This is an overtold joke, but please bear with me for a moment
Two engineering students were walking across campus when one said, "Where did you get such a great bike?"
The second engineer replied, "Well, I was walking along yesterday minding my own business when a beautiful woman rode up on this bike. She threw the bike to the ground, took off all her clothes and said, "Take what you want."
The second engineer nodded approvingly, "Good choice; the clothes probably wouldn't have fit."
And why am I telling this joke? Because I just found this.
If you've turned on your television lately then you've probably noticed that the Chia Pet and George Foreman grill commercials are back. That can only mean one thing; it's holiday shopping season.
If everyone on your list already has a salad shooter and you don't want a repeat of the sock and sweater debacle of last Christmas then here's another option. The Wenger Giant Swiss Army Knife (TM).
Now I like pocketknives, and I frequently carry a Swiss Army Knife (usually have a Victorinox) but this is hardly describable as a pocketknife. With 85 implements the knife (if you can even call it that) measures almost 9" wide, and I doubt you could comfortably fit it into a pocket.
Basically, it is all of the Swiss Army knife tools shoved between two red scales, and while many of the tools are quite useful in certain situations, it's ridiculous to have them on the same knife. Really, how many times do you need to have a golf shoe spike wrench, a 12/20 gauge choke tube tool, bike chain rivet tool, and a watch case opening tool all at once?
Still, if you absolutely insist upon having the biggest Swiss Army Knife around you can get one of these for $1200...if you can find one. The Wenger website says they're out of stock. Apparently some people actually are willing to spend twelve hundred bucks on a pocketknife that's too big to carry and too unwieldy to use.
It's hunting season, so I'm using that as a flimsy excuse to post this joke.
Three statisticians went deer hunting.
They spied a deer in the woods. The first statistician shot, and missed the deer by being a foot too far to the left. The deer was alarmed but froze in place, giving the second statistician a shot. He missed the deer by being a foot too far to the right.
Today I thought it would be appropriate to share the rest of my pictures from the last trip to Australia. These didn't really fit with the mood of the other pictures, but now that it's Armistice Day (Veterans day if you prefer the new label) I think it's time to share these pictures.
Just a mile or two away from Flinders Street station, located in a large park where the bustle of the city seems to disappear, you will find the Shrine of Remembrance.
The shrine was built between 1928 and 1934. It's original purpose was to show gratitude for the thousands of Victoria residents who served and died in 'The Great War.' As time marched on and the war of 1914 became known as World War I (thanks to the dawn of World War II) the shrine came to be a memorial for all who served in the armed services. More conflicts and places were carved into the stones of the shrine, and other memorials were erected for various conflicts and branches of the armed services.
The shrine is open to the public from 10 to 5 every day except Good Friday and Christmas so that anyone can tour the grounds and the interior of the shrine itself. A long walk up the steps in front will lead you to this quiet sanctuary.
Along the walls of the sanctuary you will find images of soldiers in action during WW I carved into the stone walls. In the middle of the room is a stone, set in a recess in the floor, with a brief inscription. Every year on November 11 at 11AM, a point of light from the skylight above moves across the stone and highlights the word love.
Below the sanctuary is an even more somber feature of the shrine; the crypt.
The walls are lined with bronze tablets listing the military units involved in the great war and all around the ceiling hang the regimental colors of these units. The feature in the center of the room is the father and son statue, placed there to honor two succeeding generations of Victorians. The inscription below reads,
THESE FIGURES OF FATHER AND SON HONOUR THE COURAGE AND SACRIFICE WHICH LINKS TWO GENERATIONS OF VICTORIAN SERVICE MEN AND WOMEN WHO SERVED AND DIED IN THE WORLD WARS 1914-1918 AND 1939-1945
I could say more, but you would learn more by visiting the shrine's website and reading more about it there. And I hope, as you read about the shrine and look at the photos that you can take a moment to think about the sacrifices made by the men and women of the armed services around the world.
I mentioned in my 'Powerhouse' post that steam power helped to free people from the restrictions of the waterwheel. Recently I had the opportunity to visit a site where the power of water was very successfully utilized for many years. So successfully in fact, that it was being used past the heyday of the stationary steam engine.
The Aldie Mill was constructed in the early 1800s, and was soon followed by a town bearing the name of Aldie Virginia. The mill would buy local grain crops and grind them into meal and flour, or grind grain for the farmer himself for a fee (which was usually a percentage of the grain.) Since the area relied heavily upon agriculture, the mill eventually became quite a success. So successful in fact that it did not close until 1971 after being owned by six generations of Moore family.
What makes this mill a little unusual is the waterwheel, or rather, waterwheels.
Unlike many mills, this one had two waterwheels instead of just one. This gave the miller more power at his disposal. At one point the mill was operating 5 grist mills at the same time. But before I get too far ahead of myself let's take a moment to look at the process from the beginning.
