# How can a mechanical clock be powered by wind in a reliable, constant way?

## Picking up the context

This is a follow-up question to the technologically accurate watermill clock, available here. In this case, we're not using water to make clocks, but wind! Wind will be the power source to... power the clock mechanically. So let's lift off into the world of physics and engineering together!

## The question

The watermill clock had issues having a simple, yet physically correct mechanism to display the time, given a constant input current. In this case however, I believe the main issue is having the power input being constant and reliable in the first place. Indeed, it's not like water where you could always put it in a storage and use valves, the container's shape or Mariotte's bottles. Wind is chaotic by nature, having strong and weak times, but it's also not a thing you can contain in a tank like most other materials.

#### Therefore, how can wind input be made constant in order to accurately power a mechanical clock?

In order to answer, I guess we have to think about how to keep a strong wind lower to not overpower the mechanisms, and how to keep in some power to keep the clock working during lowtimes. There are also turbulencies, and well, wind orientation to take into account. There can be other technical issues I haven't pictured, so tell and find a solution about them if I've missed one.

## Additional data

Here are some intel that should help you understand the intentions :

• The clock that will use this system is your typical town's council or railway station clock. It's near the coastline (beach height), typically in an oceanic climate. It's relatively big, and therefore requires a little more power than your wrist-watch or kitchen clock.
• Since we're talking about time-keeping, accuracy is paramount, both in stability (no variation over time) and precision. The more accurate and constant you can make, the better. I'm expecting a precision in the order of minutes or half-minutes at the very least, though more accurate is better.
• Technology up to today is available, but no oil, gas (outside wind, obviously) or electricity component however! The key point is transforming wind forces into mechanical power, so you can't use a regular wind turbine and batteries to power electrically the clock; That'd be just too simple 🐶.
• The shape and size of the wind engine can be whichever you like better : Windmill, wind turbine, cylinders, weather vane... Just don't make it 1km long and gold plated :p.
• The longer you can keep the clock alive with low or no wind, the better, but reach first the minimal accuracy criteria.
• Focus your efforts on making the wind give a constant mechanical force. You can talk about its relationship with the clock mechanisms, especially if it's important to accuracy or power conversion : Springs, pendulums, I don't know! But just remember the clock itself is not the main point.
• If the wind engine is not too expensive to repair or replace, it can take a hit from heavy storms (let's say > ~90km/h or ~50kn). The clock's core should not fear damage by receiving too much pressure in, though.

Ideally, your answer should go beyond theory and put things into practice. Talking about the base idea is a nice starting point, but it's to be put in a place with the environmental context above, therefore some dimensional specs would sure be helpful to me ^^.

If one of the above condition prevents you from reaching the goal (making a wind-powered clock), you can alter it slightly in order to reach it. For instance, if wind speed is just too low even on seaside, you can tell you had to increase it a little for the purpose of answering the question. After all, a partially successful answer is better than none 🦋.

• I'm not sure if it's in the spirit of the question, but if a water-clock is a solved problem, why not simply use a (smaller) water-clock and lift water using wind-power...? Have a big enough reservoir to provide a buffer for wind variability, and you should be all set.
– Qami
Apr 15 at 2:39

## 4 Answers

Wind turns windmill, windmill lifts weight, weight powers tower clock. Use two weights to have power when the windmill is lifting one of them. This obviously decouples the strength of the wind from the clock mechanism; there is no need whatsoever to make the wind give a constant mechanical force.

When you wind up a wristwatch you don't need to make sure that you supply a constant force. You just need to supply a reasonable force to wind up the spring. Once you have wound up the spring, the spring will power the wristwatch and the balance wheel and escapement will regulate the power drawn by the watch.

Big Ben is wound three times a week, and the winding takes over an hour.

Big mechanical clocks can be made surprisingly accurate. For example, the Big Ben in London is accurate to about two seconds per week; obviously, somebody must take care of it and adjust the mechanism as needed.

