Home-Built Hydraulic Post Pounder; Speeding up the freefall

[KubotaCrossing]

I am truly humbled by the patient and thoughtful responses. Thank you all for sharing your thoughts, experiences and ideas. I really appreciate you!

I'm going to followup shortly with perhaps a few "plumbing" diagrams to illustrate the current setup and some of the ideas proposed. It will definitely be edifying for me but maybe it will also help the next person that comes along trying to do something similar.

Thanks again!

 

[Rustyiron]

Bitterroot Valley- ahhhhhh. Love that area, especially the steak house (Dicks?) on the road to Lolo hot springs. :thumbsup:

 

[CobyRupert]

The return port should be 3/4 and dump back to the tractors hyd fill cap..

This, and Tinhack’s comment on the breather size.
....but oil still has to flow back through the spool valve (with anti-drop load checks??) on the unit. How fast it can do that might also be key. Or like wdchyd and OldAndTired refer to, bypass spool valve for return flow with something else.

 

[KubotaCrossing]

Okay. I thought I'd do a few drawing to show how this thing is currently plumbed. Also throwing in a couple of revisions.

I know I'll need to acquire a few more pieces and parts so drawing it out helps in detailing what I need. I love living in "fly-over" country but getting parts can be a challenge. Sometimes I feel like that guy in the movie "O'Brother" whose told that it will take two weeks to get a new transmission belt for his Model T - "This place is a gol-dang geographic oddity, two weeks from anywhere!".

Here's a simplified picture of the current plumbing. It works, kindof. The weight goes up, somewhat slowly. The weight comes down WAY TOO SLOW:


Several contributors have suggested that the problem is that the hydraulic fluid flow is being unduly restricted. The spool valve has a 3/4" work port. I'm currently reducing that down to 1/2" hose, then finally the port on the cylinder is only 3/8".

So let's first look at enlarging the cylinder work port to at least 3/4" and then increasing the working hose to that size:

Pros:
o I can control up/down with the single spool valve
o Only need to change one hose
Cons:
o I'm constrained by the internal porting of the spool valve, whatever that may be
o May introduce excessive heat to the spool valve


I noticed that the cylinder actually has two 3/8" work ports on the non-rod end. Here's a scenario where we enlarge that second work port to 3/4" and add a 3/4" ball valve, leaving the plumbing for the first work port intact:

Pros:
o The first work port plumbing isn't being changed, so the "up" speed will remain predicable
o The ball valve allows for a quick dump of the hydraulic fluid back to tank. In theory this should make the weight drop twice as fast
o Bypassing the spool valve for the down stroke should extend the life of the valve as well as avoiding any internal restrictions
o The spool valve can still be used for a slow controlled up and down. This would is useful for positioning and locking the pounder for road travel
Cons:
o Driving posts requires the coordination of manipulation too separate valves
o Cost of ball valve and extra hoses


And then finally an option that again involves increasing the work port and hoses to 3/4" but adding a tee inline:

Pros:
o The first work port plumbing IS being changed, so the "up" speed MIGHT be faster
o The ball valve allows for a quick dump of the hydraulic fluid back to tank. In theory this should make the weight drop twice as fast
o Bypassing the spool valve for the down stroke should extend the life of the valve as well as avoiding any internal restrictions
o The spool valve can still be used for a slow controlled up and down. This would be useful for positioning and locking the pounder for road travel
Cons:
o The first work port plumbing IS being changed, so the "up" speed MIGHT be slower
o Driving posts requires the coordination of manipulation too separate valves
o Cost of ball valve, tee and extra hoses

I have a new found respect for the folks that design these systems. There's a lot to think about.

Thoughts on the revisions?

 

[Birdhunter1]

You are making this very much harder than it needs to be. To make it simple you need a constant supply to a log splitter valve on the driver than has an open center that fluid will pass through when not directing fluid to or receiving from the cylinder that raises your driver up. The return hose from that has to go to the tank on your tractor, the easiest place is to the same hole in the transmission you pour hydraulic oil into. The log splitter valve needs 1 hose going to the cylinder that makes the driver go up... it will send fluid to it when you move the valve control one way and it will come back through the same hose and out the return when you move it the other way.

One handle up/down.

