actually be lower.

Input HP to the pump GPM * PSI / 1500 = 39.5 * 2500 / 1500 = 66 HP

I used 2500 PSI as your system operating pressure and figure you will have 500 PSI line loss.

What happened to the days of ground driven rakes???

Roy

J_J · Apr 16, 2012

Roy,

He is already using some or all of the HP for the other implement.

What we don't know is how much can be divided into the 40 HP. If one implement is using 20 HP, then only 20 HP is left to power the hyd motor on the other implement..

olde man · Apr 16, 2012

when you figure out your available hp&flow as jj suggested go to whitedriveproducts.com, use the dist. locator, they have several motors that will get you done at lower flows and moderate pressures. but you got a little homework to do. max tractor hp,minus hp required to drive the other piece of equip. then you need to know the available flow and pressure and hp

schell2701 · Apr 17, 2012

Hello,

Thanks everybody for the response. I just found out I gave some wrong info for my question! I need a motor that operates at 450rpm. I will be running one of the units on a JD 2955 (85pto hp) @21gpm and 2320psi. The other unit will be behind a JD 7410 (105 pto hp) @26gpm and 2900psi. Hope this info can help figure this out.