Can someone please explain how the clutch and gears work in a car as I’m learning and I can’t quite understand it
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Linked to a video under tohowie’s comment, but if you want a verbal explanation, here goes:
There are two important types of velocity for gears, rotational and linear. Rotational is how many times something spins in an amount of time, linear is how much distance it covers.
If I walk around a room once in a minute and the Flash runs around the whole city in a minute, we both have the same rotational velocity (we each did one rotation!), but he’s obviously covering more distance than me.
Ultimately what we want to do is take rotational velocity in our engine (measured as RPMs) and get linear velocity out of our wheels. But for our wheels to turn, we need to push the whole car which is really, really heavy.
So what do we do? We help our engine by letting it “spread out” the push over many rotations. By using differently sized gears, we can let the engine turn many times for each turn of the wheel. If our engine gear is half the size of the gear going to wheel, then each turn of our engine only has to drive half a turn of the wheel. By altering the ratio of those gears, we can alter how hard our engine has to push.
In low gear (the engine gear is small relative to the wheel gear), your engine can turn more times to push the wheel, which takes strain off the transmission. In high gear, you can get more power out of your engine.
Your car can have several sets of gears, and the clutch temporarily separate the gears so that you can move from one set to another.
I’m trying to practice explaining things to my daughter, watch some automechanic is going to see this and cry.
If we built a car with the engine directly connected to the wheels, we’d have problems, since for the engine to spin, the wheels would also have to. So if you stopped your car, the engine would stop spinning and die. The solution to that (in a manual transmission) is to have a break between the engine and wheels, and put a clutch in that break to let you disengage the engine.
The oversimplified version of how a clutch works: There’s basically a disc attached to the output shaft of the engine, and another disc attached to the input shaft of the transmission. Under normal operation, these two discs are pushed together hard enough that they don’t slip against each other, making it behave as though the whole thing was a single drive shaft. When you push the clutch pedal in the car, these discs are pushed away from each other. Push the pedal a little and they’ll rub together, transferring only a little of the engine’s power into the transmission. Push the pedal far enough and the discs stop touch properly, completely disconnecting the engine from the transmission.
The transmission is simply a set of different sized gears on two different shafts. Shifting changes which gears are connected to each other, which changes the mechanical advantage of the engine to the wheels. Mechanical advantage explained: systems like gears, levers, pulleys etc. exchange force for distance. You feel this on a bike. In high gear you don’t have to pedal as fast as a low gear, but you have to push harder. A car transmission does the exact same thing.
If you want to understand the specific workings of a manual transmission, you’re better served by seeing pictures or animations of how the parts interact than reading a description. [This video has a decent animation](https://www.youtube.com/watch?v=devo3kdSPQY), or you could look for gifs in Google or whatever.
They are much most complicated but envision them as [different sizes, like THIS](https://www.vernier.com/files/manuals/kw-bwx/Content/Resources/Images/KidWind/KW_gear_ratios_BW_250x160.png).
*Imagine while you are driving, that whatever gear you’re in is the only one engaged and spinning. It’s in control and the engines job is to make it spin .*
In gear one (1), the smallest gear, you have the most acceleration because it’s so tiny and easy to spin, but lowest top speed, because it takes a bazillion and a half REVOLUTIONS to make it even a small distance. In fact, trying to make it spin to that fast with a machine would not even be practical.
So, in order to give us a little more SPEED thus making us move faster, we want a gear that can go a little bit more with a little bigger turning radius for the speed we are currently moving.
So, we press the clutch, which, sort of unlocks, and unwinds all the levers and chains and gears, and then we move the stick to second gear (2). Then, when letting go of the clutch it locks everything back into place, now surrounding one step up higher than we were before and the car “breathes a little easier” because it’s not trying to spin a matchbox tire sized wheel down a freeway.
Now we are in second gear. A little more speed, a little less acceleration. It basically happens again at some point because gear two is only slightly bigger than one.
*Speed up, we want to go faster. *CLUTCH* *SHIFT**
Third gear. A little more speed, a little less acceleration.
*Speed up, we want to go faster.*
Fourth gear. A little more speed, a little less acceleration. Our acceleration is so bad now because our gear has gotten a lot bigger than first gear. Now, it would be entirely impractical to try to accelerate a car from zero at this point because it’s just so bad.
Top speed. Fifth gear.
Biggest gear with the biggest radius. All we have to do it make it spin a few times a minute because the its just so big it can travel a mile while only spinning a few times. It’s easy to the engine to keep this speed, too, because since its a big gear with a big radius, we have so much momentum.
We’re cruising.
(The very simplified way my driving instructor taught me)
Imagine your clutch pedal opens 2 plates that usually sit closed on one another. When you put the car in gear, you open the plates (pressing the pedal), slot the gear in that gap (putting the car into 1st), and close the plates (releasing the pedal). The gear is spinning fast, so when the plates close they have to “catch” the gear to spin with them. When they do catch, thats your biting point and off you go. When they dont catch, the gear slips and you stall…
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