Cars: How do they work?

December 31, 2014 2:24 AM

You wonder how your car works, you say? Let the wisdom of the ancients guide you. Start with springs and shock absorbers (1938).

Transmissions (1936)
Brakes (1935)
Gasoline engines (1941)
Water cooled engines (1936)
Hydraulic power steering (1956)

And featured two years ago on MeFi: Differentials (1937)

And here is a subject you should not reference the ancient world much on: Automotive safety (1935).

posted by Harald74 (41 comments total)

Dude, I have a Prius. I have not one clue as to what's going on under the hood.
posted by SPrintF at 2:33 AM on December 31, 2014 [3 favorites]

I just watched that differential video the other day; loved it! The inclusion of a bunch of motorcycle formation riding at the beginning was a nifty touch, if only barely related to he topic.
posted by TedW at 2:35 AM on December 31, 2014

Hmm, the last link is still quite relevant, it emphasises safety being largely dependant on the skill of the driver. Unless of course, you think that is too much to expect.
posted by epo at 2:36 AM on December 31, 2014

Dude, a Prius has everything on that list.
 
posted by Herodios at 3:48 AM on December 31, 2014

Whoa, perfect. I only learnt to drive this year and have been driving for 6 months and often wonder how the car actually works, so these are fantastic, thanks.
posted by marienbad at 4:33 AM on December 31, 2014

And so I go to email this to someone and find he has emailed me this awesome looking motorbike!
posted by marienbad at 4:40 AM on December 31, 2014

I, too, have just learned to drive this year, and have spent the past six months learning how to drive without gritting my teeth, hyperventilating, or having an extremely weird person telling me what to do. It's mostly been ok. I'm quite torn on learning the internals though; is this stuff that is actually useful, or will I just end up disappearing down some kind of car-person rabbit hole?

On the other hand, those animations are amazingly cool! Thanks, Harald74!
posted by The River Ivel at 4:48 AM on December 31, 2014

I hope I never see another spring as long as I live!
posted by mccarty.tim at 4:48 AM on December 31, 2014

Dude, I have a Prius. I have not one clue as to what's going on under the hood.

I understand under the hood of a Prius is just two hot dogs in an old sweater.
posted by happyroach at 5:10 AM on December 31, 2014 [12 favorites]

or will I just end up disappearing down some kind of car-person rabbit hole?

A horrible fate, indeed.
posted by indubitable at 5:12 AM on December 31, 2014

And so I go to email this to someone and find he has emailed me this awesome looking motorbike!

Interesting choice of engine for such a futuristic looking bike.
posted by TedW at 5:19 AM on December 31, 2014

I'm quite torn on learning the internals though; is this stuff that is actually useful, or will I just end up disappearing down some kind of car-person rabbit hole?

Mechanics can be pretty shady, and even knowledgeable people can get burned. Eventually, your car will require some repair and maintenance, and knowing how it works, even roughly, can help you navigate that.

For instance, I had a highschool teacher who was charged (a lot) for a set of sparkplugs and wires as part of her routine 30k mile tune-up. Thing was, she had a diesel car, which doesn't use sparkplugs or have an equivalent that needed to be replaced on the same schedule. Understanding how her car worked would have saved her from being ripped off.

Conversely, I knew someone in college who just couldn't understand why the car wasn't stopping like it used to. He didn't know how the brakes worked, so he didn't know the pads need to be replaced at intervals - I showed him how to replace them and the rotors he wrecked by not replacing the pads (super easy, even for newbies) and the car was stopping like new.

Knowing how your car works makes you a safer driver and a shrewd customer.
posted by Slap*Happy at 5:32 AM on December 31, 2014 [6 favorites]

That differential explanation video gives me that top-of-the-head tingle every single time I watch it.
posted by sidereal at 5:36 AM on December 31, 2014

Here is a real test, on a full-size scale
posted by flabdablet at 6:10 AM on December 31, 2014

Often seen on hackaday.com via their retrotachular tag. You should go there.
posted by clvrmnky at 6:10 AM on December 31, 2014 [2 favorites]

Dude, I have a Prius.

Whisper-quiet!
posted by flabdablet at 6:11 AM on December 31, 2014

If I need to know anything about cars, I usually just wait for Brockles to join the thread.
posted by notyou at 6:30 AM on December 31, 2014 [1 favorite]

Surely you mean: Whisper-quiet?
posted by indubitable at 6:33 AM on December 31, 2014

Dude, a Prius has everything on that list.

