2210 - Without a cable, it could be a shifting weight for a seesaw system weighing several tons ? perhaps a ramp.
Suppose it takes 50 foot-tons to lift the ramp and when the ramp is down, the fixed counterweight supplies 45. If the rolling weight is 2 feet from the pivot, it will supply 1.5 foot-tons, so 3.5 foot-tons (50
- 46.5) will hold the ramp securely down.
Suppose the rolling weight is on tracks that are inclined slightly toward the pivot. When you start to lift the ramp, the tracks tilt slightly away from the pivot. If the weight rolls 8 feet, it will be 10 feet from the pivot and supply 7.5 foot-tons, for a total of 52.5. Now
2.5 foot-tons will lift the ramp and hold it securely up.