Hydraulic post hole digger idea

Howdy all. Not having much more than a rudimentary knowelge of hydraulics, I figure I will ask this here. I have an old ford cl45 skid steer that I am going to scrap out. I was wondering if one of the wheel drive hyd motors could be used to make a post hole digger and have it work off the aux of my bobcat 763 with 16 gpm rating. My thought is if its strong enough to power the wheels then it should be strong enough to turn an auger? I know the wheels are driven off a different pump than the aux.(at least on that ford) which might make it non compatible?
If someone knows this wont work you could spare me the time and effort of trying to cobble one up.
Or if you think it might work and have tips or suggestions about the project that would be great also. Thanks guys,,, Jerry

It should work. (I never built one) But the concept is the same.

Rotary hydraulic motor mounted to a fixture. With 2 pressure lines, inlet/return. Speed may be an issue, it might be too fast at full open. I have seen a little bit of skid steer hydraulics. you might have a 5/8" port on the skid steer, my neighbors Deere skid steer has 5/8" ports. Remember that hyd. pressure gives force and flow gives speed.

I build one last fall,I can shoot you a pic or 2 if you'r interested,might give you an idea of how to build it.
I posted a pic a while ago on the implement forum but cant find it.

Thanks for replies guys. Yes Bison I would appreaciate a couple of pics . I will send you an email with my addy.
Any more thoughts are welcome.. thanks Jerry

Should work. I've spent a lot of time trying to design one. Thanks Bison for the pics. You might be a little bit better fabricator than me though.

As long as your 763 with 16 gpm system doesn't have a higher pressure than what your motor has but I would imagine it will work. Otherwise you may want a psi relief valve or hope the psi doesn't blow out the seals in the motor. Lesser of a problem would be if the motor can handle the gpms. That can be fixed with a flow divider or see how long it will last. For occasional hole digging probably not a problem. Running 24/7 maybe.

Just remember the higher the psi you put on the motor and the higher the displacement, the more power/torque it will have. The higher the gpm you run through a motor, the faster it will spin. Typically a hanging auger will spin fairly fast and as you put it in the ground and start digging it slows down. I've seen power company telephone pole augers turn so slow I can count the revs. 20 to 200 rpm will work ok.

Have a 2 way valve so you can reverse direction on the motor in case you drill it into the ground and want to reverse it out.

I've looked at a lot of the commercial ones and rented some and it doesn't really take a lot of power. Course some use gear reduction drives.(like a 10hp honda engine and attached pump drove an auger for all I wanted in gumbo clay with no problem)

TSC sell a 3 point auger with a 2.73 gear reduction. At 540 pto rpm, you get about 198 rpm.
That is assuming you are running it wide open to get full pto rpm. At half speed, you get about 100 rpm out of the auger.

What I'd like to invent is some type of 3 point mount that will allow the auger to stay vertical without moving the tractor as you drill down. A stationary tractor while drilling a hole will leave you with a crooked hole as the 3 point support arm comes down to ground level which pushes the motor backward. Maybe it's not a problem once you get the knack of it and move forward as you drill.

Finally if you cobble up an auger and it doesn't work, you can always change to another motor. Don't have my notes here but typical motors I've been looking at to go with my 2606 with 17 gpm pump at 2000 psi have a 1" shaft and 3/4" hoses. There are 2 or 3 different universal motor mounts/bolt patterns that the motors have. A couple hundred bucks. Probably have enough torque to drill water wells with (which is in the back of my mind which would be easier than back when I worked on a cable tool rig). Just hate to buy too light of a motor and then find it doesn't work well.

Go to surpluscenter.com and bailleynet.com to find the specs on your motor or a similar one. They mention certain motors as being used on skid steer drives.

Good luck and post back with diagram and pics of what you build.

Thanks for the info. I guess I will give her a go. Looks like I might need a flow control valve. was wondering if just one would work or do I need one on each line since it will have reverse flow?

Thanks for the pics, looks like a nioe unit. Jerry

I believe you would plumb the flow control valve in before the 2 way valve that your 2 hoses would connect to with quick disconnects. On your two way valve, 1 is forward, middle is neutral, and the second one is reverse, you can get a spring detent to return it to neutral. This is a safety feature that makes you hold the valve open all the time while drilling and particularly good if you got a worker on the ground cleaning the hole with a shovel. The spring detent is basically a dead man control. Without it you might also be tempted to exit the machine with it running to shovel some dirt or something and then the hanging string on your sweatshirt hood gets blown into the auger and then your face gets augered away.

Hello Jerry; I bulit one yrs ago. I used a Ross Hyd, motor, it was
off a street sweeper. It run the gutter broom. Used 1/4 flat stock
and made a box to enclose the motor. Welded two short 1" inside
dia. pipe to the top of the box. This was pinned to a 3pt boom.
Drilled a LOT of holes with this. After I got a Bobcat......Whoa! Now
you can look forward, and you have" reverse"......Last yr we did
60a of fence.....Works grt!! Good Luck on yours Bobmn

Robert: Got any pics and specs on the motor? Thanks.