Post Hole Digger (PHD) Hydraulic Down Pressure (HDP) Questions.

[npalen]

Thinking about adding HDP to my PHD and wondering about a couple issues. I see that all the HDP kits use a single acting cylinder with a return line to tank and this obviously works fine. But I would like to make up my own HDP using my top link double acting cylinder and trying to figure out why this wouldn't work. The cylinder would be mounted to the PHD much the same as the store-bought units using the lost motion link but both hoses would be to the directional control valve (DCV) on the tractor. It looks to be important that any of the HPD cylinders must not be activated unless the 3PH position lever is fully down. Would that be true regardless of whether the HDP cylinder is single or double acting?

I will attach a picture below from this post to help visualize how the Hydraulic Down Pressure works. http://www.tractorbynet.com/forums/attachments/157712-help-me-understand-downforce.html



Edit: After some more thought, it would seem that to utilize the double acting cylinder without damage, the 3PH position control lever would have to be left in the full down position at all times and then operate the HDP cylinder to raise and lower the PHD. Does that make sense?

 

[MtnViewRanch]

You are doing this so you can save on the cost of a hydraulic?:confused3: You are going to have to do some serious engineering to get this to work without problems. This is not to say that it can not be done, but why bother? Before it's all said and done, you may very well end up spending $10 to save a buck. Buy the HDP kit, drill some holes and be happy.



Good luck with your endeavor.

 

[npalen]

Brian, that would be way too easy. You challenged me and that's all I need to proceed.
It seems a shame after buying the top cylinder from you, which works great by the way, to not be able to use it with the PHD. I did a little work with the PHD today and observed the angle change between the inverted-U piece that attaches to the lower lift arms and the main beam when the PHD is raised and lowered with the 3PT. I would mount the top link cylinder very similar to the way the HDP kit is except using a rigid link instead of the floating or "lost motion" link to the cylinder rod end. The position control lever would need to be left in the lowest position so that the 3PT is not trying to fight the cylinder. The lower lift arms would rise and fall just the same but under power of the cylinder.
I would hate to buy another cylinder for several hundred dollars if the existing Fit Rite Hydraulics cylinder can be used especially when it adds HDP. Serious engineering? That's what retired engineers do with their spare time.:confused2:
Your feedback is appreciated Brian, as always.

 

[Zebrafive]

I'll be watching to see what you come up with!

 

[MtnViewRanch]

Brian, that would be way too easy. You challenged me and that's all I need to proceed.
It seems a shame after buying the top cylinder from you, which works great by the way, to not be able to use it with the PHD. I did a little work with the PHD today and observed the angle change between the inverted-U piece that attaches to the lower lift arms and the main beam when the PHD is raised and lowered with the 3PT. I would mount the top link cylinder very similar to the way the HDP kit is except using a rigid link instead of the floating or "lost motion" link to the cylinder rod end. The position control lever would need to be left in the lowest position so that the 3PT is not trying to fight the cylinder. The lower lift arms would rise and fall just the same but under power of the cylinder.
I would hate to buy another cylinder for several hundred dollars if the existing Fit Rite Hydraulics cylinder can be used especially when it adds HDP. Serious engineering? That's what retired engineers do with their spare time.:confused2:
Your feedback is appreciated Brian, as always.

OK, maybe I shouldn't of said serious engineering. :laughing:

I just hate to see people take all the time and money and end up with something that isn't really any less money and isn't any better, maybe even lesser of a product. You realize that with the OEM down pressure units, you can have constant down pressure. There is a by-pass valve to allow for this. So don't forget that valve, it is nice to have that constant down pressure when you are in really hard ground. I see on TBN many times where people want to build it themselves and that is fine, especially if the person knows what they are doing. But all to many times I see time and money spent where the person would have been money and time ahead to have just bought the manufactured product.

Good luck.

 

[EddieWalker]

I tend to come up with the most complicated ways to fix a problem, then over time, work my way towards a simple solution. My soil is all hard packed clay and it can be rather difficult to drill into with my 3pt post hole digger. I tried adding an extension to the boom and adding weights to it to increase the amount of down pressure without any great success. Then another member on here posted about different cutting teeth and attachments for his post hole digger and I realized that my problem was that I was using a dull drill. I bought a different auger with replaceable cutting teeth that are night and day over what I started out with.

What are you using and what are the cutting teeth like? Having more pressure wont cut or dig any better if you are drilling with a dull or non existing cutting edge.

Eddie

 

[npalen]

Zebrafive--You threw another log on the fire, didn't you.
Brian--Good point on the relief valve. Would need to back off the relief valve on the DCV.
Eddie---The irony is that I'm not having any trouble with the PHD as is, I'm just trying to fix something that, in my case, isn't broke. I like thinking "outside the box" in the hope of coming up with something new and useful. It's easier to do when retired.

 

[npalen]

I tend to come up with the most complicated ways to fix a problem, then over time, work my way towards a simple solution. My soil is all hard packed clay and it can be rather difficult to drill into with my 3pt post hole digger. I tried adding an extension to the boom and adding weights to it to increase the amount of down pressure without any great success. Then another member on here posted about different cutting teeth and attachments for his post hole digger and I realized that my problem was that I was using a dull drill. I bought a different auger with replaceable cutting teeth that are night and day over what I started out with.

What are you using and what are the cutting teeth like? Having more pressure wont cut or dig any better if you are drilling with a dull or non existing cutting edge.

I totally agree on the need for sharp cutting teeth on the earth auger. Many of the same principles involved in drilling steel with a sharp bit of appropriate geometry.


Eddie

I totally agree on the need for sharp cutting teeth on the earth auger. Many of the same principles involved in drilling steel with a sharp bit of appropriate geometry.

 

[buickanddeere]

As previously stated it will cost less and work better to purchase a hydraulic driver PHD with a proper auger that mounts on the loader bucket.
Down pressure , reverses if caught and no shear pins.

 

[npalen]

Do you normally use the loader mounted PHD in float mode or hydraulic down pressure? Just curious as it seems like the loader itself would provide plenty of down pressure. Does the side loading of the PHD present any issues with twisting the loader? I assume you mount it to the side for visibility?