I am emulating a throttle handle from a locomotive. See the diagram below for what I am trying to create.

Its a throttle handle with 9 'positions' or notches (0-8 power).

The handle will probably pivot on the potentiometer.

I need some ideas on how to create mechanical notches, so it clicks into each throttle position or the user knows when they change to a different position. I cannot find much inspiration on the web, as other similar systems seem 'sealed'

Proposed handle


A spring loaded ball in the handle and matching machined detents in the casing is a classic solution.

A raised bump, or dimple (from the other side) in a piece of spring steel can also work and can take up less space compared to a spring and ball.

  • $\begingroup$ Thanks, I already tried the detents idea, but had a welded ball go into them, but didn't feel great, but the spring loaded ball sounds good! Have you any product suggestions? $\endgroup$
    – Dan Sewell
    Dec 19 '19 at 20:55
  • $\begingroup$ Just drill a hole in the arm that fits the ball and continue until you just pierce the opposite side. Insert the ball and spring in the hole, then secure using a plate or set screw. $\endgroup$
    – Drew
    Dec 27 '19 at 1:29
  • 1
    $\begingroup$ You can also buy the spring and ball as a pre-assembled ball-detent cartridge. mcmaster.com/ball-detents $\endgroup$
    – Drew
    Dec 27 '19 at 1:31

Just buy a step switch and use it as your axle - it has the notches ready-made and costs a few dollars, at most.


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