What does the parking brake on a forklift prevent when engaged?

The parking brake on a forklift is designed primarily to prevent unintentional movement when the forklift is not in operation. When the parking brake is engaged, it secures the forklift in place, ensuring that it does not roll or shift due to gravity or inadvertent actions by operators. This feature is particularly critical when the forklift is parked on an incline or after it has been unloaded, preventing accidents or injuries that could occur from unanticipated movement.

The other options relate to different aspects of forklift operation. While overloading the tires could cause issues, it is not the direct function of the parking brake. Similarly, the wearing down of brakes is a result of usage rather than the engagement of a parking brake, and the improper lowering of forks does not directly link to the parking brake's function. Therefore, the primary and essential role of the parking brake is to ensure stability and safety by preventing any unintended movement of the forklift when it is parked.