Which of the following is NOT a pneumatic component of the TU1?

The brake pedal actuator is the correct response because it is not typically categorized as a pneumatic component within the context of the TU1 system. Pneumatic components are usually defined as parts that utilize compressed air to function, such as valves and switches designed for controlling air pressure and flow.

The relay valve, pressure switch, and magnet valve all play crucial roles in managing and regulating pneumatic systems. The relay valve serves to control air flow and pressure, the pressure switch monitors air pressure levels to trigger other components when certain thresholds are met, and the magnet valve operates based on electric signals to control the passage of air.

On the other hand, the brake pedal actuator is primarily associated with mechanical or hydraulic systems for brake operation and does not function within the pneumatic framework established by the other components listed. This distinction highlights the non-pneumatic nature of the actuator as part of the system, thereby identifying it as the correct choice in the context of the question.