Hydraulic Post Pounder

[kubotakid USA]

I think a better way to go would be using a hydraulic motor winding a cable much less oil to deal with, especially on the drop cycle, just thinkin outloud, Eric

 

[Redneck in training]

Variable torque hydraulic motor with a swash plate shouldn't require any oil flow when in neutral.

 

[johnlb]

Use a hydraulic motor and design the trip like a well drilling setup... just thinking outloud.

 

[BHD]

not sure if this would work or not, but if one used the standard valve to lift but near the cylinder, put in a Tee and a ball valve of the correct pressure ratting and dump the cylinder via the ball valve, using say a 3/4 return hose to the reservoir,

if there is additional restriction down hose on the return line one could dump it via the ball valve into the other port of the cylinder as well (thus acting like a reservoir for the ex caping oil) and then let the next charge stroke push the oil back to the tractor reservoir through the restrictions at a much slower rate,

 

[Putter]

This is in the "just so you know department" not being critical here, but in using the wire rope clamps, (yes I know that is not wire rope) the minimum number is 3 and the way to put them on is so that the "dead end" is adjacent to the U clamp not the saddle part of the clamp. as in the old saying "Do not saddle a dead horse" as a way to remember it. The top ones are correct (but need 3) the bottom ones are incorrect, I am not sure how well they will hold with the nylon rope, but probably OK. Again not trying to start anything, just passing along standard practice.

Learn something every day. Thanks k0ua :thumbsup:

As far as OP, the rig part of your build looks nice and clean, hope you get your hyd issue resolved. I think like others that a variable torque hydraulic motor with a swash plate would allow a free fall of the hammer. The design you based your build on? Does it use a hyd cylinder? If so maybe see what they do differently. Good luck.

 

[zonta223]

I think most people are missing what the OP wants.....to be able to cycle 30 or 40 strokes a min.....he has a lot of posts to drive and a hydraulic motor/and or latch system would be way to slow... Used a few post knockers myself in the vineyard and had a couple of problems like this. The cure seemed to be to always made sure the return line was of a large size that went directly back to the hydraulic tank.

regards

 

[kubotakid USA]

I looked up the vector site a watched the video, Looks very fast only took 3 hits to set the post, dont see the need for 30/40 hits a minite, the key is droping a lota weight fast, the op has done a great job of copying the vector machine, figuring out the restrection is going to take more than a big *** return line he also needs a big *** valve, 3/4 / 1in ports, another thing that will need to be LARGE is the port coming out of the cylinder, dont matter how big the line/valve are, IF the oil cant get out of the cylinder, i think he said hes using a 2in bore cylinder, it probably has a 1/4 / 3/8 port, that should be 3/4 plus, not a big deal to bore the port and weld in a large one, imho Eric

 

[mjncad]

First let me compliment you on your fabrication skills, and once you get it operating the way you want, I hope you paint it.

Another factor adding resistance is the seals and glands in the hydraulic cylinder. I agree with others saying you need a big unrestricted return oil line to dump the fluid back to the tank.

However; other comments about using a hydraulic motor and pawl or latch system would probably be quicker.

A few years back I had some soil samples and perc tests done, and the guy doing it had a beat to crap F-350 with what looked like a homebuilt drill and pounding rig. When he wasn't drilling, he was pounding and used the rope on the winch's cathead to control the weight's lift rate. This rig looked like an accident waiting to happen; but it got the job done. Maybe the following photos will give you some ideas.

 

[MNBobcat]

Did you ever get it working the way you wanted it to?

 

[RickB]

I looked up the vector site a watched the video, Looks very fast only took 3 hits to set the post, dont see the need for 30/40 hits a minite, the key is droping a lota weight fast, the op has done a great job of copying the vector machine, figuring out the restrection is going to take more than a big *** return line he also needs a big *** valve, 3/4 / 1in ports, another thing that will need to be LARGE is the port coming out of the cylinder, dont matter how big the line/valve are, IF the oil cant get out of the cylinder, i think he said hes using a 2in bore cylinder, it probably has a 1/4 / 3/8 port, that should be 3/4 plus, not a big deal to bore the port and weld in a large one, imho Eric

The obvious solution is to source an operating valve directly from a post driver manufacturer and match the hoses and fittings to those used in similar machines.