What is the first step when working with service brakes on air brake systems?

Caging the spring brake is indeed a crucial first step when working with service brakes on air brake systems, especially for safety reasons. Spring brakes act as a fail-safe, engaging when there is a loss of air pressure in the system. By caging the spring brake, you ensure that the brakes can’t inadvertently engage while you're working on the service brakes, allowing for safe and effective repairs or inspections. This step mitigates the risk of injury or unintended vehicle movement that could occur if the spring brakes engage unexpectedly.

Testing brake pressure, inspecting brake pads, and checking for air leaks are all important tasks, but they typically follow the initial safety measures—like caging the spring brake. Once the spring brake is secured, you can more confidently proceed with these subsequent checks and repairs.