As the title says, I know that different shifts mean different gear sizes bein used, but I don’t understand why it makes you unable to start moving the car. I have been able to start a couple of cars on the 2nd shift as an experiment and I understand that I could damage the car and I do it just once for testing purposes but I don’t understand why I cannot do so on other shifts. To clarify, I mean start as in start moving the car and not just turning the car on. Thanks
In: Engineering
Sure you can, if you want to do a lot of damage to your clutch. (my old 2006 impreza 2.5i had an issue a couple of times where a linkage in the shifter would … disappear or whatever, and i’d be stuck in whatever gear i was in. both times it was 3rd gear. I managed to hobble it to a garage both times it happened.)
You can, you just need to slip the clutch more so the engine doesn’t stall as the car gains speed. If you do it a lot you’ll wear the clutch out quickly while driving slowly.
You can absolutely do this with older cars
I drove several where it didn’t make any difference whether you started moving in the first or fourth gear 😅 (Not my cars tho)
Manual cars can start on higher gears, it’s just not very efficient nor good for your car. It takes a good mastery of your clutch but I can start my Mazda 3 on 6th gear, it just takes forever. I did it several times to show people I was teaching to drive that they were too rough with their clutch.
Gears are just the wheel equivalent of a lever. Like, pulling a nail for example – you could never do this with your fingers because you’re not strong enough, but the claw of the hammer allows you to multiply your strength with leverage, gears do the same thing.
Lower gears have more leverage for getting the car going, but are limited by a slow top speed. Once you get rolling, you can shift into higher gears to lose leverage but gain speed.
Many trucks, especially big ones like dump trucks and 18-wheelers, only have those low gears to help them get moving when loaded. If the dump truck is empty, or no trailer attached, you can start them in a much higher gear because the extra leverage is not needed when they’re not fully loaded.
Some cars do. For example, I have a manual pickup which has a very low 1st gear designed to get heavy trailers moving. Normally, you would just start in second.
Basically it all depends how your vehicle is geared. Gears are one way to give you mechanical advantage. Basically, you can trade speed for power and vice versa. When you need lots of power, you pick a slow gear. When you need to go fast, you pick a higher gear.
It takes a lot of power to get a vehicle up to speed, but much less power to keep it at speed. Hence, starting in a low gear and working up to a high gear.
You could just put a massive engine in your car that has enough power to do everything (like an EV), but for a gas car, that would be really heavy and waste a lot of fuel.
Did you ever try to ride a bicycle starting with the highest gear? You probably can’t even get it rolling! Same principle!
In short, mechanical advantage. Think of the gears of a transmission in a vehicle as kind of like a bicycle with multiple gears. When you’re in a very low gear on a bicycle, with the rear on the biggest sprocket and the front on the smallest sprocket, it’s very easy to push the pedals no matter whether you’re going up a hill or starting from a stop. You do have the issue of only being able to pedal your legs so fast, and it’s really easy to get your legs going as fast as you can comfortably pedal but the bike isn’t moving very fast because it takes a lot of turns off the pedal crank to equal one turn of the rear wheel. At the other end, if you’re in a very high gear, like when the rear is on the smallest sprocket and the front is on the largest, you can pedal fewer revolutions to make one revolution of the rear wheel, but it’s much more difficult to press those pedals and if you’re going uphill it may be so difficult you can’t continue in that gear. A car transmission works in the same principles, just with an engine turning a crankshaft instead of legs pushing a pedal what and all the gears are in one place (except for the final drive, but that doesn’t change in on-road passenger cars so we’re pretending it doesn’t exist for this example) instead of spread out. A lower gear allows the engine to more easily turn the wheels due to mechanical advantage but the tradeoff is that the engine will run out of usable rpm range before the vehicle is moving very fast, so then you can shift gears to provide a little less mechanical advantage but you get a higher top speed, and so on until you run out of either gears or the power to push the car any faster in the gear you’re in.
You can bump start then in any gear including reverse BTW, manuals of course. Just depends on how fast you want to push or tow them.
I got the shop truck to start in 5th gear way back in my first job. It wasnt pretty, but it went.
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