This boat winch uses a lever and a gear to enable one person to pull a heavy boat out of the water. Turning the long handle causes the little gear to drive the big one, which turns the drum that winds up the cable to the boat. It takes many turns of the little gear to cause the big gear to rotate once, and for each turn of the little gear the long handle goes around in a large circle. Comparing the large distance that the handle goes in making the drum turn once (and the amount of cable that gets wound in) tells us the ratio of the force that the hand exerts on the handle to the force that pulls in the boat: it is clearly a factor of 50 or more. If a force of 500 pounds is needed to pull in the boat, this device will make it child's play.

(The two gears at the back of this device are part of a rachet device, which locks the mechanism when you stop turning).
The unit on balanced forces