The next morning started early for Cole. The human got up with the sun, and spent the first fifteen minutes cleaning up, and eating a brief snack, before he put on a blue track suit, and cross-trainers, then exited the training facility for his customary morning run. The princess’ had thoughtfully given Trixie a map of Canterlot to pass on to Cole, and the human had memorized it before going to bed the previous evening.
Now, with his rubber-soled feet lightly thumping on the cobblestoned streets, Cole felt his blood begin to pump harder, as he settled into a rhythm that let him eat up distance, and settle his mind on his intended lesson plan. Today, he would teach his class the basics of an Internal Combustion Engine, and why understanding how it worked was beneficial.
As the human continued his run, he heard the clatter of hooves approaching from behind. Sparing a glance over one shoulder, he saw a familiar blue coated unicorn rapidly catching up. Trixie was breathing hard, but still managed to ask the human what was up.
“Cole, what are you doing this early in the morning?”
“Going for a run, why do you ask?”
“A run? What for?”
“Humans need to maintain a certain level of physical fitness in order to remain healthy,” the human explained. “I run for a couple kilometers every other day to keep my heart and lungs healthy. I do physical exercise on the opposite days.”
It took the mare a moment to figure out why the human would need to exercise on a regular basis, but then the answer became obvious. “I get it! Because you have cars to go everywhere, you don’t need to walk all that much, so you have to exercise to stay healthy.”
“That’s part of it, yes,” Cole replied. “I also exercise because I like to. Being healthy means I have all the strength and energy I need to do my job well.”
The human and the unicorn ran on in silence for a few more minutes, until they came in sight of the converted stables again. Taking a breath, the human increased his speed. Trixie found herself falling behind, and struggled to keep up, but Cole steadily pulled away, transitioning from a loping run to a flat-out sprint. By the time she arrived at the gates, Cole was wiping sweat from his face with a towel he had left there for the purpose. The unicorn could barely speak when she finally arrived.
“How… did you… do that..?”
“Years of practice,” Cole replied, breathing hard, but much more easily than his panting running mate.
“Huh…?”
“You know how if you do something you get stronger, right? Same principal. That last part where we ran is called the “Kick”. Running like that helps increase stamina as well. It’s good for your body, and mind.”
“If you… say so…”
“Better go clean up, class starts in an hour,” Cole finished.
“…Right…”
With that, Trixie left, and went home to take a shower. Cole draped his towel over his neck, and made his way to his rooms to do the same. After cleaning up, the human set up his equipment in the classroom, a laptop and projector rig, for the day’s lesson.
Over the next 45 minutes, the other members of Cole’s class filtered in. Ditzy Doo landed first, toting a box of muffins, which Cole accepted with good grace, and set on a corner table in the classroom. Next came Balance wheel and Sergeant Stormcloud, followed closely by Earth Mover. Trixie arrived last, freshly scrubbed, but visibly still tired.
Standing up from his spot at the front of the room, Cole cleared his throat.
“Good morning, today we’ll begin the first in a series of lectures on automotive technology, and why understanding it will improve your ability to operate the vehicles you’ll be assigned later.”
Here Balance Wheel raised a hoof. “Am I to understand that we will be assigned vehicles like yours?”
“Not exactly,” Cole replied. “Your vehicles will be better suited to Equestrian terrain, and the existing roads. Later today, I’ll be taking you all for a ride in my vehicle, to get you used to the forces involved.”
With that somewhat ominous promise, Cole continued the lecture. Turning on the projector rig, he brought up a Video displaying the internals of an inline-4 engine. “Here we see the 4 phases of combustion:"
As the video played, Cole described what the class was seeing:
INTAKE STROKE
The piston starts at the top of the cylinder and begins to move downwards. Meanwhile, valves in the top of the cylinder (the cylinder head), called intake valves, are opened. The downward motion of the piston creates a vacuum, sucking in a mixture of gas and air through the intake valves. (We’ll talk about how the gas and air get there in a moment.)
COMPRESSION STROKE
When the piston gets to the bottom of the cylinder, the intake valves close. The piston moves upwards, compressing the fuel-air mixture and making it hotter and more volatile.
POWER STROKE
As the piston reaches the top of the cylinder, a spark plug, which is screwed into the top of the cylinder head, produces an electric spark. This ignites the fuel-air mixture, causing it to burn and expand and driving the piston downwards.
EXHAUST STROKE
When the piston reaches the bottom, another set of valves, called exhaust valves, are opened. The piston moves upward, pushing the spent exhaust gases out of the cylinder.
When the piston reaches the top, the exhaust valves close, the intake valves open, and the cycle starts again.
After letting the animation run to the end, Cole turned to the class. “So, does everyone understand so far?”
Surprisingly, sergeant Stormcloud was the first to raise a hoof. “I get it, but how can explosions that slow produce the power we used to escape the changelings last time? Looking at that video, I’d say you could only develop power as quickly as one of the local steam engines.”
“Good catch,” Cole replied, unsurprised at the thestral’s perception. “The animation you just saw has been massively slowed down. Each full cycle one of the cylinders completes is known as a “revolution”, and at its lowest idle, an internal combustion engine averages about 250-300 of these per cylinder, per minute.”
