Manufacturing Skill Standards Council (MSSC) Safety Assessment Practice Test

Which type of interlock physically stops a machine's operation when the guard is removed?

1. Hydraulic

2. Electrical

3. Mechanical

4. Pneumatic

The correct answer is: Mechanical

The answer is mechanical interlock because it is specifically designed to provide a physical barrier that prevents a machine from operating when the guard is removed. Mechanical interlocks utilize physical components that lock into place when the guard is closed, ensuring that as soon as the guard is taken off or opened, the machine cannot be activated. This type of safety measure is essential in preventing accidents or injuries caused by unguarded machinery. In contrast, other types of interlocks, such as hydraulic, electrical, or pneumatic, might involve systems that use fluids, electrical signals, or air pressure to control machine operation, but they do not create a direct physical barrier like a mechanical interlock does. Therefore, while they may provide safety functions, they do not stop the machine's operation in the same straightforward manner that a mechanical interlock ensures.