I am looking at replacing mechanical momentary contact double pole switches with something more reliable and accurate. The switches monitor cam lobes. This is the current set-up, within the ellipse is the switch pack I want to replace. The switches are at the bottom of each finger with an adjusting screw/locknut. These old switches also have a tendency to wear over time, not just where the roller at the tip of the finger rides the cam but where the end of the adjusting screw contacts the button of the switch. Another problem is the tensioning spring holding the finger against the cam stretches over time and everything goes out of adjustment. I was thinking either a magnetic strip that sat on the cam lobe with a reed switch or a switch that wrapped around the edge of each cam with a stick on label on the edge of the cam (found some possibilties for the first option but not sure what to search for on the latter). I have 2 sets of these cams to deal with. The switches need normally open/normally closed terminals and need to handle 24 volts.

Wiring diagram, the switches are located in the right central section...

 

Do the cams have any other function other than working the switches?

If not you can add opaque flags - small bits of metal and replace the switches with three opto interrupters - http://www.vinland.com/Opto-Interrupter.html

 

beenthere, depends how dirty this machine is. Interesting looking bugger, looks like it needs a thorough lube job now and again.

 

All the cams do is change the state of the switch at specific degrees.

Set #1
A=0-270, 271-359
B=0-66, 67-185, 186-360
C=0-85, 86-242,243-360

Set #2
A=0-184,185-349
B=0-259,260-349
C=0-104,105-255

 

I think the 'opto-interrupters' is kinda what I was thinking about. A label that could be stuck on the side of the cam with the sensor changing the switch state when the label is detected.

 

As to lubrication, Converting to an optical sensor will eliminate all the need for oiling in that area. Yes tho, the large cams/followers on the left as well as similar items to the right require quite a bit of grease and oil.

 

See if this link isn't to the point - http://www.vinland.com/Opto-Interrupter.html