Gearing Ratios?

LCKKN]HT · #1 11-16-2002, 02:49 PM

I just got my 3.0 motor and gears for my Z-car. This has shaved 1 second off of my 0-10' time. However, I don't understand the gearing aspect. The pinion gear that came with the 3.0 motor is slightly larger than the pinion gear on my 2.2 motor. The idler gear is a bit smaller than the gear on my 2.2 motor. What does this actually do?

SuperShot · #2 11-16-2002, 04:06 PM

Well, think about it...
What would happen if you put bigger wheels on your car?
Well, if the wheels are turning at the same rate, your car would be faster since it goes further for each revolution of the wheel.

The same goes for the gears. If you have a big gear on the motor, it will give you more speed. And if the big gear is driving a small gear, the small gear will do more revolutions for each time the big gear goes around. Think of a bicycle. The top speed is acheived with a large gear in front (pinion) and a small one in the back (idler).

Furthermore, to get everything to fit snugly in a bit where you can't adjust the position of the gears, you will need to reduce the size of the idler to compensate when you get a bigger pinion. In effect, you increase the speed in both places at once.

The second point to consider is that a motor generally has lower torque if it has a higher top speed. This is part of the physics of electrical motors. You can make a motor that outputs both more torque and speed, but it would need more electricity to do this.

So if you have a faster motor, and a larger pinion, you will get very little torque overall. This is why people advise you to lower your gear ratio when you get a faster motor.

By the way:
Has someone measured battery life with different motors? It would be fun to see a comparison. Also: Has someone ever tried to disassemble for instance a 3.8 and a 1.0. It would be fun to have a look at the difference in the innards. (I don't have any bust motors to open, yet)

LCKKN]HT · #3 11-16-2002, 10:37 PM

I haven't timed it but I noticed a difference between my 2.2 and my 3.0 motor as the latter having a shorter run time. However, I have a Z-Car (clone).