Mid PTO speed

[MHarryE]

Most highly efficient piston pump for mobile equipment today is 92%. Pump and motor system is 92% x 92% = 85%. Gear pump and motor system 85% x 85% = 70%. These numbers don’t includes losses in valves, fittings, ant the losses go into heat. We figure 25% of hydraulic power needed to size hydraulic cooling system. Gears we figure 3% per gear set. Skid steers have a lot of hydraulic cooling capacity to compensate for the convenience of the hydraulic drive and of course how can you get a mechanical drive to the bucket end of a skid steer. Can’t beat the simplicity of a gear drive, one gear set to a mid mount PTO.

 

[Fallon]

Most highly efficient piston pump for mobile equipment today is 92%. Pump and motor system is 92% x 92% = 85%. Gear pump and motor system 85% x 85% = 70%. These numbers don’t includes losses in valves, fittings, ant the losses go into heat. We figure 25% of hydraulic power needed to size hydraulic cooling system. Gears we figure 3% per gear set. Skid steers have a lot of hydraulic cooling capacity to compensate for the convenience of the hydraulic drive and of course how can you get a mechanical drive to the bucket end of a skid steer. Can’t beat the simplicity of a gear drive, one gear set to a mid mount PTO.

Yup, more power, less fuel usage, more efficiency not to mention cheaper, generally with fewer parts. Hydraulics have much more routing options & generally a bit more control. But you cant beat a PTO shaft for impliments that use a significant portion of the machines HP

 

[dstig1]

So does anybody have any ideas of the torque or power that the Mid PTO is capable of? All the manual says is that it runs at 2000rpm whereas it gives PTO power for the rear 540 rpm PTO. Yes I know it varies by model, but I have no idea where to find that info for any model.

 

[Fallon]

So does anybody have any ideas of the torque or power that the Mid PTO is capable of? All the manual says is that it runs at 2000rpm whereas it gives PTO power for the rear 540 rpm PTO. Yes I know it varies by model, but I have no idea where to find that info for any model.

A mid-pto will output the same power as a rear PTO. Power = torque * RPM. If its spinning at 2,000rpm instead of 540, it has the same total power, just less torque. That goes for any machine.

(RPM * Torque in ft/lbs) / 5252 = HP. Not that the specific unit of power measurement changes the base principle.

 

[dstig1]

Thanks. Well yes, i get the math, but the question, I guess, is the input. Is it getting fed the same input as the rear PTO? If so, then I could agree that it has the same power, but I assumed given the tasks the Mid PTO is put to, that it is not up to the same specs. Do you know this to be the fact, or are you assuming? Not trying to be a jerk, just asking from where your response comes from.

 

[Fallon]

Thanks. Well yes, i get the math, but the question, I guess, is the input. Is it getting fed the same input as the rear PTO? If so, then I could agree that it has the same power, but I assumed given the tasks the Mid PTO is put to, that it is not up to the same specs. Do you know this to be the fact, or are you assuming? Not trying to be a jerk, just asking from where your response comes from.

Go back to the previous equations... If you double the RPM you half the torque. If you half the torque you can have lighter running gear to transmit the same power. In the case of a 2,000rpm mid PTO vs 540 rear, its transmitting just under a quarter of the torque.

It's the reason big tractors use a 1,000rpm PTO instead of 540. They can use lighter & cheaper running gear instead of what they would need to transmit the same torque at 540rpm.

 

[dstig1]

Well yes I get that, but as I asked, perhaps not clearly enough, was "is the input the same?" If it isn't, then the equations for the two PTOs are different. i don't know what happens inside the tractor to get to the PTOs...