by Pepper White
"Pepper White."
"Oh yeah, you're the new apprentice. I remember Professor West mentioning something about you coming along after Christmas. I tell you one thing, Cap'n, we're gonna be suckin' some wind on this job."
I liked the way he said we. "Got any suggestions on where to start?" I asked him.
"Showah. Take it apaht. Get yuh hands on the soul of that old rapid compression machine. Let's bring the A-frame hoist in here and we'll take the front end off it. We gotta let it know who's boss."
Not even an hour into the project and I was already learning one of the most basic concepts in heavy industry: rigging, or moving big heavy objects around without dropping them on your foot or wrecking your back or sometimes doing both. That must be why they call it heavy industry.
"And remembah, Cap'n," Nick said, "you'll get there a lot fastuh and safuh if you keep the Lawd as yah pahtnah."
We took the A-frame hoist from the spare parts area behind the chain-link fence across from my cell. Glenn Miller stopped playing, and the announcer said, "The music of your life." The music added to the lab's archaic feeling. We all know that engines work, so what's left to find out about them? The hot stuff was in the electronics labs around the comer. That's where the technology is high and not mature. But what good is electronics without something real to make or control? Such as a rapid compression machine.
A real four-stroke diesel engine in a real car or truck has a piston that moves up and down two times per engine cycle. Each one-way trip the piston makes up or down the cylinder is called a stroke. Figure the piston is at the top of the cylinder.
The volume of the cylinder is very small at that point, and a valve (called the intake valve) opens to let air in as the piston moves down. This is called the intake stroke (the cylinder takes in air). When the piston is near the bottom of the intake stroke, the intake valve closes and the piston moves up and compresses the air that's trapped in the cylinder by the closed valve. This is the compression stroke. The "compression ratio" is the volume bounded by the piston and the cylinder at the beginning of the compression stroke, divided by the same volume at the end of the compression stroke.
When the piston is near the end of the compression stroke, the fuel injector squirts diesel fuel into the cylinder. The fuel evaporates and burns, and the heat generated by the burning fuel raises the pressure even more and pushes the piston down. This is the power stroke.
Once the piston bottoms out, the exhaust valve opens and the piston pushes the burned fuel out of the cylinder to the tailpipe. This is the exhaust stroke.
Then the intake valve opens and the cycle repeats itself. That much I remembered from the science report I paraphrased from the encyclopaedia in ninth grade.
The rapid compression machine would simulate the compression and combustion parts of the cycle.
Before using the A-frame, I made a sketch in my brand-new lab notebook to record how we rigged it. If anything went wrong, we could refer to the sketch to analyze what happened. If our work was successful, the sketch might be helpful for future generations of RCM students.
Nick agreed with my setup and we went to work. The A-frame in place and the chain fall wrapped around the cylinder, he said, "OK, Cap'n. Go get a wrench outa my tool box and undo the bolts. I'll hold the chain fall steady."
The bolts loosened with hard tugs and some body weight. Nick tightened the chain just before the last one loosened.
"There's a piston in the front cylinder that we gotta pull the cylinder offa," Nick said. "Here, use this screwdriver to get the cylinder started."
I wedged the screwdriver between the two flanges and eased them apart. As the cylinder moved forward a chrome shaft appeared about a quarter of an inch at a time. Nick and I slowly worked the cylinder away from the rest of the machine.
Two feet out, Nick said, "Easy now, Cap'n, we got just a couple more inches. We don't wanna bend that shaft now. It'd slow things up for me to have to make a new one."
Gently, slowly we freed the cylinder from the piston, leaving the shaft unscathed. "Let's bring this thing onto the workbench," he said, and we walked the A-frame and the cylinder opposite the bench.
"You hold it, Cap'n, while I hoist her up," Nick said, pulling the free end of the chain up a foot or two at a time. Within a few minutes, he had lifted the cylinder to the level of the bench; then we straddled the bench with the A-frame and lowered the cylinder.
