From the previous page we have learned that we can work out the velocity ratio if we know how many teeth are on the cogs or, in the case of a pulley system, how big the wheels are.
Once we have the velocity ratio we can work out what speed is output provided we know the speed of the driver cog or wheel.
For instance, from our example, if we know that the driven cog is travelling 5 times slower than the cog that is driving and provided that we know how fast the driver is going we can work out the final speed of a pair of cogs or wheels.