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Maxed Out: From Steam Engines to Wind Walkers
November 16, 2011 |Estimated reading time: 6 minutes
Ever since I was a young lad, I’ve been interested in spaceships and robots. In particular I’ve been interested in the electronic systems that were used to control them. Sad to relate, I really didn’t give much thought to the mechanical side of things. This is a shame, because in recent years I’ve come to appreciate mechanical systems as things of beauty and a joy to behold, if you know what I mean.
For example, my degree is in control engineering. This was based on a core of math with “surrounding subjects” of electronics, mechanics, hydraulics and fluidics. Now, when someone says “control system,” my knee-jerk reaction is to assume something relatively modern; I also assume an electronic realization in general and a microcontroller-based system in particular.
In reality, of course, control systems date back to antiquity. Originally, all such systems were mechanical in nature. The one that immediately springs to my mind is the centrifugal “fly-ball” governor, which was used to control the speed of an engine and prevent it from racing out of control.
Figure 1. A centrifugal fly-ball governor.
The first such governor was designed by James Watt as far back as 1788. The device shown in Figure 1 is used to control a steam engine, but later versions were used to control internal combustion engines and variously fueled turbines.
The idea is that – in addition to its main task – the engine also causes the governor assembly to spin. Centrifugal force causes the balls to move outwards and upwards against gravity. If this motion goes far enough, it causes the lever arms to pull down on a thrust bearing, which moves a beam linkage, which reduces the aperture of a throttle valve, thereby controlling the rate of the working fluid, which would be steam in this example or fuel in the case of an internal combustion engine.
As an interesting tidbit of trivia, the first formal analysis in the realm of what we now know as control theory was performed on the centrifugal governor by the physicist James Clerk Maxwell in 1868. This described and analyzed the phenomenon of "hunting," in which lags in the system could lead to overcompensation and unstable behavior.
Oh no…I can feel myself drifting into “rambling mode” again as different memories begin to surface. Talking about steam engines reminds me of one I saw last year when I travelled to my hometown of Sheffield, England. While I was there we visited an industrial museum where we saw a monstrous steam engine.
Figure 2. A steam engine built circa 1900.
As I recall, this was built sometime around 1900 for use in a steel rolling mill (Sheffield was famous around the world for its iron and steel). You must have seen television programs showing a massive slab of red/yellow/white-hot medal being rolled back and forth as it is gradually flattened and stretched out. Well, that’s what this engine was used for.
The amazing thing is that it still works more than 100 years after it was created. In fact they power it up once a day for any visitors to the museum. The guy in charge (you can see him in the picture above) starts things off slowly. I’m not sure what he does, but the three massive pistons gradually start to rise and fall and the flywheel slowly starts to turn.
But, as soon as you’ve been lulled into a false sense of security, the engineer suddenly ramps this beauty up to full speed. Within a couple of seconds the pistons are pounding (the noise is tremendous) and the flywheel, which must be at least 20 or 30 feet in diameter and weigh how many tons, is spinning faster than the eye can see.
I cannot tell you how impressive this all is. What is even more impressive is when the engineer throws things into reverse – remember, this engine was designed to roll huge bars of steel back and forth. Now, I know you aren’t going to believe me, but I swear that the whole engine – which was running at full pelt – stopped and reversed within a couple of seconds. All I can say is that the whole thing left me breathless.
And thinking of Sheffield’s history reminds me of when I was about three years old. Both my father and my mother worked (it was unusual for women to have jobs in those times), so I spent the days with my grandmother. In the evening we would walk hand-in-hand from her house to my parents’ house, which was about three miles away. In order to get there we would pass through a maze of little alleyways that wended their way through an industrial estate comprising lots of little engineering companies.
Figure 3. A factory in Sheffield, England, circa 1910.
The picture in Figure 3 is from a factory in Sheffield circa 1910, but this is just what I saw when I peered through cracks in the wooden doors to the factories I walked past with my grandmother years ago. But that’s not what I wanted to talk to you about…
Behold the Wind Walker
What I really wanted to talk about was an amazing mechanical toy that someone gave me. Theo Jansen (born in 1948) is a Dutch artist who has become famous for creating kinetic sculptures that resemble skeletons of animals and that are able to walk on sandy beaches using the wind as a source of power (Click here to see a video on YouTube).
Constructed as intricate assemblages of piping, wood, and wing-like sails, Jansen's creatures are constantly evolving. Some of the creatures are able to store air pressure and use it to drive them in the absence of wind. Some of the more sophisticated creations are able to detect once they have entered the water and walk away from it, and one species will even anchor itself to the earth if it senses a storm approaching.
A friend of mine in California saw a model of one of these creatures, and he surprised me by sending me a kit. When I opened the box I found a plethora of plastic parts that was at first a little daunting. However, the instructions were clear and within a couple of hours my little “Wind Walker” was walking furiously.
Figure 4. My little wind walker.
The final result is very, very impressive. The propeller is geared down to the extent that you can gently blow and the beast will start to walk. The articulation of the legs is so sophisticated that you can watch this little scamp walk for ages without ever getting tired of it.
Click here to see a video in which you first see me playing with one set of legs, and then we see the full beast walking. One of the guys in the office uses a small fan to provide a constant wind.
Well, I would stay and chat longer, but I’m afraid we had a water leak at our house and the wood on the kitchen floor has buckled up. I have to meet with a builder who is going to make me cry when he tells me how much it is going to cost to have everything fixed.
So I must away. Until next time, have a good one!
Clive (Max) Maxfield is founder/consultant at Maxfield High-Tech Consulting. He is the author and co-author of a number of books, including Bebop to the Boolean Boogie (An Unconventional Guide to Electronics) and How Computers Do Math featuring the pedagogical and phantasmagorical virtual DIY Calculator. To contact Max, click here.