Which term refers to a protective element in mechanical devices?

The term "Schutzkappe" refers specifically to a protective cap that is used in mechanical devices. This element serves as a safeguard, preventing damage or contamination to the components it covers. Schutzkappen are commonly used in various applications, such as protecting threaded parts, sensors, and other sensitive areas from debris, moisture, or accidental impacts. The application of this term aligns with its definition and use in mechanical contexts, making it the correct choice for identifying a protective element in mechanical devices.

The other options, while they may relate to protective or covering elements in broader contexts, do not specifically denote a protective element in the same way. For instance, a "canopy" typically refers to a covering structure or fabric over an area but is not specific to mechanical components. "Buchse" translates to "bushing," which is a mechanical component that provides support or reduces friction, and does not serve as a protective cover. "Kartusche" generally denotes a cartridge, often used in the context of storage or containment of materials, but doesn't pertain specifically to a protective element in mechanical devices. Therefore, the specificity of "Schutzkappe" as a protective cap makes it the most fitting term for this question.