Saturday, June 16, 2007
Today, we tested our four inch cylinders and pistons. We were concerned that the forces required to lift water 28 feet would be too great with four inch pistons for a smaller (100 lb.) person to manage. It turns out that it is workable as long as the pump provides enough mechanical advantage. What happens is that the smaller person just has to move down the treadle towards the mast and away from the pumps. When they do so, and take the same size steps at the new location, the pistons travel a shorter distance in the cylinders, and the pump just moves less water. It means that a smaller person can still lift the water as high, just not as much water as fast. It makes sense if you think about it. We also learned a number of other interesting things as well. For example, it's much more comfortable to operate the pump if you're facing away from the pistons than if you're facing towards them. As the treadle travels downwards, if you're facing away, your toes point downhill. Turned the other way, you find yourself standing on your toes, with your calf muscles under strain, which causes fatigue very quickly. It's also very helpful to have an adjustable stop for downward treadle travel to accomodate different sized people. If there is a solid stop at the bottom of the treadle's travel, it's much easier to keep your balance and actually have a little rest at the bottom of each step. That's the reason for the steel rod you see sticking out of the right hand side of the treadle frame in the photo. It was our quick and easy adjustable treadle stop.
I should also say somewhere that this pump moves a lot more water without much more effort.
So, what has to happen next is that we have to disassemble our frame, and cut away everything that doesn't have to be there, and make some of the parts more durable and rigid.
The frame will probably shrink in height by about seven inches, which is good from the users standpoint. The cylinders and connecting rods will also be shortened by about three inches. Oh, yes, we have another video which will follow as soon as we can upload and link. Stay tuned.