Big Ben is accurate to within two seconds per week. The pendulum is adjusted by adding pennies made before the decimalization of the United Kingdom’s currency in 1971 to the weight. Each penny causes Big Ben to gain 0.4 second per day. (Betts, Jonathan D., "Big Ben". Encyclopedia Britannica. Accessed 15 April 2022.)

• @Tortliena: I don't understand what you don't understand. Once you have a powered rotating shaft you can use the power to turn the spool on which the chain holding the weight is wound. Works exactly like the key you put into the winding hole of the clock and turn and turn to lift the weight. (Please don't tell me you have never seen a grandfather pendulum clock.) (You do know that tower clocks are powered by weights which serve to power the shaft on which their chains are wound, right? Like an oversized grandfather clock.) Apr 14 at 23:47
• @Tortliena: You apparently don't know how pendulum clocks work. Most of the time, the weight pulls down on the chain, which powers the main shaft, which powers the clock. The weight moves down little by little. Eventually, the weight reaches the lowest point; at that point, you need to rewind the chain, lifting the weight up, so that it can then power the clock again. Normally you use a key to turn the spool to lift the weight. Instead of a person doing the work, you can use wind power to lift the weight back to its upper point. (In wristwatches, we use a spring to power the main shaft.) Apr 14 at 23:56
• @Tortliena: The point is, all mechanical clocks in the end need a power source. The power source can be a coiled spring, which uncoils little by little and eventually needs to be rewound; or a weight, which is suspended from a chain, which is spooled around a shaft: the weight goes down little by little, powering the main shaft. The pendulum (in grandfather clocks) or the balance wheel (in small clocks and wristwatches) moves the escapement which is the mechanism that ensures that the clock draws only as much power as needed from the primary source. Apr 15 at 0:03
• @Goodies: The question does not ask for a wind clock, it asks for a mechanical clock powered by wind. Apr 15 at 1:27
• Probably would need an operator to switch from one weight to the other when the current weight is all the way down, unless you can automate that somehow. Also might be good to have a manual crank in case you get several wind-less days in a row... Apr 15 at 14:02

AlexP mentions it in his answer, but doesn't go into detail with it, but your answer is springs, specifically wound springs like in a wristwatch.

These can be fairly small while still having decent power to run a clock. Also, because of their small size, you can have multiple springs to take over when one winds down. This way you could potentially run a clock for a week or more during a calm period.

And these springs can be wound individually, so when one spring is fully wound, the next spring in the line can get wound, or however you want to run the clock. I'm imaging the springs being engaged one at a time by either the clock or the winding device, rather than all springs acting at the same time. In my thinking this is "series" rather than "parallel", yet it's sort of a hybrid.

I suggest running the springs in this hybrid series/parallel, since running them in parallel can cause problems when one breaks. In parallel, they are all engaged full time and if enough break before you realize what's happening, you likely have a cascade failure of all springs. Running the springs in series also has issues, since all the springs would still be engaged all at the same time, so removing one or one failing causes everything to just stop.

Granted, running them in this hybrid series/parallel system also has drawbacks in increased complexity, but you'll be able to replace weak or broken springs more easily without losing time or having downtime.

You'll likely want to have an automatic system built in to switch between springs when they wind down, as well as when they are being wound. You also likely don't want to be running your clock on the same spring that's being wound.

As someone mentioned in comments, you'll also likely want to have a manual winding mechanism, in case the wind goes calm for a while. You can even make it animal powered, like cattle/oxen/horses, or maybe ridiculous like dozens of hamster wheels. Or double-down and hook it up to the stationary bikes of the gym next door.

But really, use a vertical wind turbine so that you can pick up the slightest amount of wind in any direction at any time. These are very efficient turbines and require less maintenance than a standard turbine. These can also be made to be visibly aesthetic, as opposed to most fan blade based wind turbines.

