Hydraulic PTO

I am trying to ready my machine to take 3 pt hitch implements, auger, rotary mower etc. I found a 3 pt hitch mount with a universal attach plate for 400 bucks. I am now in the process of attempting to convert a 1 inch key shaft axle on my hydraulic motor to drive a 6 spline 1"3/8 pto...I have had no luck finding any sort of cross over adapter so I am attempting to weld a shaft off another adaptor to some fittings etc to convert it to the 1 inch keyed shaft... if this makes any sense?? Has anyone done this before, successfully or failed. I am curious to know if this is gonna work or if I am in for a huge pooch screw. thanks

Surplus center has this https://surpluscenter.com/item.asp?UID=2009042714302629&item=1-2242&catname= but none that are 1 inch.
Could you bush your saft up to 1.25"?
Ken

skidsteer.ca said:

Surplus center has this https://surpluscenter.com/item.asp?UID=2009042714302629&item=1-2242&catname= but none that are 1 inch.
Could you bush your saft up to 1.25"?
Ken

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Thats similar to what I cut apart to get the 6 spline portion. Mine went from the 6 spl 1 3/8 male adapted to a 6 spl 1 1/8 female. Thats the first one I have seen that was adapted to fit a keyed shaft though. At least I know its an option if I screw up what I am working on. Thanks for the heads up Ken.

coreya3212 said:

Thats similar to what I cut apart to get the 6 spline portion. Mine went from the 6 spl 1 3/8 male adapted to a 6 spl 1 1/8 female. Thats the first one I have seen that was adapted to fit a keyed shaft though. At least I know its an option if I screw up what I am working on. Thanks for the heads up Ken.

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So i cut that adaptor like i said. Then my neighbour comes the next day with a hyd motor that the shaft is 1 1/8 6 spline. so i grab a new adaptor but there is no hole in the shaft on the hyd motor so you can pin the adaptor onto the shaft. So I will just drilla hole in the shaft....right. The shafts on these things are made of diamonds I think. I coulnt even scratch it. So i used my welded up hunk of crap adaptor to the original motor. It worked like a charm on the one test hole i dug.

So what I have now is a 3 pt hitch plate for the bobcat with a pto and am wondering if it will drive my rough cut mower for weeds int he ditches etc....we shal see.

coreya3212 said:

So i cut that adaptor like i said. Then my neighbour comes the next day with a hyd motor that the shaft is 1 1/8 6 spline. so i grab a new adaptor but there is no hole in the shaft on the hyd motor so you can pin the adaptor onto the shaft. So I will just drilla hole in the shaft....right. The shafts on these things are made of diamonds I think. I coulnt even scratch it. So i used my welded up hunk of crap adaptor to the original motor. It worked like a charm on the one test hole i dug.

So what I have now is a 3 pt hitch plate for the bobcat with a pto and am wondering if it will drive my rough cut mower for weeds int he ditches etc....we shal see.

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It will, you will find mowing heavy grass saps your rpm more then brush though.
Ken

skidsteer.ca said:

It will, you will find mowing heavy grass saps your rpm more then brush though.
Ken

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My old neighbour doesnt think it will drive a mower due to lack of torque??? I sort of thought that once you get it going, it has some of its own inertia to drive it through. All i can do is give it a go. Will let you know. Thanks.

coreya3212 said:

My old neighbour doesnt think it will drive a mower due to lack of torque??? I sort of thought that once you get it going, it has some of its own inertia to drive it through. All i can do is give it a go. Will let you know. Thanks.

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Torque is a factor of your pumps flow and pressure, and the cubic inch volume of the motor you choose for your hyd pto. 16.9 gpm at 3000 psi on my cutter gives me 27 hp to drive the mower, it works pretty darn good. Obviously a high flow machine pumping 30 to 40 gpm at 3000 would give a lot more power, but it is relative to your needs. I can start into a bush with 2 to 3" diamond willow and do more damage to it then 6 guys with power saws and brush saws could in a hour.
It won't be like a tractor where you have full engine hp to the pto shaft, but I think you will be surprised how aggressive it is just the same. Also what it lacks in brute hp will save you time in breakdowns that don't occure, no broken shear pins, busted gear box gears etc
I had run mine a bit on a 553 with 8 gpm and 2000 psi, the cutter only turned 270 rpm instead of 540 because of the small pump, and it would still kick my 17 hp jd lawn tractors butt in grass.
Ken

skidsteer.ca said:

Torque is a factor of your pumps flow and pressure, and the cubic inch volume of the motor you choose for your hyd pto. 16.9 gpm at 3000 psi on my cutter gives me 27 hp to drive the mower, it works pretty darn good. Obviously a high flow machine pumping 30 to 40 gpm at 3000 would give a lot more power, but it is relative to your needs. I can start into a bush with 2 to 3" diamond willow and do more damage to it then 6 guys with power saws and brush saws could in a hour.
It won't be like a tractor where you have full engine hp to the pto shaft, but I think you will be surprised how aggressive it is just the same. Also what it lacks in brute hp will save you time in breakdowns that don't occure, no broken shear pins, busted gear box gears etc
I had run mine a bit on a 553 with 8 gpm and 2000 psi, the cutter only turned 270 rpm instead of 540 because of the small pump, and it would still kick my 17 hp jd lawn tractors butt in grass.
Ken

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My Aux hyd are not hi flo. I cant remember the psi but they run at 12 GPM i think. I dont know the motor specs either. Pieced this together out of the junk pile. The hyd motor at full throttle put out 650-700 rpm so I checked my tractor pto and it ran at the same speed almost exactly even though its supposed to be 540 pto. I assume it is and the guage is a little kitiwonkus, but never the less, I believe them to be turning at the same speed. Once I get off my lazy arse and hook it up, I will let you know how I make out.

PS- I was also thinking what you confirm, that the hyd motor is as strong as the fluid and pressure driving it. I didnt know about CC volume it displaces factoring in but that makes sense. Thanks Ken.

coreya3212 said:

My Aux hyd are not hi flo. I cant remember the psi but they run at 12 GPM i think. I dont know the motor specs either. Pieced this together out of the junk pile. The hyd motor at full throttle put out 650-700 rpm so I checked my tractor pto and it ran at the same speed almost exactly even though its supposed to be 540 pto. I assume it is and the guage is a little kitiwonkus, but never the less, I believe them to be turning at the same speed. Once I get off my lazy arse and hook it up, I will let you know how I make out.

PS- I was also thinking what you confirm, that the hyd motor is as strong as the fluid and pressure driving it. I didnt know about CC volume it displaces factoring in but that makes sense. Thanks Ken.

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In my attempt to stave off boredom, I have been reading old threads. Ken, in discussion on pto driven mowers, you mention on one that you burnt out a motor, and then installed a bypass loop so the motor could free wheel with the cutting blades as they slow down once you stop the hydraulic flow... can you explain how this was done? I asked my neighbour that question and he figured it would not be a issue, but sounds like that may not be the case.

coreya3212 said:

In my attempt to stave off boredom, I have been reading old threads. Ken, in discussion on pto driven mowers, you mention on one that you burnt out a motor, and then installed a bypass loop so the motor could free wheel with the cutting blades as they slow down once you stop the hydraulic flow... can you explain how this was done? I asked my neighbour that question and he figured it would not be a issue, but sounds like that may not be the case.

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From memory its plumbed across the hydraulic lines. Essentially the throry was when you have a blade weighing say 20kg spinning at 600 RPM you have a LOT of potential energy there. This is great for mowing as you hit a larger sapling and it will simply cut through it, but when you turn your aux hydraulics off it basically dead ends the hydraulic lines, so the motor will want to keep spinning with the weight of the blade. This will cause pressure spikes in the lines and motor, this potentially can blow seals or cause damage to the internals of the motor. You will find when you rotate a motor by hand, they become a crude hydraulic pump, thats why you get pressure spikes.

Tazza said:

From memory its plumbed across the hydraulic lines. Essentially the throry was when you have a blade weighing say 20kg spinning at 600 RPM you have a LOT of potential energy there. This is great for mowing as you hit a larger sapling and it will simply cut through it, but when you turn your aux hydraulics off it basically dead ends the hydraulic lines, so the motor will want to keep spinning with the weight of the blade. This will cause pressure spikes in the lines and motor, this potentially can blow seals or cause damage to the internals of the motor. You will find when you rotate a motor by hand, they become a crude hydraulic pump, thats why you get pressure spikes.