"How's that thing work?" I asked Nick, pointing to the hoist.
"It's just the pulley principle," he said. "It's sorta like theyah's a lot of pulleys in theyah. I pull on one end of the pulley and the thing I'm trying to lift goes half as fah. Wasn't it Aristotle who said that if he had enough pulleys he could move the world?"
I wondered whether Nick had his facts straight. The general idea sounded plausible, though. "I thought that stuff all started with the industrial revolution, though."
"No, Cap'n, this kind of thing's been around for a while. How do you think they built all those cathedrals in the Middle Ages? They sure didn't carry all those rocks to the top," he answered.
He had a point. The pulley and the lever had been around for four, maybe five thousand years. They were the first steps, along with the wheel, in using the laws of nature to magnify force by shrinking distance.
"Well, that's enough for now, Cap'n. Time for my roll. You want anything from the coffee shop?"
"No thanks, Nick. I think I'll stay here and try to figure out what these pieces do."
"Okeedokay," he said. "Say, Peppah, I used to teach a machining class. It might help you get your feet on the ground if we spend some time each day going over the basics."
"Thanks. I might take you up on that." The Lone Ranger had Tonto; I had Nick.
Nick went outside and the noise from the Wright Brothers' wind tunnel next door sounded like a squadron of B-17's on their way to bomb Dusseldorf. The radio played "Don't Sit under the Apple Tree with Anyone Else but Me." I half expected to hear an ad for war bonds.
If you don't know what you're doing, the first thing to do is to try to look like you know what you're doing. That buys you time. And so I started cleaning up the cell. I removed the yellowed sheet of paper from the tank and scraped the old masking tape away with Nick's screwdriver. I cleared all the old pieces of junk off the available bench space. Then I made a list of the items in the lab as one by one I put them neatly on one of the two workbenches. Some of the devices would never have another use before they either were reborn as a Toyota or went back to iron ore in a landfill somewhere. Others might be adaptable to the new experiment; salvageable, they might save days, weeks of time.
I found an old blue lab jacket with "Don" on the name patch. I put it on. Under one of the benches I found an old pile of notes from West's thesis. They were disorganized and it made me feel a little better to know that for all his surface order there had been at least some chaos in his life at one time.
All the metal was mounted on a 6-inch-thick steel pad with slots running from one end to the other. The slots furnished a place to bolt down all the heavy stuff. I started to clean the little bits of metal out of the slots, but that was too hard and probably a waste of time so I just dusted off the top of the pad. My high school's "shop" teacher, an iron worker, might have had some tips for me if he were still alive.
Five-thirty came quickly. Nick and I washed our hands with Boraxo and he took off the baseball cap, showing a completely bald head except for the gray around the edges.
"See you tomorrow, Cap'n," he said. "Be fresh and ready to learn how to machine."
"Will do, Nick. Have a good one."
7:45 P.M. After my swim-it did wake me up-I saw Frederick Weare, the rock crusher who didn't fund me, in the locker room.
"Have you found funding yet?" he asked.
"Yes, as a matter of fact. I'm working on the Rapid Compression Machine in the Sloan Auto Lab."
"Good for you," he said. "What exactly is the scope of your investigation?"
"Um hmmm," he nodded again. He didn't ask any more about diesel combustion because that was outside his realm of expertise. "What kind of instrumentation will you be using?"
"I don't know exactly yet-see, this was my first day and I'm just trying to get oriented," I answered.
"Well, it sounds like a lot of fun. Good luck with it."
Thanks, Fred. Maybe we'll co-author a paper some day.
8:15 P.M. He who fails to learn from history is doomed to repeat it. The theses of experiments past are on the eighth floor of the Barton Engineering Library. Chemical, electrical, civil, nuclear, mechanical engineering. Rows upon rows of black-bound typewritten pages, each with three signatures on the front-author, adviser, graduate department chairman. The name of the author is written on the side in skinny white capital letters, together with the year of completion, as far back as the 1940s. Any further back than that and you have to go to microfiche.