Kinda interesting to watch cars in the process of shedding those subsystems, though. I wouldn't be shocked to find that whatever I replace the 2010 Mazda with doesn't have a (meaningful) transmission or differential.
posted by ROU_Xenophobe at 6:35 AM on December 31, 2014

Kinda interesting to watch cars in the process of shedding those subsystems

Yea, or the versioning of the same. Steel cable brakes, touted in said video, are now hydraulic (hence brake fluid). The legacy stuff is fun, but that may be because I own an older VW Beetle. From readings about them I've heard the pre-hydraulic braking ones (from the 40's or so I think) are altogether different monsters in that regard, and not in good ways. That and I've never understood why drum brakes seem to be more common, earlier, and still around more (or not?) than disc brakes, which seem to me as much the simpler arrangement. Cue Brockles perhaps...

I love videos like this and think oldschool engineers (and even videographers, some of that stuff looks downright CGI-ish in the gear video) were pretty damn amazing.
posted by RolandOfEld at 6:44 AM on December 31, 2014

I'm looking forward to the day when advances in materials engineering give us a pancake motor + wheel assembly with acceptable performance so driveshafts can just go away. That, plus permanent magnets instead of springs and active shock absorbers that return energy to the battery pack.
posted by flabdablet at 6:48 AM on December 31, 2014

That scuba/diving suit portion of the engine/fuel/air mix video... I'm still watching it but damn, can we get a video about that activity that's in this style. Wow. Epic and terrifying.
posted by RolandOfEld at 6:48 AM on December 31, 2014

I wouldn't be shocked to find that whatever I replace the 2010 Mazda with doesn't have a (meaningful) transmission or differential.

Really? I would. Even the Tesla Model S has a differential (or two).
posted by indubitable at 6:48 AM on December 31, 2014

I've never understood why drum brakes seem to be more common

Drum brakes allow more surface area for the brake pads. As we know from our physics class surface area doesn't affect braking power, but it does affect the amount of heat that gets dumped into each square inch of the pads, so larger pads can be made of less sophisticated materials and will last longer.l
posted by localroger at 6:59 AM on December 31, 2014

Really? I would. Even the Tesla Model S has a differential (or two).

Sure, but an AWD electric(-drive) car might just have four electric motors attached to the wheels, like flabdablet describes. Or it might have two motors and differentials like a Tesla D. Or just one fuck-you big motor and like differentials everywhere, man.
posted by ROU_Xenophobe at 7:03 AM on December 31, 2014

Metafilter: one fuck-you big motor and like differentials everywhere, man
posted by localroger at 7:07 AM on December 31, 2014 [3 favorites]

some of that stuff looks downright CGI-ish in the gear video

Before computers took their jobs, there were a class of workers called "draftsmen" who were not themselves engineers, but who were trained to make highly accurate engineering drawings. Those animations are what happens when you take a draftsman (or possibly a room full of them) and ask them to make an animation.
posted by localroger at 7:11 AM on December 31, 2014 [5 favorites]

The best way for the layman to learn auto mechanics is to buy a really old car: You learn what each subsystem does when you try to drive with a broken one, and the replacement cost teaches you how important it is.
posted by Dr Dracator at 7:18 AM on December 31, 2014 [6 favorites]

As we know from our physics class surface area doesn't affect braking power, but it does affect the amount of heat that gets dumped into each square inch of the pads, so larger pads can be made of less sophisticated materials and will last longer.l

Right and totally valid, but the actual mechanics of said device (drum vs disc) are what confuse me. You could, in theory, have a disc brake with pads as big as the disc itself and, again theoretically, negate the surface area issue and physics concern.

I guess what I'm saying is that putting brake pads on the outside of a disc spinning on the axle seems easier/simpler than putting pads inside a drum that operates with the axle. Or something. I'm sure I'm not considering all the facts and history but the mechanism just seems overly complex compared to the disc systems and I don't know why ye 'old wise engineers would have made that the case without reason, which I'm sure they had, so what is it!?! I must know...

localroger: yea, draftsmen were cool peeps, my boss while I was interning at the paper mill was actually a draftsman at said mill, lost his job when that computer revolution came through, went back and got his engineering degree and returned to the same mill. Pretty epic story and dude.
posted by RolandOfEld at 7:27 AM on December 31, 2014

You learn what each subsystem does when you try to drive with a broken one, and the replacement cost teaches you how important it is.

Quoted for truth.

Wait, why am I losing power and why does the engine sound like hell.

*consults internets, borrows gauge, does test*

Oh, no compression on number 4 cylinder. That's. not. good.
posted by RolandOfEld at 7:29 AM on December 31, 2014

larger pads can be made of less sophisticated materials and will last longer.

