Small Remote Mechanical Actuation/Actuator?

[CPosner]

Attached is a sketch of what I'm trying to accomplish...A thumb sized push button remotely mounted to actuate a locking pin up and down with the button up and down. I've thought about using a push-pull control cable, but I think my bending radius is too tight. I'm possibly looking for a simple/compact part or off-shelf part to accomplish the 90 deg turn for my actuation. Another thing I've thought about is using some small hydraulics, but I haven't found anything simple from searching. It's got to have low friction, easy to actuate, and spring back into position.

Note: I have very little access in the connection of the tube to the rectangular section.

Thanks!

 

[hydtools]

Can you make the 90-deg a radiused corner? Use a string of balls with a spring pushing them to return the button up. Put a conical end on the 'output' pin to act as a cam for the ball. Or a spring to push the output pin up.

Ted

 

[MadMango]

Not sure how much travel you need, but it looks like a trapezoidal cam with a return spring could work. The button would have a plunger that hits one side of cam and drives it forward. The other end of the cam would contact the pin and drive it down.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[CPosner]

Interesting idea. I can insert a smaller radiused tube with the balls into the joint. It's about 5' end to end. I'm concerned assembly might be tricky with that. Only the balled tube would be at the connection 90?

 

[CPosner]

If I go with a cam approach, any recommendations on steel grade for the sliding surfaces. I want to avoid heat treating. Maybe some kind of wear plates?

 

[MadMango]

How much force does the pin need to actuate?
How is the duty cycle?
What is the expected service life?
What is the working environment?

These factors will determine your material selections.



"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[CPosner]

The axial force is negligable. I need to raise and lower the pin into a fixed locating hole. The pin will work in shear to stop my assembly from rotating. Duty cycle low...but let's just say it should be maintenance free(<20years).

Working environment is a an indoor/outdoor covered area near ocean. So we have ocean air exposure and vast temperature change though seasons.

Stainless other components in this assembly are probably going to be stainless and aluminum.

 

[israelkk]

CPosner

We still do not know how much will be the maximum torque that your rotating assembly will see. This torque will give the "shear" force on the pin (deneds on the didtance from the opin to the axis of the rotating assmbly). Since the pin must be "guided" reaction forces will apply on the pin by the guides. Those reaction forces multiplied by the coefficient of friction must be overcomed by the "push" botton mechanism. Before you will know all those parameters you will not be able to receive an intelligent answer.

Added to this, how much will be the pin travel?
Are there weight limitations?
How much travel is allowed for "push" botton?

Did you try to use bicycle push/pull cables (that shift the gears) with a return spring on the pin?

 

[MadMango]

I've done similar actuation for the transportation industry, under carriage of highway coaches. Fairly severe environment, with a service life beyond 7-10yrs. I would think the cam could be some acetal/delrin material with the plungers made of 300 series stainless.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[gerhardl]

Suggestion:

Both press button and pin with springs to push back into original position when released should be easy and/or standard products.

Delrin/SS combination for cam and pin seems excellent.

Suggestion for elastic but strong and stiff enough mechanical connection between cam and pushbutton: plastic material bendable slim 'rod', radius and sideways guided by metal rings or eyebolts or parts of bended metal tube inside the larger tubes.