On my Shaver HD8 when I pull the handle towards me it raises, when I slam it forward it drops. Its very simple and easy, 1 valve and a total of 3 hoses (1 from the tractor, 1 to the cylinder, one to the tractor. Technically two valves, I will be using the remote spool valve on the tractor with a bungee cord holding it to full constant flow, one hose will be coming from that remote on the back of the tractor to the driver, the flow will be returning to the sump of the tractor.

 

[KubotaCrossing]

You are making this very much harder than it needs to be. To make it simple you need a constant supply to a log splitter valve on the driver than has an open center that fluid will pass through when not directing fluid to or receiving from the cylinder that raises your driver up. The return hose from that has to go to the tank on your tractor, the easiest place is to the same hole in the transmission you pour hydraulic oil into. The log splitter valve needs 1 hose going to the cylinder that makes the driver go up... it will send fluid to it when you move the valve control one way and it will come back through the same hose and out the return when you move it the other way.

One handle up/down.

On my Shaver HD8 when I pull the handle towards me it raises, when I slam it forward it drops. Its very simple and easy, 1 valve and a total of 3 hoses (1 from the tractor, 1 to the cylinder, one to the tractor. Technically two valves, I will be using the remote spool valve on the tractor with a bungee cord holding it to full constant flow, one hose will be coming from that remote on the back of the tractor to the driver, the flow will be returning to the sump of the tractor.

You are so right my friend. In concept it is SO simple.

In practice the devil is in the details.

 

[Birdhunter1]

I made a video on a dry erase board with a very crude drawing and video.
Shaver post driver hookup drawing - YouTube

 

[KubotaCrossing]

I made a video on a dry erase board with a very crude drawing, (DISCLAIMER) I don't intend to sound rude or liking I'm talking down to you just the way I normally talk, I have been told that often but I'm a nice guy really, most of the time.
January 9, 221 - YouTube

Rick,

No, gosh no. I saw no offence intended nor take any offence. I think you are a really nice guy especially what with you taking the time to film and layout your thoughts. Yep I get what you are saying.

I've looked at those Shaver PPs. Wish I had one. I notice that they use hydraulics exactly as you stated but they don't use a conventional hydraulic cylinder. The "cylinder" is actually a triangular tube sized just so, with plate/plunger. The hoses are right sized for the job as is the valve, weights, springs, etc. The "cylinder" is designed to use a minimum of fluid. The valve is designed to fast fast evacuate. The point is, somebody sat down and engineered the whole thing.

If you look at my drawings, I'm "plumbing" mine essentially the same way Shaver plumbs theirs. Difference of course is I'm winging it. I'm limited to off-the-shelf parts. Only after trial and error discovered that I under-sized ports, hoses, etc.

So am just trying to get thoughts on plumbing pieces and parts at this point.

Thanks again for your help!
Ed

 

[Birdhunter1]

My previous tractor, Ford 3910 and a 10" power pole I drove in the dirt. The drivers work best in moist soil, a rule of thumb I always went by was if I could drive the tractor on it without getting stuck then I could drive a post solid. Later of course I proved beyond that and laid a corduroy path of old timbers down to get a few posts in and they were solid to.

A post the size of the one in this photo took me less than 5 minutes to get in the dirt 3' deep from the time of getting off the tractor to the time I got back on it. No boring of a pilot hole (though that helps with big posts) and I can't remember if I cut a wedge on that one or not.

 

[Birdhunter1]

I've seen an accumulator setup on a Shaver that a guy who used to be a distributor marketed and sold which would allow you to use the remotes and not have to pipe directly back to the sump. That guy and Shaver had a falling out of some sorts and I have not the accumulator on any Shaver information. Maybe the guy who was the distributor built it himself and it wasn't a Shaver item, either way it was a slick looking setup and appeared to be alot more user friendly.

I did scratch that video first video I made and then did a new one, it might follow better than the first. The point it that if you are returning through a remote it is too much of a restriction, I still haven't figured out what the 4th hose in your photos does but I'm betting if you eliminate it and pipe to the sump your troubles will go away.

**** And get that thing out of your garage to test it. If it drops correctly it will bust your floor and send a crack every direction. My dad was working on this one in his garage back in 1975 (before i was born) and the cracks are still there..... brand new slick floor at the time and BAM!