Linear Actuator Clicking

Question

I have just finished working on a mock-up landing gear deployment mechanism, keeping it as simple as possible of course.

However one thing that I cannot seem to get rid of, is the small linear actuator's built-in overload protector from clicking.

I have tried to add a white clutch gear meshed to an 8 tooth gear in either 3:1 or 1:3 ratios but it still clicks.

If I use a 3:1 ratio the clicking and vibrations are obviously much more rapid than otherwise.

To save space, I insisted on having a fixed, almost parallel LA rather than the typical design where the LA is also pivoting like a lift-arm.

The wheels must be retracted by 90 degrees (you'll see this if you build it/watch the video)

Does anyone have any ideas on how to eliminate this whilst keeping it simple? I tried replacing the 2 x 4 bent lift-arms with a what equates to 1.5 length lift-arms so that the LA does not fully retract and start clicking but then it does not do a full 90 degrees of movement and starts bending parts if I force it.

Here is an .LXF file and below is a video showing what I mean:

https://www.youtube.com/watch?v=TOmrNr0WwWI

I'll be able to shorten or remove some beams soon to make it less clunky.

Answer 1

As both the LXF file and the video are unavailable, I can only guess at the problem you are facing. But if the linear actuator is clicking, it means the built-in clutch is engaging, as the forces keeping the actuator from moving are too large. This can't be solved by adding a clutch gear (even with gearing), as if the newly added clutch gear is rated to slip at a lower force, it will slip before the linear actuator, and if it starts to slip at a larger force, the linear actuator will still start clicking first.

The best way would be to redesign the linkage to require less force to operate, but it might not be possible in your case:

To save space, I insisted on having a fixed, almost parallel LA

This rules out another possible solution: doubling the linear actuators involved, as two parallel linear actuators will start clicking at a doubled force.

The only remaining advice I can give is to reduce the forces involved, either by attempting to redesign the linkage, or incorporating other means to provide force to assist the linear actuator, like springs, rubber bands, torsion bars, flexible elements, pulleys or even counterweights.