You park a trailer with compressed air-braking system for a short period. How can you disengage the service brake of the trailer?

You answered correctly. For trailers with a compressed air-braking system, you can disengage the service brake by activating the release valve. This releases the pressure that is keeping the service brake engaged. Simply venting the brake line or releasing the parking brake will not have the intended effect for the service brake in such systems. Knowing how to properly disengage the brakes is important to prevent unintentional movement or brake damage. If you face similar questions, remember that the service brake can be specifically released with the release valve on compressed air systems.