This has everyone I ask stumped. The board is a Siemens 115U CPU (6ES5943-7UA11) from the Simatic S5 rack, circa 1990's. It has some LEDs and two SPDT, O-ring sealed toggle switches on the front, one of which is an exotic ON-OFF-Momentary style. I've tried running the numbers (26-11 06xx), nothing. Tried looking through hundreds of manufacturer logos, nada. Even went to patent trademark websites and searched through countless combinations of "E3" "3E" "EE" "33" etc... nope. Can anyone confirm whom made these switches? Was it Siemens in an act of obscurity?

Siemens 6ES5943-7UA11 Mainboard

26-11 0607 and 26-11 0600

Inside they are pretty neat. Flipping the lever moves a spring-loaded ball bearing along a pointed track for the "snap" action feel. While the shaft holding the ball bearing, once it reaches position, pushes against a top and bottom set of tiny switch contacts.

  • \$\begingroup\$ It's similar to the old Siemens logo, but not quite it. Escom? \$\endgroup\$
    – winny
    Commented Dec 22, 2017 at 23:07
  • \$\begingroup\$ Maybe an old logo from e-switch? \$\endgroup\$
    – JRE
    Commented Dec 22, 2017 at 23:16
  • \$\begingroup\$ Maybe WM or MW? \$\endgroup\$
    – Tyler
    Commented Dec 22, 2017 at 23:48

2 Answers 2


Dunno about the logo, but it's a Hartmann part number.

enter image description here

There's been a lot of consolidation in the electronics industry- maybe they bought someone up before being swallowed up themselves by Phoenix Mecano.

I used to go to Electronica in München fairly frequently back in the day and was struck by the number of small (less than 1000 employees) successful family owned companies doing electronics in Western Europe.

  • 1
    \$\begingroup\$ Thank you Spehro! Just adding "Hartmann" to the 26-11 part number gets google to find their page. \$\endgroup\$
    – rdtsc
    Commented Dec 27, 2017 at 13:38

Not a proper answer, but I was interested to see if a logo search would show up anything so I created one in Inkscape and dropped it and its negative into Google's Image Search. No joy. They may be of some use to you.

enter image description here enter image description here

  • \$\begingroup\$ I tried searching for a cropped version of the photo then this rendering on google and tineye.com, but they turned up nothing. (Not surprising as tineye states that their search is pixel-based only, not correlative.) Thanks for the effort however! \$\endgroup\$
    – rdtsc
    Commented Jan 2, 2018 at 13:24

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