Question- how to actuate something when power is lost/turned off

I am looking to add a (simple and low cost) mechanism to a linear actuator such that when power is cut, a brake/locking mechanism of some variety is applied. The axis is affected by gravity, and may be carrying some weight. If the system loses power, or when it is in a low power mode (i.e. no holding torque applied), I would like to prevent the axis from moving from gravity.

My initial thoughts are to have a ratchet mechanism, with the pawl/pin held in place such that downwards movement is prevented, and then, when the system has power, use a spring-loaded solenoid to push the pawl out, and allow the ratchet to free-wheel.

The problem is that the solenoid draws a significant amount of power, and would need to be in an actuated state for long periods of time whilst the axis is moving.

Are there any alternatives for something that triggers when a system loses power, but that uses less power in the “awaiting trigger” state?

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Thanks

submitted by /u/newoodworker
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