I don’t quite understand the use of a gearbox. What is the purpose of it?
Say for example some machine use a gearbox for some reason is it possible to replace it with a motor and a speed contorller?
Thank You.
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A gearbox with multiple options to select allows you to change the relationship between engine speed and ground speed.
For combustion engines, this is really important as they can’t operate below a certain speed (stall) or above a max speed (red line aka the point where they might blow up). This range isn’t particularly large and to increase speed, you need to get more power which in these engines means increasing the engine speed and the engine doesn’t do that very well if the engine speed is too low compared to the power required which is why we use lower gears (higher ratios) to accelerate from a start or to pick up speed quickly.
Electric motors generally have a much wider speed range and most importantly, they can apply full power at zero speed. As a result, most electric vehicles have much fewer gears than ICE vehicles do.
For light vehicles and small to medium trucks, an ICE model generally has 5 or 6 gears, sometimes more in automatics. Heavy trucks often have 18 or more gears and a very narrow engine speed range (often just under 1000 to a red line at around 2000 rpm)
Electric light vehicles and even some smaller electric trucks like the Fuso E Canter only have a single forward gear and rely on controlling motor speed to accelerate. Very heavy electric trucks (e.g. Volvo FE electric and Scania electric) use a two speed gear box to allow the motor to run at lower rpm when the truck is going faster. I suspect that this is because the larger motors used for trucks of this size have a bit more drag when spinning at high speed so the extra power loss in the transmission is offset so it still works out more efficient
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