Constant Stroke Hydralic cylinder

[Ravenhawk57]

Am wanting to build a servo controlled cylinder that recycles itself. I want the cylinder to cycle both ways with a manual override. I need some help with this. Am building an auto fed wood splitter. Or rather trying to. Any help would be appreciated. Or where to look for help. Thanks

 

[aczlan]

Do a search for an auto split valve. There were a couple threads on that a few years back and that valve does pretty much what you want to do.

Aaron Z

 

[muddstopper]

I have considered building a similar splitter. I came to the conclusion that such a auto cycle feature would be pretty dangerous to use. Since my knee replacement, I stumble like a bull in a china shop. I figured one slip and I could lose a hand, arm, or worse.

as for the automatic cycle, the autocycle valve is one option. Simply pull two levers and the valve fully extends and retracts one complete cycle. Cycle can be stopped by simply centering the lever on the valve.

For continuous cycle, several ways to accomplish. Electric solenoid valves and limit switches might be the easiest. You would need a valve and subplate large enough to carry the flow. Rig up a slide rod on your push plate that could activate the limit switch at each end of the stroke and install a stop button to break the electric circuit when you need to stop the cycle. Personally, unless I was using some sort of equipment to load the wood to be split, where I didnt need to place body parts in close proximity to the push plate and splitter wedge, I would forget about even considering making a wood splitter with a continuous cycle.

 

[Ravenhawk57]

( I too have a new knee ) also am 75 Mudstopper but this will be self fed splitter and not for fire wood. Am looking at using 20" dac around 4 to 4 1/2 bore with a 1 1/2 rod using a 16 gpm with a 14 hp motor. Stroke cycle approx. 4 5 seconds. Am looking at the solenoid set up just don't have the experience and looking for some advice on that end of things. Actually I don't need that much tonnage just the speed. Probably less than 10 tons will work. But when you get to speed things need to be beefed up just a smidge. Any comments you are willing to provide will be appreciated. Thanks

 

[muddstopper]

there are several things to consider using solenoid valves, you will be required to add a separate relief valve before the solenoid valve to adjust the pressure setting. you will also need a valve large enough to handle your oil flow. A quick look at surplus centers website shows this 21gpm valve 12 VDC 21 GPM ARGO RPE3-6 DA HYDRAULIC DO3 SOLENOID VALVE | Solenoid Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com that should work. You will also have to purchase this subplate, 1 STATION DO3 SUBPLATE OPEN CENTER | Subplates | Hydraulic Adapters & Fittings | Hydraulics | www.surpluscenter.com to go with the valve, or they also have multisection subplates if you want to control more functions.

Next you will need some sort of switch to swap which solenoid you want to control. I like going heavy duty with something like these, Heavy-Duty Limit Switches. You can get by with smaller,, cheaper type switches, but you get what you pay for. You will also need to wire in a electric power supply stop button so you can cut the elec, to the solenoid valve and prevent cycle.

To make the limit switch work with the valve, you will need to fabricate some sort of plunger or sliding rod that will trip the switch at each end of the stroke. The switch would need to be wired so that when centered, it operates one end of the solenoid valve and when activated, it sends power to the opposite side of the valve. my suggestion for the switch activating rod would be to attach a rod to the side of the beam so that it will float in each direction. On each end of the rod attach a piece of angle iron that the pusher plate can contact at each end of its stroke. When the cyl is fully retracted it will activate the limit switch in one direction and stay in that position until the pusher plate reaches full extension when it would pull the rod away from the limit switch, thus reversing the electric current and energizing the opposite solenoid. I dont know if I explained that where you can understand it, but this would be the easiest method I can think of to have a continuous cycle.

The solenoid valve and subplate are rated for 3050psi, you would want to adjust your relief valve at or below, ( I would stay at lease 100psi below the 3050psi rateing) that number and your tonnage will be a product of the relief setting and your cyl size

 

[Ravenhawk57]

I'm gonna work on this and I appreciate the info. Will make a layout and let you look at it later. Thanks Joe

 

[4570Man]

They make valves with a detent on both ways. You could bump it back and forth with linkage.

 

[muddstopper]

I'm gonna work on this and I appreciate the info. Will make a layout and let you look at it later. Thanks Joe

When buying a limit switch, just remember that they come in 2 pole (2wire) and 3 pole, (3wire). The 2 pole can be either Normally open or normally closed, only and will not work for your autocycle, unless you use two switches. The 3 pole will have a common leg for power in and a NO and a NC leg. This is the type switch you need. You do need a stop switch to interrupt the power supply going to the limit switch in order to stop the cycle. If you make your slide rod adjustable so that you can adjust the bump stops, you will be able to adjust the stroke length for different lengths of wood. Splitting 16in wood, adjust stroke for 16in, need to split 24in wood, just move the bumpstop so the cyl will travel 24in.

At work, when limit switches where used in a lot of different applications, we mounted the switches on a 1in sqbar and just slid the switch to adjust cyl travel. We used pressure switches, Can's (Controller Area Network) and string pod systems to set cyl range. All that computer stuff took the place of the limits switches and proved a pain to maintain. Now instead of taking a test light and checking the limit switch for power and fixing the problem in 5min, it takes a hour of trouble shooting just to find you had a broke network wire. I liked the Kiss systems a lot better and they are a lot easier to work on.

 

[Ravenhawk57]

Was a welder and pipe superintendent in the oil fields for a good many years. Understand the problem. Our engineers of today have no clue, its computer this and that, and along with that is no experience. Most of the stuff I worked on is still the same today. Some things don't need to be improved. Wood splitters are a prime example. There are none that are planned to be used. Everything is located with a look to cost of fittings. Not for the convience of the operator. I have BBQ house in Townsend Tn. which is about 18 miles from Gatlinburg or Pigeon Forge and had to purchase a new splitter, all have the valve installed so it hits you in the head or face if you have it in a vertical position. I appreciate all the information you have passed on. Sorry about rant. My help gets to me sometimes. Thanks Joe

 

[muddstopper]

I have plans in my head for a fully automatic splitter, bot to many unfinished projects and no real need, to ever get around to building it.