I started with West, Sc.D. '71. There were some color pictures of glowing yellow flames. An Sc.D. is a doctor of science, which makes more sense than a Ph.D. since auto mechanics is a lot closer to science than it is to philosophy. Only MIT, Stanford, Cal Tech, and a few other choice schools offer the option of Sc.D. instead of Ph.D. on the diploma. It enables the hyperelite to recognize each other without stooping to ask where they earned their credentials.
I looked in the list of references in the back of West's thesis. He referred to Pyra, '68, whose B.S. was from the University of Prague. Pyra didn't have any pictures, just graphs. I put them both in my stack. Pyra referred to Nayak, '63-B.S., University of Cairo. Nayak had lots of graphs, too, and he referred to Rathle, '5 9. Rathle had received his B.S. from the University of Alexandria, Egypt, in 1957. Rathle had built the RCM. My apparatus and I were both twenty-five years old.
Rathle's diagrams made the scales drop from my eyes. The machine had three chambers. The front cylinder, where combustion took place, was what Nick and I had removed earlier in the day. The back part of the front part had "nonreturn pawls," which caught the shaft as it went to the end of the stroke and kept it from bouncing backward or being pushed backward by the pressure of the exploding diesel fuel. The middle cylinder had compressed air and a piston four times the size of the front piston. The bigger area enabled the whole shaft to move forward, even when the combustion chamber's pressure was much higher than the pressure in the tank.
The back cylinder had various-size rings in it and was filled with transmission fluid. A piston on the shaft in the back cylinder would slow down the whole shaft to make the compression stroke similar to that in a real engine, where the piston is attached to a rotating crankshaft.
From Rathle back the references were in journals-Taylor, 1948; Selden, 1937; Rothrock, 1932; Moore, 1922; Falk, 1906.
Falk's machine was a vertical tube filled with hydrogen. His shaft had a lead weight on top, and the piston had rope piston rings to seal the gap between the piston and cylinder. He dropped the weight and measured the temperature at which the gas combusted. That first version was simple, almost trivial, but essentially the same as my large gray mass of metal.
Falk referred to LeChatelier, as in Le Chatelier's Principle (1888) : When an external force is applied to a system at equilibrium, the system adjusts so as to minimize the effect of the applied force." Go with the flow.
I looked up Diesel in Encyclopaedia Britannica. Rudolph Diesel (born 1858, died 1913), German thermal engineer, was also a distinguished connoisseur of the arts, a linguist, and a social theorist. While at the technical school in Augsburg, he saw a demonstration of the ancient Chinese fire stick. The fire stick, dating to 1000 B.C. or earlier, is like the bicycle pumps that fit on the frame of the bicycle. You put a dry leaf or a dry tindery piece of wood in one end, close it off, give the pump one good rapid compression, and pow, fire. From that demonstration came the idea for his engine.
I felt I was in good company, carrying on a tradition, a legacy.
Diesel developed his engine, amassed great wealth, invested poorly, and for reasons unknown "apparently fell" from the deck of the mail steamer Dresden en route to London.
Wednesday
"This heeyuh's a micrometer," Nick said. "You take this and you measure how big something is, in thousandths of inches. The real fancy ones go down to ten-thousandths, but we'll just do the thousandths."
A thousandth of an inch seemed incomprehensibly small to me-how could anything be measured that precisely? How could anything matter on that scale?
Nick continued, "You hold the micrometer like this, see, and you put the two pins just apart from each other on the workpiece." The workpiece was a bar of metal mounted in the lathe. "You want to make the two ends of the micrometer just slip off the workpiece and then you read it. That'll tell you how many thousandths you still need to take off. There's a little rust on this bar, and we can take that off by either pouring Coke over it or turning it down."
I wondered whether there were any connection between the machinists' expression for scraping the skin off a piece of metal and being turned down as a person.
