What is the role of hydraulic interlocks on aerial devices?

• A. They prevent unintended movement and raise/lower operations unless safety conditions (e.g., platform properly seated, outriggers deployed) are met.
• B. They control the device's ground speed and steering.
• C. They store hydraulic fluid for emergencies.
• D. They provide warning signals when units are near power lines.

Answer: (A)

Hydraulic interlocks are safety checks built into the aerial device’s hydraulic system. They prevent raising or lowering the platform and any movement of the boom unless the safe conditions are met—typically the platform is properly seated and the outriggers are deployed and stable. This ensures the machine is on a solid base and cannot operate if it could tip or become unstable.

Other functions described don’t fit this role. Ground speed and steering are handled by the drive system, not hydraulic interlocks. Storing hydraulic fluid is the job of the reservoir, not the interlock system. And warning signals for proximity to power lines come from separate safety systems, not hydraulic interlocks.