On the schematic below, I'm having trouble identifying what the symbol drawn on top of motors 2 and 3 means. I've never seen anything like it. They're only present on the high-power spindle and feed motors, not on the smaller cooling pump motor.

It's an Abene VHF3 milling machine from ca 1975.

Could it be some kind of thermal switch or auxiliary winding of sorts? Tracing the lines it seems to loop through both motors and then lead to some kind of indicator light.

Abene VHF3

To clarify, I mean the symbols highlighted in green:

enter image description here

  • 2
    \$\begingroup\$ Could be a centrifugal switch symbol: mastersamuraitech.com/module-7/switches-and-relays/… \$\endgroup\$
    – Drew
    Commented Jun 24, 2020 at 21:10
  • \$\begingroup\$ They seem to go to indicator lights. Perhaps a "running" lamp? Makes sense if switches close (or open) on motor movement. \$\endgroup\$
    – rdtsc
    Commented Jun 24, 2020 at 21:27
  • \$\begingroup\$ @Drew agree, that might well be what it is. Seems odd to have all the added mechanical complexity of a centrifugal switch just to switch an indicator lamp while the motor itself is being switched w/ a 24V contactor coil that could've easily been tapped off though... All that just to see if the motor is really turning? \$\endgroup\$
    – Mels
    Commented Jun 24, 2020 at 21:36
  • \$\begingroup\$ i agree that it is a centrifugal switch ... it may be part of an overload warning system .... or simply an "up to speed" indicator \$\endgroup\$
    – jsotola
    Commented Jun 24, 2020 at 23:46
  • \$\begingroup\$ @Drew if you post your comment as an answer I'll gladly accept it :-) \$\endgroup\$
    – Mels
    Commented Jun 25, 2020 at 7:42

1 Answer 1


Looks like it may be a centrifugal switch.

centrifugal switch schematic symbol https://mastersamuraitech.com/module-7/switches-and-relays/centrifugal-switch-schematic-symbol/


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