Posthole Digger PHD conversion to hydraulic??

[ss4010]

Hi All,

Since there is an impressive array of people on this site way more experienced than me with such matters, it seems appropriate to submit the following for your consideration.

I have been toying with the idea of converting my current Post Hole Digger from PTO driven to a hydraulic drive. Purchasing a Belltec or similar unit up front would make more sense but the current PHD I have was "free" with the tractor purchase. So the question is: sell the current unit (it has 20 or so holes) or try a conversion using a hydraulic motor coupled to my existing gearbox.

Essentially I have some steep hills and will need to drill uphill of my tractor, so a FEL mount makes sense.

There appear to be a few units out there similar to my vision. One example is the Land Pride HD25.

Land Pride HD25 Post Hole Diggers


So my current PHD is a Bobcat (re-branded Rhino?) and appears to have four 1/4" holes drilled and taped around where the PTO shaft couples to the gearbox. I'm thinking this might make it easy to attach a mounting flange, but may require larger bolts (drilling and tapping) to handle the torque. The gearbox is a 3.81:1 reduction.

The remotes on my Bobcat CT230 are rated at 7.9 gal/min and the relief is set for 2711 psi (if I'm not mistaken). Running that through

Hydraulic Motor Calculator

gives me 8.1 HP. If that is inadequate a PTO driven pump could be in the running for consideration.

Below are some pictures of my unit as it sits.

Essentially it seems that no more than 300 RPM would be required. Some things I'm not certain about are whether a relief in the motor will be required (or will the tractors relief valve be suitable for the remote). Will I need to increase the bolt size or will grade 8 1/4" bolts be acceptable (seems quite small to me).

The bolt spacing pattern on the existing PHD appears to be 2 5/8" square OC? or 3.625" in diameter? with the overall square portion being 3 1/2". The input shaft to the gear box is 1 1/4" diameter (shear bolt, no key) by 2 1/4" long.

I'm thinking a motor, motor mount, bucket mount and a coupling are the required components (beside hydraulic hose and fittings).

I'm a bit in the dark about the hydraulic motor mounts. It seems like a PEM-F is what would match up to the gear box.

Pump Motor Adapter/Dampening Flanges - Gas Engine Adapters by Vescor Corporation

It would seem surplus center has a mount that may work:

https://www.surpluscenter.com/item.asp?item=1-3238&catname=hydraulic


Has anyone else attempted such a conversion? Perhaps some of you have units like the Land Pride HD25 and can chime in on what hydraulic motor it uses and how it performs?

With the plethora of hydraulic motors out there any guidance would be appreciated. I'm not sure where to really begin with the range of variables out there. How important is the PSI rating on the motor? For example would I need to match the PSI rating on the motor to my relief valve pressure?

Would something like

https://www.surpluscenter.com/item.asp?item=9-7751&catname=hydraulic

be suitable with at 10-12 GPM rating at 1750 psi? My remote is rated for 7.9 GPM, so would that just mean the motor spins slower than the rated 460-540 RPM. I image the rated capacity of the remote is at max engine RPM's I would want to keep the tractor RPM's down so would that mean that something like

https://www.surpluscenter.com/item.asp?item=9-3516&catname=hydraulic

(3 ci 7 GPM max flow, 539 RPM)

would be more appropriate?

I'll stop rambling for now and look forward to comments and guidance.


Thanks,

Steve

 

[KWentling]

I converted a SpeeCo digger to hydraulic 10 years or so ago. I originally used it on the FEL but drilling holes straight (vertical) was a challenge due to the arc the loader travels in. Down pressure was the reason for doing it. About 5 years ago I got ambitious and built a frame that guides the head and has a hydraulic cylinder to provide the travel and down pressure (kind of like drilling rig). I run it with a 12 gpm (I think) PTO pump and it has a 15 gallon reservoir and a 2 spool valve. I made it to fit both the BX22 and a Category 2 3-point. I chain the mast to the drawbar so I can put the weight of the tractor on the auger. It works pretty good.
I made the hydraulic motor mount to bolt where the PTO guard was. They were metric bolts and either 8 or 10 mm. I coupled it up with a LoveJoy coupling. I had 2 CharLynn motors of different displacements. The first I tried ran it about the same speed as the PTO would but it didn't have enough torque to dig. I changed to the bigger displacement motor and although it is a little on the slow side it digs fine. All the materials except for the valve and hoses was stuff I had laying around or was pilfered from other projects. I can't tell you what the displacement of the motor is without looking or what the reduction of the head is. I think the relief on my valve was set to 1500 psi which was the rating of the motor.
I would drill and tap the holes out 3/8 or what ever the bolt hole size is on the adapter if you can. Can't say that the 1/4 wouldn't work but bigger is better. You'll also need to make sure the adapter is the right length face to face for your shaft lengths. I would look for a motor close to or more that the psi rating of the tractor so you will have the maximum torque. Not sure that the Surplus Center mount would be strong enough going by it's HP rating. It does resemble what I made though.
I'll try and get the displacement of the motor I used so you have something to go by. Might take me a day or two. Definitely a doable project.

