How come we can’t just add X amount of gears to a transmission and have one of the most efficient cars ever?

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How come we can’t just add X amount of gears to a transmission and have one of the most efficient cars ever?

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Anonymous 0 Comments

My bike has 21 gears but it is very rare to have any use for more than about 7. People pay $1000 to shave a pound off the weight of their bike, then add nearly useless gears and destroy the efficiency they paid $1000 for.

Anonymous 0 Comments

More gears more weight plus cost. CVT’s on the other hand can be more efficient but can only handle a relative low amount of power. For automatics we’re still trying to find the perfect amount of gears. We’ve found that for manual 6 seems to be the best for efficiency and power.

Anonymous 0 Comments

In short because there is a point of diminishing return. Also the law of conservation of energy plays a factor here i.e more gears means more friction, heat, wear etc.

Anonymous 0 Comments

That’s exactly what we did! In 1950 Chevy came out with the first automatic transmission, the power glide! It had 2 gears and that was it, low and high. It wasn’t very efficient but it was ground breaking as a car could finally shift itself.

Then in 1969 Chevy came out with the Turbo 350 transmission. It had 3 gears closing the gap between low and high. It made the cars more fuel efficient and improved performance. In fact Turbo 350’s and Turbo 400’s (a beefier version of the 350) are still used for drag racing. They are the best transmissions for holding BIG power when upgrades. A fully upgraded Turbo 400 can handle 4,000+ horsepower. Crazy for something designed in 1969.

After that we get the 700r4. It was still an old school transmission but they added a 4th gear. This is an overdrive gear which is great for fuel mileage. It’s not designed for you to accelerate in, just drop the RPMS for better mileage. So once you hit 70mph and stopped accelerating and began to cruise, it would shift into 4th to get better mileage. This transmission gave way to the 4L60E & the 4L80E. The 4L60E is a 4 speed like the 700r4 except it’s electronically controlled. The 4L80E is just a beefier 4L60E like the turbo 400 is a beefier turbo 350.

In the ever increasing battle for better mileage in 2005 Chevy came out with the 6L80E. This is similar to the 4L80E but it has 6 gears instead of 4. Then in 2017 GM stepped it up again and made the 10L80E. A 10 speed transmission designed for high end sports cars.

Now it’s important to note WHY having more gears increases efficiency and why adding more gears isn’t always the right answer. The more gears you add, you suffer from diminishing returns in the area of efficiency. It also makes the transmissions significantly more expensive and complex. To be truthful the 10 speed is probably the most gears they will ever do and even then it’s a bit of a gimmick.

Ignoring the engine on the planet is going to have a spot in the RPM range where it is operating at its highest level of efficiency. It’s going to be fairly narrow just a few hundred RPMS.

So to get more efficient cars we want to keep them in that range while accelerating and cruising. By adding more gears you can maximize the amount of time you spend in that RPM range. If you have a 3 speed your range of RPMS range while accelerating may be from 1,500 to 3,500 RPMS. That’s a 2,000 RPM range, much larger than the efficiency range of the engine. If you have a 10 speed you may be able to keep the RPM range between 2,000 and 2,500 RPMS, a 500 RPM difference and definitely keeping you in the engines efficiency range. As you add more gears that range gets smaller and smaller. It doesn’t really improve efficiency because it’s still sitting in the efficiency range of the engine either way.

To get more efficiency you have to look at other ways. Things like better aerodynamics, less weight, and less friction.

Anonymous 0 Comments

That’s exactly how it is. Modern cars have automatic transmissions with more than regular 5 or 6 gears as common for manual transmission. The thing is it’s applied to automatic ones because it’d be horrible to manually switch 8-9 gears. But semi-truck (or whatever it’s called in English) drivers have way more, I believe up to 18 or something.

Btw, combustion engine cars are inefficient because of their engines which are inefficient by design. Diesel could theoretically be ~55-60% efficient, gasoline engine is even worse ~40%. That’s why electric engine with efficiency up to 99% is hella better option.

Anonymous 0 Comments

You need more power to be able to drive a higher gear. An example is my bike. I fitted a new final drive with a longer ratio because my old one grenaded itself. Now for a given speed I have a lower RPM in fifth gear but the ratio is too tall for my bike’s engine to overcome and I have a higher top speed in fourth.

So now I HAVE to fit a big bore kit to get more power.

Anonymous 0 Comments

Its common for trucks or busses to have 10-12 gears, some even 18 gears. But thats because they have to pull tens of tons, with relatively small engines. For example a 20t iveco truck has a measly ~ 300 hp engine, with a 9 manual or 12 semi auto gearbox.

Anonymous 0 Comments

Gears don’t increase the power of the car. To drive at a given speed you need a given power, the engine has to provide that power no matter what gear you are in. In fact, with a transmission it has to provide a bit more power because of friction in the transmission.

Combustion engines are inefficient when they run very slow (few, slow combustion cycles) and when they run very fast (large losses from all the moving parts). They have a range where their efficiency is the best. Gears are used to keep the engine closer to that range for a large range of car speeds. With something like 5 gears you are already close to the maximum across the whole relevant speed range. Going to 10 gears is a very small improvement, going to 20 would be an even smaller improvement.

Anonymous 0 Comments

They did make one car..but the inventor misteriously disappeared, his patent missing and family went silent.

Big corporation don’t want u to have one efficient car…that will last years..decades…they want u to buy one every year …

Anonymous 0 Comments

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