"First we gotta put the tool in the tool holder," Nick continued. "This here's the cutting edge," he said, holding the inch-long piece of metal and pointing out the sharp side. "We're going to bolt it into the machine and then bring it just up to the workpiece by turning the cross-feed handwheel here."
The handwheel had gradations in it so that one revolution of the handwheel made the block of metal to which the cutting tool was attached move a tenth of an inch toward the workpiece. The dial on the knob had 100 hash marks around the outside. The hundred hash marks dividing up a tenth of an inch allow you to move the cutting tool a thousandth of an inch. Like the micrometer, the device magnifies space.
Nick advanced the tool to the workpiece and then moved it forward five thousandths. The tool cut a little sliver through the rust, showing the pure, clean steel underneath. "Now, Cap'n, turn this crank nice and slow and you'll take five thousandths off the whole rod. Let's put a little cutting oil on there first, though."
He put a few drops from the oil can that looked like the kind engineers use to lubricate their trains. The oil smoked when the tool made contact, and I turned the crank slowly and the sliver made a continuous thread of steel as I removed the thousandths from the length of the shaft.
"Very good, Cap'n. Now bring the tool back and you can take some more thousandths off for practice." I took ten more thousandths off and the rod was noticeably smaller on the length where I removed the fifteen thousandths.
"That oughta be enough school for today, Cap'n. I brought in this book for you to take a look at," Nick said, handing me the grease-marked manual that he'd used in his first machine shop class-Practical Machining.
The cover illustration showed workers in the sixteenth century operating a foot-powered lathe. First the brick, then the pulley, the fire stick, now the lathe-simple ideas have been around for a very long time.
I walked back to my cell and met Mary on her way into the shop. She wore a lab jacket with her name written on it, and above her name was written "Dynatech."
"Hi, Don," she said, referring to my lab jacket.
"Hi, Mary. What brings you to these parts? I thought you were still a teaching assistant."
"I got an R.A. with West, just like you," she said. "I'm working with Paul Kahn on the Caterpillar engine at the other end of the lab." She looked at the book Nick lent me and said, "Taking up a trade?"
"Let's just say it'll be my recession insurance."
"If you want recession insurance you ought to become a plumber. Machinists will be the first to get laid off."
"Yeah, well, the more versatile I can be the better. Do you want to take a look at my cell?"
"Sure," she said.
I opened the doors. She was impressed by the brown paper on the workbenches an
d the neatly laid out equipment and tools. "It looks very professional," she said. "What's that crack up at the top of the wall there?" she asked.
"The machine has taken part of the building with it every time they've done a test in the past. The forces released are like those from a small cannon," I answered.
"Whoa. Be careful. I hope nothing blows up while you're in here."
The danger hadn't yet occurred to me. Then I remembered West's story about the physicist and the laser. And Matt Armstrong had told me that formal occupational safety at MIT is fairly lax because graduate students are supposed to be professionals, and professionals take care of themselves.
"I'll be careful. Can we take a look at your cell?"
"Sure," she answered, as we walked to the north end of the lab.
I read the signs on the doors of the other test cells: "Constant Volume Combustion Bomb: Sponsor: Department of Energy"; "Square Piston Clear Engine: Sponsor: Industrial Consortium"; "Clear Cylinder for Study of Piston Ring Motion: Sponsor: General Motors." I asked Mary whether she knew how these projects got funded.
"There're several avenues. Some of these companies have research budgets that they spend on universities. Half the people in the automotive industry's research departments have degrees from here, and they remember their buddies when they give out the grants. Some of the sponsors expect real results, things that will directly apply to engines, but mostly they're after advances in concepts and understanding of the processes. They get that in the papers the professors and students write that are based on the research. Plus, they get well-trained researchers who can hit the ground running developing products for GM, Chrysler, or Ford. Here we are."
She opened the door to her cell, where there was a blue, newly painted engine with about twenty wires connecting it to a computery looking thing in the corner.