Getting high speed from a slow moving object.

  • Thread starter Thread starter craigo
  • Start date Start date
  • Tags Tags
    High speed Speed
AI Thread Summary
The discussion centers on the challenge of generating high-speed rotation (1,000 - 2,000 rpm) from a slowly descending 250 lb weight, limited to a drop of 1 foot per hour. The initial idea involves using gears, such as a rack and pinion, to convert the weight's slow descent into faster generator rotation. However, concerns arise regarding the practicality of gear sizes and the torque generated by the weight. The conversation highlights the limitations imposed by the law of conservation of energy, indicating that the maximum energy produced from the weight's descent is only 0.1 watts. Ultimately, the consensus suggests that achieving the desired electricity generation with the specified constraints may not be feasible.
craigo
Messages
1
Reaction score
0
I am trying to figure a way to turn an automobile type generator shaft at realtively high speed (1,000 - 2,000 rpm) using a weight, say 250 lbs., on a pole. The catch is the weight can only drop at about 1 foot per hour. I thought it could be done using gears, such as rack and pinion. A gear on the generator (attached to the weight) would ride down a track on the pole, thus turning the generator as the weight dropped. Obviously, that wouldn't be fast enough. Modifying the gearing may be theoretically possible, but in reality the small gear would be too small to work with such a weight. And the large gear would have to be very large. I'm trying to keep this on the small side.
I believe it can be done using the weight. Somehow the constant pressure of the weight should be able to generate enough torque(?) to raise the speed. Not unlike they way we would stand on our bike pedals to help climb a hill. Perhaps not unlike the child's top that has a push-down screw mechanism that causes it to spin faster as more effort/weight is pushed upon it.
I'm not locked into pulleys, gears, belts or whatever. Those are just my current lines of thought. My only limitations are: that the weight must fall about 1 foot per hour; I want to create a reasonable amount of electricity; and I want to keep the whole thing (except the weight and the pole) within about 8-10 cubic feet.

There must be a simple solution that I'm missing. But my brain is starting to hurt, and I need some help. Thanks
 
Engineering news on Phys.org
Please note: the law of conservation of energy applies. Lowering a 250 lb weight 1 foot per hour can generate a maximum of 0.1 watts (PE=mgh). That's why you are having so much trouble making this device. It can't work.
 
Hi all, I have a question. So from the derivation of the Isentropic process relationship PV^gamma = constant, there is a step dW = PdV, which can only be said for quasi-equilibrium (or reversible) processes. As such I believe PV^gamma = constant (and the family of equations) should not be applicable to just adiabatic processes? Ie, it should be applicable only for adiabatic + reversible = isentropic processes? However, I've seen couple of online notes/books, and...
I have an engine that uses a dry sump oiling system. The oil collection pan has three AN fittings to use for scavenging. Two of the fittings are approximately on the same level, the third is about 1/2 to 3/4 inch higher than the other two. The system ran for years with no problem using a three stage pump (one pressure and two scavenge stages). The two scavenge stages were connected at times to any two of the three AN fittings on the tank. Recently I tried an upgrade to a four stage pump...
Back
Top