When you want to use a waterwheel what's the first thing you need? Water of course.
This mill pond has been consructed along the course of a small waterway, so that a sizable quantity of water can be stored.
A wooden gate limits the flow of the water so that the mill can be shut off. In this case the gate is mostly hidden because the pond is full and running over the stone spillway. From there, the water flows down a pipe to one of two control gates which allow individual control over each wheel. I suspect these are more recent than the mill itself, but they still aren't new.
Inside the mill, the miller opens the control gates to start the waterwheels. These monsters (approximately 18' in diameter) are so heavy that it's necessary to fill 3 of the troughs before you see any rotation. A large shaft runs through the wall of the mill, connecting the waterwheel to one of the large gears inside which turns a gear on the shaft connected to one of the mill stones.
These gears probably replaced a system of wooden cogs with a similar configuration.
Up above that last picture you will find this, the center of activity.
Here, the miller would load grain into the hoppers, either manually from sacks, or by use of the mills built in elevator system, which was capable of conveying grain between all three floors of the mill. The mill would be fed through a hole in the center of the upper stone, and then crushed between the two stones.
This was accomplished by means of multiple grooves cut into the face of the stones. These grooves create a scissors like action which actually cuts the grains. Typically these grooves can also be shaped to limit the travel of the grist so that the smaller particles travel toward the outer edge of the stones. In this case, the stones were quarried in France and shipped, in multiple pieces) the the united states where they were assembled and held together by a large iron band.
The fine particles which escape from the stones, now meal or flower, are funneled down into the basement where they can again be conveyed upstairs. When the grinding is complete, the flour or meal is then conveyed through this hollow beam to the granary next door for storage and sale.
One of the fascinating things about this mill is that it has, at some point, been refitted with newer equipment. So far, the equipment has been directly driven from shafts and gears. A line shaft type system was also used.
Here you can see the input from the other waterwheel, which is conveyed, by a set of gears to the large pulley seen peaking out of the hole in the floor in the phot below.
That pulley would have a large belt on it which would be used to turn another, smaler pulley. The smaller pulley would be connected to a large shaft or set of shafts with multiple pulleys and belts for running various machines around the mill. In later years, this would have served a set of roller style mills similar to these.
These roller mills provided a more efficient system of grinding because rather than using large, heavy rotating parts to grind the meal all at once, the roller mills use small, high speed rollers to cut and crush the grain. This is done in multiple stages rather than trying to do the work all at once as was the case with stone grinding.
The Aldie Mill eventually succumbed to the ravages of time. For a while it was kept running by using a tractor to drive the line shaft system, but it would have been impractical to continue running the equipment in such a manner. The site has now been restored so that the mill is partially functional.
It is open on the weekends for tours, and occasionally it is run for the enjoyment of the visitors.
Please pardon the interruption folks. Not only have I been away from home, but apparently my monitor bit the dust recently. The good news is that it was under warranty and is being replaced soon. Until then, I'm on laptop duty for a while.
I said that I would be posting more items about the Old Threshers festival in Mt. Pleasant Iowa, but in trying to put together a logical set of posts I have found that, there’s so much to talk about that I’m going to have to divide things up considerably. To that end, I’m making an effort to put together multiple posts, mostly centering around the old technology found at Old Threshers. It should end up being a series of more than a dozen posts, but it will take a while to write all of them.
I’ll start things off with stationary engines.
The concept behind a stationary steam engine is fairly simple. Steam is generated in a boiler and then piped to an engine where it is used to push a piston down a cylinder. The piston is attached to a push-rod, which turns a crank attached to a flywheel and pulley. Just like that, you have a nice smooth power source to power your machinery.
Not quite.
The problem is, if you just pipe steam into a cylinder, it will push the piston to one end and stop. If you want to push the piston back, you can seal off the other end of the cylinder and pipe steam in on the opposite side of the piston. That’s still not going to help though because if you pipe the same steam pressure to both ends of the cylinder, the pressures cancel each other out and the piston doesn’t move.
What’s really necessary is to make the system work is a set of valves that allow steam to enter one side of the cylinder while allowing it to escape from the other. Unless you want a worker next to the engine all day opening and closing valves, you need a valve gear mechanism.
In its simplest form, a valve gear mechanism is just an eccentric on the crankshaft connected to a pushrod that moves a plate or piston back and forth, that directs the flow of steam and exhaust. This would work for some things, but doesn’t allow the engine to be run efficiently in reverse without stopping to modify the engine setup. After you’ve figured out how to reverse the valve operation there’s another problem.
