What does the trolley do in hoisting systems?

The role of the trolley in hoisting systems is essentially to move along the bridge rails. This movement allows the trolley to position the hoisted load over the desired location effectively. The trolley is typically equipped with a hook or another attachment mechanism that connects to the load, enabling it to be lifted or lowered as needed. By traveling along the bridge rails, the trolley facilitates horizontal movement of the load within the area defined by the bridge, which is mounted overhead.

In comparison, other options present functions that are either performed by different components of the hoisting system or are not specific to the trolley's primary purpose. For example, supporting the load directly is primarily the function of the hoist itself or the hooks used in conjunction with the trolley. Similarly, while the hoist is responsible for raising and lowering the load, the trolley's function is not to lift but to traverse. Finally, securing the load during lifting is also not a direct function of the trolley; rather, that is typically the role of the hoist or the securing mechanism used for the load.