What is the main function of a constant-pressure switch in power tools?

A constant-pressure switch in power tools is primarily designed to ensure that the tool remains operational only as long as the switch is actively held down. This safety feature is crucial because it prevents accidental activation of the tool when not intentionally in use, reducing the risk of injury and enhancing control during operation. By requiring continuous pressure on the switch to maintain operation, it adds an element of safety, ensuring that the user cannot inadvertently cause the tool to run when they’re not in a steady, controlled position.

The other options do not accurately capture the primary role of the constant-pressure switch. Variable speed control pertains to a feature that allows the operator to adjust the tool's speed based on the pressure applied, while automatic shut-off mechanisms are related to safety features that engage when the tool is not in use, but they do not define the role of the constant-pressure switch. Additionally, storage functionality is not related to the operation of the switch but rather pertains to tool maintenance and organization.