Kim

 

[ss4010]

Hi Kim,

Pictures of your setup would be great. Without even starting it looks like mission creep may be setting in on my project. I'd also be interested in the size of the PTO pump you used.

My limit for newly purchased parts is $450 for this project (excluding mount and hoses). Any more than that and I will just buy a Belltec or similar.

Belltec Hydraulic Planetary Auger Drive 6-15 GPM, Model# NC150 | Auger Powerheads, Bits + Extensions | Northern Tool + Equipment

A motor mounting bracket could be fabricated out of 1/4" steel or such, should the cast al pre made brackets be too weak.


Thanks,


Steve

I converted a SpeeCo digger to hydraulic 10 years or so ago. I originally used it on the FEL but drilling holes straight (vertical) was a challenge due to the arc the loader travels in. Down pressure was the reason for doing it. About 5 years ago I got ambitious and built a frame that guides the head and has a hydraulic cylinder to provide the travel and down pressure (kind of like drilling rig). I run it with a 12 gpm (I think) PTO pump and it has a 15 gallon reservoir and a 2 spool valve. I made it to fit both the BX22 and a Category 2 3-point. I chain the mast to the drawbar so I can put the weight of the tractor on the auger. It works pretty good.
I made the hydraulic motor mount to bolt where the PTO guard was. They were metric bolts and either 8 or 10 mm. I coupled it up with a LoveJoy coupling. I had 2 CharLynn motors of different displacements. The first I tried ran it about the same speed as the PTO would but it didn't have enough torque to dig. I changed to the bigger displacement motor and although it is a little on the slow side it digs fine. All the materials except for the valve and hoses was stuff I had laying around or was pilfered from other projects. I can't tell you what the displacement of the motor is without looking or what the reduction of the head is. I think the relief on my valve was set to 1500 psi which was the rating of the motor.
I would drill and tap the holes out 3/8 or what ever the bolt hole size is on the adapter if you can. Can't say that the 1/4 wouldn't work but bigger is better. You'll also need to make sure the adapter is the right length face to face for your shaft lengths. I would look for a motor close to or more that the psi rating of the tractor so you will have the maximum torque. Not sure that the Surplus Center mount would be strong enough going by it's HP rating. It does resemble what I made though.
I'll try and get the displacement of the motor I used so you have something to go by. Might take me a day or two. Definitely a doable project.

Kim

 

[KWentling]

Hi Kim,

Pictures of your setup would be great. Without even starting it looks like mission creep may be setting in on my project. I'd also be interested in the size of the PTO pump you used.


Steve;
I'll see if I can get some pictures of it and figure out how to post them. This will be a first for me. The pump is a bit of a mystery because it came off an old Koyker loader. Thinking about it's probably less that 12 GPM, maybe only 8 or so. I'll see if I can come up with some info on it as well as the motor. Might be the weekend before you see anything.

Kim

 

[ss4010]

Just realized that I never added the pictures to the thread. Here are pictures of the PHD as it sits...

 

[KWentling]

Steve; The motor I used on the digger is a CharLynn 101-1008-07 which is a 20 cu/in. With any luck there will be pictures

 

[ss4010]

Steve; The motor I used on the digger is a CharLynn 101-1008-07 which is a 20 cu/in. With any luck there will be pictures

WOW... That is one serious sexy beast of a machine!! Thanks for the pics and the stats on the hydraulic motor. If I go that route, I will post pics of my contraption.

 

[KWentling]

WOW... That is one serious sexy beast of a machine!! Thanks for the pics and the stats on the hydraulic motor. If I go that route, I will post pics of my contraption.

I was kind of questioning the 20 cu./in. on that motor so I looked it up on CharLynn's site and it is actually 22.6 cu./in., 1250 PSI and 15 GPM max. I would think if you can find a higher PSI rated motor you could make do with a smaller cu./in. motor and get the RPM up. That was a motor I had and made work. Probably not the optimum motor. If I do have a 12 GPM pump I'm only turning the motor 122 RPM. I don't know what the reduction is on the digger head. Kind of need to know that. Should probably be looking at the in./lb. of torque number along with the gear reduction. I couldn't turn the auger to determine the reduction. I don't know your time frame for this project, but I do have some fencing to do yet this year but I'm currently building a garage. If I get the digger on a tractor I could check the ratio. Might not happen until fall. I had intentions of getting the thing painted but had a few mods I was going to do 1st, but never got around to it.

Kim

 

[KWentling]

I just went back to the motor site and the in./lb. of torque number is 3347. I wouldn't want less than that.

Kim

 

[lmalcomb]

Steve I don't think pointing you tractor up a steep hill and then applying down force with the loader sounds like a very safe thing to do. I am not sure how steep you are talking about when you say steep. I do think a loader mounted phd sounds sounds good for several obvious reasons.