Edit: More thoughts
I got to thinking about the spring system and how to do maintenance on it while the clock is working. Each spring could be a self-contained cartridge, like a server in a server rack. Pull one out to do maintenance on it and immediately replace it with a "spare" spring that's already completed maintenance as well as already wound, so it's ready for use as soon as it's slid into place.

This would allow for delicate or time consuming repairs to be done away from the clock and without any kind of interruption of the clock. At least for the springs anyway. Having multiples of these spares would allow more than one person to work on different springs at the same time without them being in the way of each other, and without relying on each other to complete repairs.

Having multiples of these spares would also constitute as a sort of disaster recovery, in case some natural disaster/war/accident/whatever happened to damage several of the springs simultaneously. The spares get swapped in and the damaged parts are fixed in turn and replaced as spares.

• Thanks for remembering the aethestic, even though I didn't stated it in the question and wasn't part of the goals ^^'. Remembering my old electricity lessons, I understand the parallel vs series advantages and issues. Though I'm left with a silly issue... which is I'll have to look at how mechanism experts switch from one spring/power input to the other x). Apr 16 at 22:29
• @Tortliena, happy to remember asthetics. Even though we engineer things, we also have to remember humans like pretty things. :-) I'm not sure you need to specify exactly how the springs are individually engaged, since the best scifi I've read usually leaves the "hard science" to a minimum and lets the reader/viewer make up their own mind. That said, it could be similar to switching gears on a bike or a car with gears, pulleys, chains, or something, then when the tension loosens due to an unwound spring, it changes gears, or whatever, which could also be spring driven. Apr 18 at 15:04

Something like a self-winding watch, but with the machinery driven by the wind rather than an oscillating weight.

• Oh yes, I think I see! I remember having seen one with this mechanism in their watch. Told me that the system alone isn't enough to make it last "forever", but if it is powered by stärke winds instead of feeble arms that'd change the story... Apr 16 at 22:37
• @Tortliena I had one half a century ago, and it worked fine for me. Apr 16 at 22:53
• Really? Then I guess they were just resting their arm on their armchair then :p. Apr 16 at 23:04
• @Tortliena I'm a physicist. I wave my hands a lot ツ Apr 16 at 23:45

(supposing there is always enough wind to move the clockwork forward !)

## Couple a wind meter with the clock's diaphragm-shaped air inlet

Ok I think you need a wind meter, and some construct to reduce the opening the wind blows through, to reach your clock propelling mechanism. Imagine some harmonica-like round opening, like the diaphragm of a camera.

To do that, you'd set up a wind meter, devise a way to transfer the force of the wind into that opening diameter.

Suppose you'd connect the wind meter mechanics in such a way, the round shape opening would change with the wind meter outcome. The only place you'd need to calibrate is where your wind meter compensates for the wind's force. As the air flows through the opening, the diameter should become smaller when there's a strong wind. There will be some kind of transmission between your wind meter and the size of the "aperture" round opening.. the result will be a constant airflow energy reaching your airflow-driven clockwork.

• except it won't work at all when there is no wind. "supposing there is always enough wind is a really unlikely assumption.
– John
Apr 15 at 1:37
• @John the assumption of perpetual winds was put as a first sentence (see above) and it was also mentioned in the comments on AlexP's answer (by me) but... no location was specified by Tortliena.. maybe Tortliena is from Iceland ? or Patagonia ? or Antarctica ? Some places on earth do have perpetual winds.. but indeed, you're right.. when the wind stops, the clock will stop, despite the stabilizing method I propose. I tried to answer the question marked in bold font, "how can wind input be made constant in order to accurately power a mechanical clock?" Apr 15 at 23:01
• @Goodies Environmental conditions are stated in the question : Oceanic climate, on the shoreline. Now I didn't tell a specific location, but oceanic climates share some traits regarding wind levels, just like beaches. Beach+oceanic tends to create good winds there, but if we take a look at a wind maps like this one, sometimes it just has to get boringly mild x_x'. Apr 16 at 22:22