Sequence valves

[Aquamoose]

I'm hoping to get some advice from you hydraulic gurus about sequence valves. I built a tree puller to pull out thin pine/fir saplings on my property as I have too many and it's very dense in places so to mitigate the fire danger, I'm thinning them by pulling them out. I have absolutely no problem plucking them out of the ground but they would often snap while moving them as the tops would get caught among other trees while trying to move them to a staging area for later chipping. I already have a stout 3 foot high guard to prevent saplings from falling towards me and I'd like to put another set of horizontal grapple fingers to hold the sapling upright on it while transporting. The top of the guard to the jaw is approx 4 ft so there's plenty of leverage to hold.

To do this, I believe a sequence valve would be the ticket where one 3rd function would control both the jaws and the top grapple. Adding a shut-off valve to prevent the top grapple from closing is the plan whenever I'm working with a bigger tree. My jaws can crush the trunks so I'm always careful in applying the right amount of force and I do it well. Is it possible to have a setup so the grapple on top actuates first, then the bottom jaws second then when I'm ready to release, both open equally?

How would I go about building this setup?

 

[Aquamoose]

This youtube link is what I have in mind. I wish they would slow it down and illustrate it on paper/whiteboard so I can see the connections. I did note that both cylinders retracted at the same time, which I'd like but would like to understand how that happens. Is that an option that all sequential valves have or?

Eaton - MiHow2 - Steps Necessary to Effectively Set Up a Hydraulic Sequencing Circuit - YouTube

 

[muddstopper]

Sequence Valves - YouTube

 

[oldnslo]

Aquamoose,
I would suggest that you put together a detailed step by step sequence of events on how you want this machine to operate. Both opening and closing and any other possible combinations of movements. Then start working on the circuit components. Sequencing systems can get complicated quickly.

 

[Michael In Tennessee]

I have just a tad of knowledge in this area, but would a orifice/check valve work on the cylinder you want to slow down? On the primary stroke, the orifice slows it down allowing your second cylinder to stroke first. On the return, the check would bypass the orifice allowing normal operation. I have done this on pneumatic circuits with good success.

 

[Aquamoose]

Aquamoose,
I would suggest that you put together a detailed step by step sequence of events on how you want this machine to operate. Both opening and closing and any other possible combinations of movements. Then start working on the circuit components. Sequencing systems can get complicated quickly.

Thought I mentioned it in my first post. First top grapple, then bottom jaws so I can adjust gripping pressure. When I’m ready to drop the tree, both to open at the same time.

 

[aczlan]

Thought I mentioned it in my first post. First top grapple, then bottom jaws so I can adjust gripping pressure. When I’m ready to drop the tree, both to open at the same time.

It sounds like you need an adjustable pressure relief valve on the close side of the upper cylinder. Then have the tank port of the pressure relief valve go to feed the close side of lower cylinder. Put a check valve on the close side of both cylinders and tee that back into the close line before the pressure relief valve that so that it will let fluid back out of the valve once you release pressure.

Aaron Z

 

[oldnslo]

Thought I mentioned it in my first post. First top grapple, then bottom jaws so I can adjust gripping pressure. When I’m ready to drop the tree, both to open at the same time.

Do you need to control or regulate the top clamp grip pressure Vs the bottom clamp or just close the top clamp first and then both clamp at the same pressure?

If just close top first Mike in Tennessee has very simple solution that could would.

 

[aczlan]

Do you need to control or regulate the top clamp grip pressure Vs the bottom clamp or just close the top clamp first and then both clamp at the same pressure?

If just close top first Mike in Tennessee has very simple solution that could would.

Sounds like the top can close as tight as it wants, but the bottom needs to be controllable.

Aaron Z

 

[Aquamoose]

The ideal sequence...

- Pull up to a tree
- Top grapple the upper portion of the tree fully
- Bottom jaws close
- pull / transport tree
- position tree to desired location & tip forward
- both grapple & jaws open simultaneously

I don’t know if I should be looking for relief valves or sequencing valves. I read it that a relief valve CAN be a sequencing valve but identifying/locating one is a challenge for me. Bailey’s has none and Surplus center isn’t much help with options. The long video helps but wish the creator of the video would use a part number of a sequencing valve as a reference.