It's cheaper to manufacture, basically. You used to see a lot of cars with disc brakes on the front where the car needs more braking force and less fade (since braking shifts the car's weight forward) and drums on the back to save money where less braking force was needed.

Disc brakes, on all four wheels, started to become a selling point on some models and the feature trickled it's way down.
posted by VTX at 7:42 AM on December 31, 2014 [1 favorite]

Drum brakes are cheaper because casting is expensive. Brake drums are cast, and that's it; all the other parts are sheet metal. With disc brakes you need to cast a rotor and the caliper, and both parts are kind of complicated.

When you didn't have power brakes, and especially when you had cable brakes, drums had lower force requirements to apply them because of a self-energizing effect (as the shoe pivots into the drum). Parking brakes are still usually drum brakes for this reason.
posted by Huffy Puffy at 8:15 AM on December 31, 2014

Dude, a Prius has everything on that list.

Indeed, and if you understand how a differential works, you're halfway to understanding how the Hybrid Synergy Drive works, too. There's a planetary differential buried in there, in between the engine, driveshaft, and one of the electric motors.
posted by FishBike at 8:31 AM on December 31, 2014

I have had old VW bugs and a bus, a rabbit or two, and I did the vast majority of work myself including rebuilding bug engines, brake jobs, replacing front ends, etc. I now have a 2003 Jetta. I open up the hood and look in and then sadly shake my head and close the hood. All those things I used to fiddle with have either disappeared, require specialized tools, or some goddamn computer analysis machine to decipher error codes. Hence, I no longer do anything other than replace bulbs, batteries, and gas. And you know, I don't miss working on my car.
posted by njohnson23 at 10:29 AM on December 31, 2014 [2 favorites]

Dude, a Prius has everything on that list.

Well, not the (conventional) transmission or the hydraulic steering. Even non-hybrid modern cars mostly eschew hydraulic steering.

There's a simulator for Toyota's hybrid transmission system here.
posted by Western Infidels at 11:26 AM on December 31, 2014

The computer diagnostics actually makes stuff easier for the home mechanic, IMHO. With a cheap USB adapter and some software you can get the car to tell you what's wrong. So the car itself will tell you i.e. that the lambda sensor is not reporting correct values, so you check the wiring and/or replace the sensor. Especially for intermittent faults this is pure gold.

If it robs you of the joy of working on the car, though, I can sympathise. But I think a modern car is actually easier to work on in most respects than many 80s/90s models with a mess of valves, solenoids and vacuum lines that conspire to both keep the emissions down and put grey hairs in the head of the home mechanic.
posted by Harald74 at 11:29 AM on December 31, 2014 [1 favorite]

Surely you mean: Whisper-quiet?

Whisper-quiet indeed.
posted by Aizkolari at 12:10 PM on December 31, 2014

And you know, I don't miss working on my car.

Yeah then you won't miss the Service Manuals that most car companies don't make available to the public anymore.
posted by artdrectr at 8:38 PM on December 31, 2014

My favorite part of the video is the smartly dressed lady in hat & gloves driving standard. Like no big deal.
posted by St. Peepsburg at 7:43 AM on January 1, 2015

the smartly dressed lady in hat & gloves driving standard. Like no big deal.

And why shouldn't she be able to drive standard in an era when automatic transmissions hadn't been invented yet? The idea that $GROUP have difficulty with $ACTIVITY is generally bullshit, often maintained by $GROUP themselves for social reasons. But humans are very adaptable, and when there is a powerful need to get from point A to point B, most of us are fully capable of mastering three on the tree and a clutch.
posted by localroger at 11:07 AM on January 1, 2015 [1 favorite]

My favorite part of the video is the smartly dressed lady in hat & gloves driving standard. Like no big deal.
Er. The vast majority of the rest of the world outside of the US (ladies included) are able to drive manual cars with no issues.

Here's a rather nattily dressed older lady you may have heard of driving around no problem in a manual car.

Drum brakes are cheaper because casting is expensive. Brake drums are cast, and that's it; all the other parts are sheet metal.

Well. The hydraulic actuator for the shoes in a drum brake system is also cast, but that's possibly being pedantic... Casting has actually become a LOT cheaper, although that does support your argument, but not not the way you perhaps expected. As castings became cheaper, it was harder to justify the small difference in cost to put drums on when they're absolutely terrible and much, much less efficient. They also have a lot more servicing requirements compared to discs.

Also, as cars became faster and more powerful, drums just weren't able to do the job. They're terribly by comparison in all respects.
posted by Brockles at 11:30 AM on January 14, 2015