What prevents the two stages of the primary servos from being turned off simultaneously?

• A. Electrical interlock
• B. Hydraulic interlock
• C. Mechanical interlock
• D. Electrical circuit

Answer: (C)

A mechanical interlock is a physical linkage that ties the two stages together so they cannot be deactivated at the same moment. This ensures that when you command one stage to shut off, the other remains energized, preserving hydraulic servo action and keeping control authority available. It provides safe sequencing and prevents a total, instantaneous loss of servo power, which could complicate handling. Electrical interlocks or hydraulic interlocks rely on separate circuits or pressure states, but the design in this case uses a mechanical linkage to guarantee the staged shutdown behavior.