If counter weights on tall cranes are used for stability, why don’t the crane lean backwards without any load ?
In: Physics
Some cranes can adjust the position of the weights as they move the load around. Weight farther away from the pivot point have a greater effect: the crane will move weights towards or away from the center as needed to maintain balance.
But mostly, the cranes are just built with enough strength to hold up against the counterweights. That also means they’re strong enough to hold up against an unbalanced weight of the load…just not as unbalanced as it would be without the counterweights.
Like, imagine the crane can withstand 1000 pounds of unbalanced weight in any direction. If the crane has 500 pounds of counterweight, then without a load it’s going to “lean” 500 pounds backwards, but that’s within its tolerance. With that counterweight, it can hold a 1000 pound load easily without worrying about becoming unbalanced – the 500 pound weight pulls one way and the 1000 pound load pulls the other, so they cancel each other to 500 pounds in the direction of the load, which is *far* below the point when it would unbalance. Without the counterbalance, the load would be pulling with the full 1000 pounds and it would be really close to unbalancing.
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