What is the function of the hoist limit switch in overhead cranes?

The function of the hoist limit switch in overhead cranes is to control the upper limit of the load block. This switch is a crucial safety feature designed to prevent the hook and load block from traveling too high, which could lead to accidents or damage to the crane and the load being handled. When the load block reaches a predetermined upper position, the limit switch activates and interrupts the hoisting motion. This ensures that the load does not exceed safe operational limits, protecting the crane's structure and the safety of personnel in the vicinity.

In contrast, other options refer to different functions that do not pertain specifically to the hoist limit switch. Operating controls relate to the driver’s ability to manipulate the crane, indicating load weight is a function of load cells or scales, and preventing excessive speed typically involves control mechanisms or features that manage the operational speed of the crane rather than an upper limit on load movement.