00:00How can a backpack-sized engine pull a truck weighing dozens of tons?
00:03The secret is hidden in the gears most people never notice.
00:07Every time one gear transfers power to the next, the speed drops a little.
00:10Then another gear, and another.
00:12It looks like power is being lost, but the opposite is true.
00:15What disappears is speed, while torque keeps increasing through each gear stage.
00:19By the final gear, it may spin dozens of times slower,
00:22yet produce enough force to pull an entire truck.
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