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.
To clarify, I mean the symbols highlighted in green: