The two linear actuators that I know, 61927c01 Linear Actuator and 92693c01 Linear Actuator Mini, have a built-in clutch (that makes a clicking sound when feeding the actuator torque when it's fully retracted or fully extended).

Linear actuator Linear actuator mini

What's inside the actuators? Is there a worm gear inside? How does the internal clutch work?

1 Answer 1


There is definitely a worm gear and a clutch inside, as reported by the (now defunct, but luckily archived*) TechnicBricks blog:

exploded view of a linear actuator

view of the surfaces between the orange and white parts

closeup view of the metallic worm gear on the end of the shaft

The orange part is the input and engages with its serrated surface the pins of the white cylinder. The flexibility of these pins allows the rotation of the input axle while the actuator shaft is blocked - providing the clutch functionality.

The inside of the white cylinder has grooves in it which then engage and drive the worm gear structure of the actuator shaft - provided the end of the shaft is prevented from rotating. Otherwise the cylinder and shaft just rotate together.

The Eurobricks forum has a thread detailing the differences between the various iterations of the linear actuator, with the following images of the internal components as they got updated based on customer feedback:

comparison of the old and new shaft ends

comparison of the old and new orange clutch component

* Have you considered donating to the Internet Archive?

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