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To clarify a bit.
When you stop the flow, the inertia of the spinning blades turn the hyd motor into a pump. It generates pressure in the return line to the loader. Both the lines to the loader are blocked so the oil can't go there once you shut off the flow.
I just T'd a line in between the pressure and return hose so the return line pressures goes back to the inlet side of the hyd motor.
You must however also add a 1 way flow valve known as a "check valve" so when the loader is pumping the oil the check prevents it from going through the bypass line and forces the flow through the cutter motor.
Now if you use this on your auger you will not be able to reverse the bit, unless you add a shutoff valve to the bypass loop.
A 1/2" check is available from surplus center for about 25 and and a shut off valve is 40 to 50.
Ken

skidsteer.ca said:

To clarify a bit.
When you stop the flow, the inertia of the spinning blades turn the hyd motor into a pump. It generates pressure in the return line to the loader. Both the lines to the loader are blocked so the oil can't go there once you shut off the flow.
I just T'd a line in between the pressure and return hose so the return line pressures goes back to the inlet side of the hyd motor.
You must however also add a 1 way flow valve known as a "check valve" so when the loader is pumping the oil the check prevents it from going through the bypass line and forces the flow through the cutter motor.
Now if you use this on your auger you will not be able to reverse the bit, unless you add a shutoff valve to the bypass loop.
A 1/2" check is available from surplus center for about 25 and and a shut off valve is 40 to 50.
Ken

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Ahhh. That makes sense. So if I nderstand, the motor turning is like running a pump with no oil circulating and burn it out? That makes sense.

coreya3212 said:

Ahhh. That makes sense. So if I nderstand, the motor turning is like running a pump with no oil circulating and burn it out? That makes sense.

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When the flow stops the motor wants to keep spinning from the inertia of the blade. Its like running your lawn mower. You run it flat out and smack it into a stump and it stops instantly, the instant stop can break the crank shaft. Your hydraulic motor will be doing the same, it is full of oil so it won't burn out as such, but the shock of stooping instantly can cause internal damage.
Does that make sense?

Tazza said:

When the flow stops the motor wants to keep spinning from the inertia of the blade. Its like running your lawn mower. You run it flat out and smack it into a stump and it stops instantly, the instant stop can break the crank shaft. Your hydraulic motor will be doing the same, it is full of oil so it won't burn out as such, but the shock of stooping instantly can cause internal damage.
Does that make sense?

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Doesnt really make sense to me. Thanks for trying fellas. I understand hyd to about the extent that I know oil under pressure forces things around and thats about it. I would need to open a hyd pump and see the insides to understand it I think. Southern Albertans are a tad thick...ha.

coreya3212 said:

Doesnt really make sense to me. Thanks for trying fellas. I understand hyd to about the extent that I know oil under pressure forces things around and thats about it. I would need to open a hyd pump and see the insides to understand it I think. Southern Albertans are a tad thick...ha.

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lol not thick at all.
Think of it this way, when the hydraulic supply is shut off the oil can't flow as its blocked at the pump end. The lines and motor are still full of oil, oil or any other liquid can not be compressed so there is no buffering as such, the only give there is in a hydraulic system is the tube lines and hoses, these flex ever so slightly. When a motor is full of oil its essentially hydraulically locked, again oil can not be compressed so when the supply is shut off the motor can not free wheel to slow down slowly on its own. It will be forced to stop instantly, with a load attached the forces on the internals of the pump can be enormous as they want to keep rotating. At no time is the inside of the pump run dry, its just made to stop much faster than it actually should.
To prove the fact on a hydraulically locked motor, with the machine turned off and the motor to the cutting deck full of oil, try turning the blade. It will move slightly and slowly but it won't move much and require a lot of force. This is the oil resisting turning, this is what it will do every time you shut the oil supply off. The faster the blades turn the more force will be on the motor when you shut it off.
Is that any better at all?

Tazza said:

lol not thick at all.
Think of it this way, when the hydraulic supply is shut off the oil can't flow as its blocked at the pump end. The lines and motor are still full of oil, oil or any other liquid can not be compressed so there is no buffering as such, the only give there is in a hydraulic system is the tube lines and hoses, these flex ever so slightly. When a motor is full of oil its essentially hydraulically locked, again oil can not be compressed so when the supply is shut off the motor can not free wheel to slow down slowly on its own. It will be forced to stop instantly, with a load attached the forces on the internals of the pump can be enormous as they want to keep rotating. At no time is the inside of the pump run dry, its just made to stop much faster than it actually should.
To prove the fact on a hydraulically locked motor, with the machine turned off and the motor to the cutting deck full of oil, try turning the blade. It will move slightly and slowly but it won't move much and require a lot of force. This is the oil resisting turning, this is what it will do every time you shut the oil supply off. The faster the blades turn the more force will be on the motor when you shut it off.
Is that any better at all?

