Crowbars are commonly used to open nailed wooden crates or pry apart boards.

How does a crowbar make work easier?

The crowbar is a classic example of how the lever is employed to do work easier. With the crowbar, carpenters can easily extract nails from wood that would be nearly impossible and extremely inefficient without such a handy machine.

Do crowbars break?

One needs to realize that they are not indestructible and they do have limits. Generally, the cheaper ones are case hardened and will snap transverse to the direction of pressure and the fracture will be like a knife slice through the shank.