Which action relates to making something tighter in a mechanical context?

In a mechanical context, making something tighter is directly associated with the action of "Anziehen." This term translates to "tighten" in English and specifically refers to the process of increasing the tension or applying a force that brings components closer together. This could involve tightening bolts, screws, or any fastening mechanism to ensure they maintain a strong connection and do not loosen during operation.

The other terms do not relate to the action of tightening in the same way. "Schwergängig" refers to something that is hard to move or operates with difficulty, which does not imply the action of tightening. "Drehmoment" translates to "torque," which is a measure of rotational force but not an action by itself. Lastly, "Entlüften" means to vent or release air, which pertains to reducing pressure rather than tightening. Thus, "Anziehen" is distinctly the appropriate term for making something tighter.