Non electric , non combustion engine powered mechanical ceiling fans.

Non electric , non combustion engine powered mechanical ceiling fans.

Thread: Non electric. non combustion engine powered mechanical ceiling fans.

Join Date Jan 2006 Location Brookfield, Wisconsin Posts 3,089

Non electric. non combustion engine powered mechanical ceiling fans.

I came across the below post about mechanical ceiling in New Orleans that are not powered by electricity. steam or some other combustion source. According to the poster a person yanks on a chain every half hour or so to keep the fans running.

Some old buildings and stores used a water motor to drive ceiling fans. This was a small impulse turbine, and drove multiple ceiling fans via round leather sewing machine belting. In cities where there was a steady supply of water from the mains, the water motor drive was used. If you have a spring at your cabin that runs continually and has a high enough head, you could use a water motor. These were commonplace for driving light loads in cities or country home with high-head spring water that ran continually. Look up Backus Water Motor.

Now we get to the first law of engineering, as I explain it to non-technical people: There is no free lunch. Meaning: if you think you can get something for nothing, it ain’t gonna happen. Free lunches in the tavern meant you bought their beer. If you have a human powered fan, you are going to have to wind up a weight every so often. If you need a ceiling fan, chances are it is hot or muggy. Winding up a weight in a relatively short time is going to get you even hotter, so your kicking back to enjoy the breeze off the fan is just temporary as you will be playing it again with winding up the weight. And, the energy you put into winding up the weight will not all be converted to turning the fan. A lot will be lost as friction through the gearing driving the fan.

The human powered device that works by yanking on a chain is probably nothing more than a weight with some sort of escapement to slow its descent. Review your basic physics (if you took physics in HS) and you get into potential energy. Raise a heavy weight a short distance in a short time, and you are storing potential energy. Let that weight descend VERY slowly and control its descent rate with gearing, and you are using a portion of the potential energy you stored when you raised the weight. If a 50 lb weight were raised 7 ft (ceiling height ?) you have stored 350 ft-lbs. How fast you raised the weight, measured in seconds, and you have the basis for converting your sweat into horsepower. Now, if you were wrap the chain or rope you raised the weight with around a drum (such as a winch drum), and let the weight drop, the shaft on the drum would spin wildly and the weight would hit the floor in the blink of an eye. If you applied a set of speed increasing gearing to the winch shaft, and then drove a series of fan blades, you’d have a means of slowing the descent of the weight and getting some of your stored energy reapplied by turning the fan blades. The fan blades would also act as a kind of air brake to slow the descent of the weight. You would need a fairly high gear ratio in the gear train to put enough drag on the winch shaft to slow the descent of the weight to something like 6 or 7 ft in an hour, and fairly steep pitches on the fan blades to add some braking effect. You would also need some sort of over-running clutch (sprag clutch or ratchets) to allow you to wind up the weight without dragging all the gearing and the fans along for the ride. If you had to do that, you’d really raise a sweat.

BTW: If you look at music box movements and old clock movements from medieval times, both use a form of air brake to govern their operating speed. Modern spring wound music box movements have used a simple paddle type fan to govern the speed at which the movement operates (and to keep the music in proper tempo). Medieval falling-weight clocks sometimes used a similar turning paddle type of fan to act as a governor on the escapement. These were the extreme, the fans were not pitched to move any air, but to churn it for the sole purpose of providing resistance to hold a mechanism at a certain speed. What you are doing is reinventing something like a lighthouse drive, or tower clock mechanism, which worked with a falling weight. In tower clock and lighthouse drives, a falling weight was raised to a high height and allowed to descend on a chain or cable. The center of a stairwell (or spiral stair in a light house) was used as the well into which the weight descended. A lighthouse drive or tower clock usually had to be cranked up once per day. Light house drives ran at least 8-10 hours on one winding up of the falling weight. However, the lighthouse keeper had to ascend all the spiral stairs to get to the top of the light house to wind up the weight, then make his way back down again. While the lighthouse drive then ran 8-10 hours, if one calculated the HP the drive produced vs the energy the keeper expended going up the lighthouse stair, winding the weight up, and going back down again, the inefficiency is high. If you have ever visited a lighthouse and walked up the stairs to the top, you can appreciate what the keepers had to do daily.

My own opinion: get a deep cycle battery, inverter and some solar panels. Use a conventional electric ceiling fan. You take the hit at the cash register, but you have electricity available for other light loads and you are not experimenting with gear trains and weights.


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