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You may want to print this picture to refer to later as an assembly guide.
All the available plans for ram pump valves are based on converting a conventional foot valve to operate in reverse. The trouble with this solution is you end up with a valve that is flimsy, wobbly and unreliable. It works, but it wears out too fast and jams up too much. My design takes care of it by starting from scratch and making it strong. My wife says I am strong like bull and smart like tree so I make everything I build that way. I also like to use whatever I have around the farm so that is exactly what I did. You could build it prettier and simpler, but recycling scrap is a priority around these parts, especially if you are broker than the ten commandments... This project really paid off for us, it just works great.
You need the picture of all the valve parts to see that it's easier to build than than it sounds below...so let's GO...
I had a 2" to 1.5" copper reducer with a short piece of 1.5" pipe attached and that makes the valve body. I also had a 6" brass tail stock sink connector that I inverted and soldered inside the reducer because that had a nice smooth lip that makes a perfect valve seal with no work at all. If you have a new reducer and smooth it off with sand paper, you likely don't need the tail stock step but you do need a smooth edge for the valve seal to contact or else you will not get it working. Now drill minimum 2 (or 4 is better) 3/4" holes through the pipe just above the reducer and smooth the edges and presto, your exhaust port is all done.
Next problem... how to replace the O ring seal used in converted foot valves. It routinely wears out or slips out of place and stops your pump. So, let's not fool around. Take a hockey puck and use a hole saw to make it 1.85 " in diameter so it fits inside the 2" reducer and has lots of clearance around the outside. Drill a 1/2" inch hole exactly in the center and put a bolt and nut on it so you can hold it in your drill press. Then spin it with a file against the edge so you get a nice smooth beveled edge about 1/4" long. This presses up against the smooth tail stock lip to form your valve seal so make it as smooth and even as possible and it will work better.
Now get some plastic washers that slide easily inside the tail stock piece. I had a piece of scrap plastic around so I turned it on my lathe to fit. It works as a centering guide for your valve to keep it closing and opening in a straight line. (This is one reason other converted valves often fail.) The fit needs to be loose but not too sloppy, say 1/16" clearance.
Now make a top cap. I turned a scrap piece of aluminum so that it fit into the tail stock and had about 1/2" of overhang left at the top just like a cupboard knob. The half inch center hole is threaded to fit the rod, but you could just use a clearance hole and a couple of retaining nuts on the top and bottom. You need to be able to adjust the position of this cap up or down on the threaded rod as this is the regulator that controls the pump cycle frequency and efficiency. A giant wing nut would work too, just something to hold the valve stem assembly from falling out the bottom due to gravity when it cycles up and down.
Now assemble your valve. Put about 6 0z. of weight on the bottom of the threaded rod. (I drilled a 1/2" hole in a piece of scrap steel, (you could use heavy washers), just smaller diameter than the hockey puck which sits nicely flat against it. Put the puck on the rod then a washer on top about 1/2" smaller than the puck bevel then lock it in place hard with a retaining nut. (This valve cycles 2.5 times per second and receives lots of force (remember that water hammer discussion earlier, well, the hammer part is for real!) so lock it down strongly. This is another reason foot valve conversions fail as there is no way to stop the valve assembly from wobbling all over the valve body and it wears the stem or guide too quickly and frequently pops the foot valve O ring off the groove. That can't happen with my brute of a valve.)
Now put another retaining nut on the rod about 2" above the puck assembly. The valve cycles up and down about 1/2" so you want your plastic center guide to sit above the exhaust ports when it's all assembled and resting in the down position. Now put a retaining nut on top of the plastic center guide and tighten it down.
Almost there. Slide the finished valve stem assembly into the reducer so the threaded rod sticks out the top. Now spin on your top cap adjuster until it slides into the top of the tail stock and permits the valve assembly to move up and down about 1/2". Put a wing nut on top of the cap to hold it in place. You will have to loosen or tighten this cap a few turns at a time to make your pump operate optimally.
The hard part is over.
Now take the fire extinguisher and make a pressure tank out of it. You do that by screwing off the extinguisher handle and stuffing a recycled, deflated 20" bicycle tube inside the tank and then inflate it to about 5psi., that's it.
Next, assemble the pump like you see it in the parts list picture and lash it down to something strong or it will walk all over the woods. (remember that water hammer discussion earlier, well, the hammer part is for real!) so lock it down strongly, I used 4 x 3' fence bars bolted to a board and a 10" concrete block. I strapped the pump to that with copper plumbing straps and stainless screws. The feed water pipe is connected to the pump with a rubber plumbing connector.
Here's how to operate it:
To run it, you need about 5' of feed water pipe for every 1' of fall below your pond or creek water surface. I have 10' of fall and 50' of feed pipe supplying 3 gallons/min. (A little longer would be better say 5.5:1)
Now manually push (cycle) the valve stem up and down about 30 or 40 times to fill the pressure tank. These pumps need back pressure in the tank to operate automatically. When the pump starts to cycle on it's own, you will want to screw the adjuster cap up or down to make the cycle frequency about 60 - 150 cycles per minute.
Experiment with the cycle frequency to find what delivers the most water for you. Lots of troubleshooting guides on the net to help you fine tune it. You may need to add or remove some weight off the bottom of the valve stem if it cycles too fast or slow and you don't have enough adjustment available by turning the upper valve cap. A little denial and error and you will find the sweet spot to get it running smoothly.
I have found that if it cycles too fast, it won't build up any pressure and the delivery flow is low or stops. If it cycles too slow, delivery flow is weaker and you use more feed water than necessary and you can drain the feed pipe if your supply water is limited. Mine seems to deliver the most water at a cycle rate of 150/minute.
Enjoy your gravity powered water pump, it's the closest thing you may ever see to perpetual motion... Hopefully you can see the movie of it working.
This is the best hobby project I have ever built from scrap parts and recycled junk. We use it every day all summer long and it facinates everyone who comes to visit us while saving real money!