Here Balance Wheel raised a hoof. “I can see how that kind of power would make a vehicle it was built into go very fast,” he began. “But how would you keep that power in check? Wouldn’t the vehicle start moving the moment you started it up?”
“But it didn’t move when he started it up yesterday,” Ditzy Doo commented in puzzlement.
“An excellent observation,” Cole continued. “Basically, the large wheel you saw in the animation is called a clutch plate. It connects, or is a small distance from a second wheel of sorts, inside a case known as a “transaxle”. They’re not actually wheels, but the description fits. The case where these two wheels are located is filled with a special oil, and when the clutch plate moves very fast, the fluid drags on the second wheel, and makes it begin to spin as well. That motion is then transferred to the transmission, a series of gears that rotate at a set speed, and from there to the drive shafts, and on to the drive wheels.”
“When you press the accelerator pedal, the engine’s speed increases, and the two wheels move closer together, and more power is transferred. When you press on the brake, the two wheels are forced apart, and the engine slows down. All engines have an idle speed, and if the transmission is not in gear, the car will not move. The transmission contains several different gear sizes, or ratios. If you configure it one way, the car will go forwards. In a different way, it will go in reverse. If you set it to neutral, it won’t go anywhere, and in park, the transmission is locked.”
“If the car is in gear, it will move, just very slowly when the engine is at idle. Keep in mind that this is a massive oversimplification, we’ll go over diagrams for how this all actually works in detail later on.” Cole concluded.
“If I understand this, you’re saying the gear ratios automatically adjust when the car is in forward motion?” Balance Gear asked. “I mean, it only makes sense for them to, if only to prevent reaching the theoretical limit of the engine’s revolutions per minute too quickly.”
”It’s exactly as you say,” Cole confirmed. “As the vehicle accelerates, the speed the gears are turning will cause the next set of gears in a preset sequence to mesh, thereby allowing the same amount of power to produce a higher speed. Obviously, to keep the size down, and use fuel the most efficiently, your average 4-cylinder engine has only four forward gears, and one reverse gear. Along with the gear settings for neutral and park, this assembly is known as a 4-speed transmission.”
“How many speeds can a transmission have?” Earth Mover asked.
“How big of an engine do you have?” Cole replied. “On average, some large engines can have 10 or 12 forward gears, and 2 or 3 reverse gears, but these are found on very large engines. These kinds of gearing systems are used to haul very heavy loads.”
As the morning progressed, the ponies asked their instructor many more questions about how engines and transmissions worked. It was clear to Cole from the outset that his students were very intuitive, and they all asked intelligent questions. Later, around midday, the human called for a one hour lunch break.
As the class broke up, and the sergeant, Earth Mover, and Balance Wheel went out to their favorite eateries, Ditzy Doo and Trixie stayed behind with Cole, as the human went about preparing his lunch.
Cole had made a sandwich the night before, and simply went to his living spaces, and retrieved it from the solar-powered refrigerator he had set up the previous day. After that, it was a simple matter to return to the classroom, and set out his lunch at his desk.
Meanwhile, Ditzy Doo had set out her lunch, which she had brought along, and Trixie pulled an apple out of her saddlebags.
“So,” the unicorn asked the human. “When do we get to ride in the car?”
“Hold your- Just be patient,” Cole replied. “I had been planning to give those of you who haven’t ridden with me before a chance to ride along today after lunch.”
“Really?” Ditzy Doo asked eagerly. “I can’t wait!”
Cole had to internally cringe a little bit at the sheer eagerness the walleyed Pegasus displayed. “I have a question,” the human replied. “If I’m not being too forward, why would a person who can fly want to learn to drive? I mean, you have to be familiar with the fact that rapid movement through any medium requires …” Here the human trailed off, and gestured, not wanting to offend the mare.
“Depth perception?” The Pegasus finished.
Cole nodded uncomfortably. “I don’t mean to offend you, Miss Doo, but misjudging distances in a car can spell the difference between a close call, and the lives of you and your passengers/cargo.”
“I understand,” the Pegasus replied slowly. “My strabismus is pretty obvious, and it makes looking at things a little hard, but if I concentrate, I can keep both eyes on target, so it’s not really an issue. Plus, I’ve learned to be able to read two things at once!”
“…Ok, then,” Cole replied with a small amount of nervousness at the mare’s casual reply. “I apologize if I’ve offended you by bringing it up.”
“It’s OK, you’re just doing your job.” Ditzy reassured him. “And you were much nicer about asking than my old flight school instructors were, so thanks for that.”
“You’re welcome,” the human finished.
Trixie had busied herself with a textbook through the entire awkward exchange, and flicked an ear towards the stable entrance, as the sounds of the others returning began to filter in.
“Looks like the others are back,” she commented briskly.
“Ok then,” Cole responded, dusting crumbs off his shirt, and wadding up his trash, before tossing it into a trashcan by his desk. “Next up, more on the inner workings of a typical car, and your first practical driving experience”