To Gear Or Not To Gear

Tyre SmokeI like cars. A lot. They move me, not just physically but also with a degree of emotion. Whilst I embrace the internal combustion engine and motorsport, I actually like the options that electric motors give and they can make cars better. However, I find myself getting frustrated with the exponents of this technology as they keep pushing views which I see as being rather peculiar.

My most hated view is that you don’t need a gearbox with an electric motor. Yes, this is true, however they ignore the fact that you don’t really need a gearbox with an IC engine. I’ve driven vehicles where you can put them in one gear and they will go from zero to their top speed without the need to use any other gear. There is footage on Youtube of a Corvette Z06 being taken from 0-120mph in 4th and even 0-160mph in 5th. Looking back at early automobiles there were quite a few which didn’t use a gearbox yet here we are with virtually all production vehicles fitted with gearboxes.

The point of a gearbox is threefold – firstly to make a car easier to drive, secondly to improve performance, and thirdly to improve economy. The first point isn’t really an issue as you can play with the control of an electric motor in order to make it happen, there are ways to make an IC engine flexible enough to do this as well. By combining a smaller than expected motor with a gearbox you get the same performance as you would for a larger motor whilst using less energy to achieve it. Before quoting efficiencies etc at me, people need to learn that yes, expressed as a percentage, using a gearbox is less efficient, but when expressed as a way to use a set amount of energy properly, the gearbox setup will win.

What are the downsides of a gearbox? A bit more complexity within a system and it will drain energy from whatever gets to the wheels. If I remember correctly, if used in a front wheel drive setup then power losses tend to mean you get 80% of produced power at the wheels. That’s a big number when you’re looking at the EV market considering you need to make the most of the limited power you have. The advantages of a gearbox? It allows you to run a much smaller motor whilst retaining the performance of a larger one, and with a smaller motor you get a saving in energy usage even with the losses from the gearbox. Next advantage comes the benefits to recharging because the gearbox would keep the motor rpm high as the vehicles slows. This should make it either as efficient as, or more efficient than, a motor only setup. When weighed up against the losses a gearbox system would incur, the benefits look like outweighing the losses.

So what does this mean? It means that we may soon see the rise of sequential transmissions with extremely fast shift patterns being implemented in EVs of almost all shapes and sizes. All of that comes from motorsport which goes to demonstrate that competition improves the breed. Oh, and it’s fun to watch, at least to me.


About Igor

Playing with technology and looking at making some monsters

Posted on May 18, 2012, in Transport and tagged , , , , , . Bookmark the permalink. Leave a comment.

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