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If you contact princess auto or surplus center and ask to speak to a hydraulic tech about the difference between a motor valve (which is what should be used in the hyd pto case) versus a cylinder valve (which is the type all skidsteers have) they should be able to enlighten you.
If you used a motor valve to control a cylinder it would not hold the cylinder in position as both hoses are looped together (inside the valve) when the handle is in neutral. But a cylinder valve is designed to hold the cylinder in position by not letting the the oil from one work port to the other. When you use a cylinder valve on a motor, it works fine until the the handle is put to neutral, then the motor is force to stopped instantly.
Ken

skidsteer.ca said:

If you contact princess auto or surplus center and ask to speak to a hydraulic tech about the difference between a motor valve (which is what should be used in the hyd pto case) versus a cylinder valve (which is the type all skidsteers have) they should be able to enlighten you.
If you used a motor valve to control a cylinder it would not hold the cylinder in position as both hoses are looped together (inside the valve) when the handle is in neutral. But a cylinder valve is designed to hold the cylinder in position by not letting the the oil from one work port to the other. When you use a cylinder valve on a motor, it works fine until the the handle is put to neutral, then the motor is force to stopped instantly.
Ken

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Taz, Ken, thanks fellas. Its starting to make a little sense. I will talk to the hyd guy at Princess auto and see what they can do to help me out. I have used my auger and it seems to work good but when I shut off the flow, the auger doesnt even want to keep pushing back cause they are geared so much lower than a mower. I also just got a steal of a deal on a 3 pt cement mixer which will work as well the same way I think, being gears to spin slow compared to the pto.

coreya3212 said:

Taz, Ken, thanks fellas. Its starting to make a little sense. I will talk to the hyd guy at Princess auto and see what they can do to help me out. I have used my auger and it seems to work good but when I shut off the flow, the auger doesnt even want to keep pushing back cause they are geared so much lower than a mower. I also just got a steal of a deal on a 3 pt cement mixer which will work as well the same way I think, being gears to spin slow compared to the pto.

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Just as an update. The cement mixer was modified. I took a tooth gear and welded it to a bushign to fit on its own hydraulic motor and it seems to work good although I havent actually mixed and concrete yet.

Ken, The mower is up and running without the bypass loop and seems to cut like a bugger like you said it would. Knocked the weeds down in a hurry. I do need to flange up some wheels on it though as it is a fairly bouncy and un even cut. I idle the machine down to slow the mower before disengaging the aux flow to minimize the abuse to the motor and will see how this goes. Motor was only 70 bucks so if I wreck it, live and learn.

I did blow one up already but what happened wa sthe mount plate was only secured at the top and the torsion from engaing the mower bent the plate, which cracked the motor plate which shot hyd oil a long way. Luckily not in my face. I made a new plate bigger and welded it solidly and seems to work so far.

Thanks All. Good luck with your projects!!!

coreya3212 said:

Just as an update. The cement mixer was modified. I took a tooth gear and welded it to a bushign to fit on its own hydraulic motor and it seems to work good although I havent actually mixed and concrete yet.

Ken, The mower is up and running without the bypass loop and seems to cut like a bugger like you said it would. Knocked the weeds down in a hurry. I do need to flange up some wheels on it though as it is a fairly bouncy and un even cut. I idle the machine down to slow the mower before disengaging the aux flow to minimize the abuse to the motor and will see how this goes. Motor was only 70 bucks so if I wreck it, live and learn.

I did blow one up already but what happened wa sthe mount plate was only secured at the top and the torsion from engaing the mower bent the plate, which cracked the motor plate which shot hyd oil a long way. Luckily not in my face. I made a new plate bigger and welded it solidly and seems to work so far.

Thanks All. Good luck with your projects!!!

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Thats kinda the hazards of do it yourself. You learn where it could have been better. Mind you, that can be the hazards of buying new too, sometimes made just good enough to make it through warranty.
Add the bypass. The cutter also really slows down when you lift the arms of the loader, as the arms get the oil instead of the motor, and being able to coast in this situation would be beneficial also. Think the check valve was $10 with hoses and T's still under $40
I find the front wheel good if the mowing is a smoother field, but if its too rough the front wheel stubs into the holes (not as tall as the skidsteer wheel, so won't climb up and over as much) and has been broke off many times.
When I put mine back on (yet again) it is going into a 2" receiver, so it can be easily removed when the mowing is too rough. (we mow some logging cut overs for atv/sled trails for hunters) and its pretty easy to bang and bend the deck up in amongst the stumps and rocks. I completely gave up renting the brusher for this application. No matter how tough I made the thing it had a 50% chance of coming home broken.
This spring I cut the front out of the deck this year exposing 6" s of the blade tips, throws debris a little more. But much less bb prone to running out of power in tall grass as it discharges @ 50% of the grass.
Ken