If you want an engine to run efficiently, you need the ability to adjust the length of time the steam valve is open. Simply leaving the steam valve open for the entire length of a piston’s stroke will give you tremendous power, but it also uses plenty of steam. To reduce the steam consumption, you open the valve briefly at the beginning of the stroke, then shut it again, using the expansion of the steam to move the piston, rather than just the raw pressure supplied from the boiler. Of course the amount of power you need can vary considerably, so it’s necessary to make adjustments to the valve timing while the machine is still running. There are multiple versions of valve gears that deal with this, which were adapted to various applications like steam locomotives and tractors.
After you’ve solved those problems, there’s one more little detail, how do you keep the engine running at the same speed all the time when the load on the machine is being varied constantly? This is where a device called a governor comes into play. It’s a device that creates a feedback loop so that the speed of the engine has an impact on the power applied to each stroke.
In the picture above you will notice a tan belt running from behind the flywheel to a small pulley on the left hand side of the engine. This pulley is geared to something that looks a little like what you’ll see in the next picture.
This is a simple theoretical design. It’s not perfectly accurate to any one device, but it at least similar to what you will see on most steam engines. There are two weights on the end of link arms, and as the assembly rotates, these two weights move further outward until they balance they reach equilibrium with the force supplied by the counterweight. The rod traveling through the middle of the assembly is free to move up and down as the weights and counterbalance push it, and it is this movement that controls the application of power. There are many versions of this type of governor with seemingly endless variations of springs, weights, and linkages, but they all come back to the utilization of centrifugal force on a counterweight.
Even the simplest little engines, like this one, have some sort of governor to control their speed. On this one, you’ll see it located right on top of a valve on the steam supply line.
As always, there are a few more unusual versions of this centrifugal governor design. Here’s an example of an un-restored skinner engine which actually mounts the governor assembly inside the flywheel.
As before, 2 counterweights are spun around and pulled outward from the center of rotation. In this case, they are opposing a force supplied by a large set of leaf springs which are also mounted inside the flywheel. It is also worth noting, that while the previous two examples we’ve seen controlled the engine’s speed by controlling the steam supply, this governor actually changes the motion of the eccentric which controls the amount of travel of the slide valve.
As time went by, the steam engine was refined to get more power for less energy. Valve designs evolved so that valves opened very quickly and precisely in order to get a quick burst of steam into the cylinder, allowing for considerable power at high speeds. As this video shows, there are plenty of moving parts used in some of the more complicated valve systems.
In this case, there two intake valves (located on the top of the cylinder) and two exhaust valves (on the bottom) being driven off of a complex cam system. Two dashpots (seen in the floor) are employed to control the valves as they open and close so that they can be moved quickly with minimal shock.
Another advance in steam engine efficiency was the introduction of double (possibly even triple) expansion steam cylinders.
If you look at this picture you’ll notice that this corliss engine, the ‘Marshall’ manufactured by Allis Chalmers, happens to have two cylinders, one of which is much larger than the other. The reason for this is that even after a quantity of steam is used once, it usually has some remaining potential for expansion. The problem is, this ‘used steam’ occupies a much greater volume than it did originally and it provides much lower pressure than before, so in order to get similar amounts of force, you need to have a larger surface area for it to push against. With this in mind, you can understand how it is appropriate to first send steam to the small cylinder and then send the exhaust from that cylinder to the larger cylinder.
This increases efficiency by getting more energy out of a given quantity of steam, but it also adds considerably to the complexity of the machine. I think this is best illustrated by this next picture.
I really love that view of the engine because most of the parts you see in the picture are moving, so watching it run is quite impressive.
Eventually these beautiful behemoths would be replaced by other power sources, but that doesn’t mean they become any less interesting.
I never capped off my last trip overseas, so I figured I should post a few pictures from Australia.
As usual, I spent most of my time in the small town of Ballarat. I've already posted several pictures from there. I could post a few more pictures from there, but it would only be more of the same. I ended up catching a train from Ballarat to Melbourne.
It was a nice chance to relax and watch the Australian countryside.
I ended up in a Hotel in Melbourne near the Flinders Street Station
This area is apparently the place to meet in Melbourne. It has considerable train traffic as well as a couple of tram stops right outside. In the evening the entryway to this place was absolutely packed with people. Chances are, most of them are intent upon going to the river walk area.
Along the river in Melbourne there's a long stretch that's filled with cafes, restaurants, pubs and shops. It's a bit quiet in the morning, but it's swarming with people in the evening. As is usually the case in Melbourne, there's also a considerable amount of green space left open so that the area doesn't seem exceedingly crowded.
Of course if you want to get a tour of Melbourne without having to walk, you can hop one of their 'City Circle' trolleys. These old style trolley cars can take you around to see the attractions of Melbourne.
I have to say, I'm not too crazy about crowded cities, but Melbourne is really pretty nice.
This area is apparently the place to meet in Melbourne. It has considerable train traffic as well as a couple of tram stops right outside. In the evening the entryway to this place was absolutely packed with people. Chances are, most of them are intent upon going to the river walk area.
