I also would much prefer electric methods but they want mechanical. That is my plan B if hydraulic doesn't work out though.Bill Shields wrote: ↑Sat Jun 04, 2022 6:36 pm I would drive a dc generator rather than a gear motor pump.
That's been my plan too. It will let me test out different props and already has the right angle mechanics in place. I"ll just need to adapt it to mate with the vertical shaft and pump.
That is fairly complicated so bare with me.BigDumbDinosaur wrote: ↑Sat Jun 04, 2022 9:10 pm Now that we know something about the application, I have to ask why mechanical power transmission can’t be used.
This whole thing is getting installed on a really big floating platform in a river. There will be a round opening in the platform (they're calling it a moon pool) that the prop and shafting will have to fit down through. The table looking part in my "sketch" will be bolted to the floating platform. On top of the raised platform will be a big metal sculpture of a bird. If that was all it was this would be easy. Here's the complicated parts:
-the river is called a "tidal river"? The direction of the flow of the water actually reverses during the day which I have never heard of. They sent me a graph of the river flow over a few days and its plotted just like a sine wave. Positive values are one direction, negative values are the other.
-the bird sculpture's wings need to move. I'm not building the bird so I'll need to figure out the mechanics of making them move later.
-the whole assembly, not including the raised platform, needs to rotate with the direction of the water essentially making the sculpture point in the direction of flow like a weather vane does in the wind.
Problems I need to overcome:
-most importantly, start telling the guy who takes on these nightmare projects no.
-the prop, vertical shaft and some sort of rudder cannot be bigger than the opening in the platform. There is no dry dock available for install and I was told divers are also not an option. So everything needs to be able to be lowered into the water through the opening. The opening is supposed to be round which also means I may have to make the lower portion off center so it can fit down through. That's one of the biggest reasons a mechanical transmission isn't feasible. Getting this to work at all will be challenging enough. Transferring the rotary motion of the prop through a bunch of right angles up to the top of the turntable is basically a fantasy.
-I need to build in some sort of speed limiter. I will have to engineer this based around normal water flow rates. I'm concerned that during heavy rain the water will move much more quickly and I'll need to make sure this won't rip itself apart. Thinking about trying to mechanically limit the speed makes my head hurt. With fluid power however, I should be able to handle it with valves. In theory at least.
-it needs to be serviceable. Everything breaks at some point. Prop breaks, bearing goes bad, whatever, the lower unit will need to be able to be pulled out of the water without calling in a crane to remove the entire structure in one piece. Another reason a mechanical transmission would be tough.
The only way I can think to pull this off is using fluid power to get the rotary motion from one place to another, so I need to start testing hydraulics which is why I'm asking about gear pumps. I've replaced hydraulic parts on equipment before and I understand the concepts of hydraulic systems, but this is my first time starting from scratch. I've also never tried to build something powered by a river and a prop. The theory and principals check out but, I won't know until I try.
So, can anybody recommend a small, commonly used/available cast iron gear pump?
Griz