Linear Actuator Clicking

[SNIPE]

Hi,

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:

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

 

 

Edited July 11, 2017 by SNIPE

[aminnich]

The "clutch" in the actuator is not as strong as the white clutch gear. That is your problem 

[SNIPE]

3 minutes ago, aminnich said:

The "clutch" in the actuator is not as strong as the white clutch gear. That is your problem 

I don't understand what you mean. The white clutch gear's clutch is not even doing anything when the LA starts clicking, it is just acting like a regular 24 tooth gear.

I don't know how it's 'stronger' and nor do I know in what respect is it stronger. I assume you mean it can handle more torque which I doubt since it is not triggering.

Edited July 11, 2017 by SNIPE

[aminnich]

The actuator's clutch engages before the white clutch, it can not handle as much torque. So because of this, the actuators clutch engages so that is why the whole clutch acts as a 24t gear. 

For the white clutch gear to activate, you would need enough resistance between the output of the white clutch gear and the input of the actuator. 

I hope that makes sense 

[agrof]

Is it the clicking noise what nerves you? Technically I don"t see any reason to make it extra complicated just because of the internal clutch of the LA, even further I would say it is a bad design decision to cover a "non-issue" with unnecessary bulky mechanism.

In my opinion your solution is great, works, the clicking is normal. Another option would be to replace the LA: use clutch gear + worm gear, something like this:

[Lipko]

The biggest problem with the white clutch gear is that its resistance is not consistent. Maybe you can choose one that eliminats the clicking, or makes the mechanism too weak, or doesn't eliminate clicking.

[ColletArrow]

I can't see what the problem is here. The mLA gets to the end of it's travel, and so its internal clutch engages, creating the clicking sound and slight jerks in the actuator. The wheels are in the correct position, and all seems fine.

Is the problem that you don't want the mLA's clutch engaging, but would prefer the white clutch gear? If so, what is wrong with the mLA's one? Surely they both do the same thing?

[doug72]

The clicking indicates the L.A. has reached the end of its travel or the load is too heavy, so then switch off the motor until you need to reverse the unit - simple.

Edited July 12, 2017 by Doug72

[SNIPE]

The problem was when the LA started clicking it caused vibrations which jolts the arm in which the wheels are connected.

Originally it was overly bad but after gearing it down it is not as bad. Ill try a worm gear and white clutch gear or just live with the LA's.

A pneumatic solution is probably not great.

I in the mean time have managed to make it smaller (8x5X2) when folded up.) excluding the motor and gears.

I forgot to mention that there will be shock absorbers  for the wheels too.

Thanks for the replies.

 

EDIT

I tried a few worm gear mechanisms but the small LA is still smaller, and after removing the gears and directly adding a PF M motor it is alright now, I also added the suspension and simplified everything.

also the worm gear method can accidentally be knocked and then it retracts unless you add the white clutch gear to the same axle as the worm gear and have the motor drive the clutch gear with an 8 tooth gear the worm gear can then drive an 8 tooth gear also.

 

 

 

Edited July 13, 2017 by SNIPE