"Tim" wrote in message
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"Buerste" wrote in message
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I have some air circuits that are controlled by cams that actuate manual
air valves that look like limit switches with roller arms that follow the
cam. Would I be better off with electric limit switches on the cams and
use electric air valves? The cam rotates at 120 rpm. The dwell on the
switch is 45 degrees.

I do have to replace the air switches every 2 years or so.

I will NOT install a PLC or anything more complex.

I have a similar application coming up and will need to use electric
relays to control air valves or air piloted valves to control air
valves. Which is more reliable? I do have really clean, dry air.

Bill's post made me think of this.


Have you carefully considered the profile of your cam? Adjusting things
for minimum movement, and ramp angles the minimize the speed of the roller
arms could help.

How many cycles do you make in two years? What is the pressure and
diameter of the air line. I would think a roller tip micro switch and a
quality relay should last for millions of cycles.




Hmmm, I'd say an average of 28,800,000 in 2 years. Air line is 1/4" Nylon
at @100 psi.