The airbrake-equipped apparatus should bleed to a significant level in order for the vehicle to operate within blank seconds of starting.

• A. 30
• B. 60
• C. 90
• D. 120

Answer: (B)

Air brake systems require time to build up usable pressure after the engine starts. The compressor fills the reservoirs, the governor controls cut-in and cut-out, and the parking brake and other brake-application functions rely on sufficient air pressure before you can safely move the apparatus. Reaching a significant level of system pressure within about one minute ensures the brakes will release and the vehicle can operate (move and respond to brake controls) promptly after starting. If the pressure takes longer to reach that level, you could be moving with inadequate braking or control. The 60-second target is the standard balance between rapid readiness and reliable pressurization. The other timeframes would either rush a still-low-pressure system or unnecessarily delay operation.