What would be an appropriate sensor to determine if a hydraulic system is functioning properly at its end limits?

A contact limit switch is an appropriate sensor for determining if a hydraulic system is functioning properly at its end limits because it is specifically designed to detect the position of moving parts within the system. These switches can provide reliable information by physically making or breaking a contact when an actuator or other element reaches a predefined position. This is crucial in hydraulic systems, where precise control and monitoring of actuator movement is necessary, especially at the endpoints of operation.

By using contact limit switches, operators can verify that a hydraulic cylinder or other actuator has reached its specified limit, ensuring that the system remains safe and operates within its designed parameters. In doing so, the limit switch can prevent potential mechanical overloads and other hazards associated with unintended movement beyond these limits.

Other options like a tachometer, linear transducer, or pressure switch serve different functions. A tachometer primarily measures rotational speed, a linear transducer provides position feedback through measurement but may not give specific endpoints, and a pressure switch monitors system pressure rather than mechanical position. Therefore, for end-limit detection, a contact limit switch is the most suitable choice.