Heard of them but never seen one .
Quick story;
I committed the dreaded compression fault as an apprentice and never forgot it . I started in industry on maintenance, spark had me and a mech. fitter apprentii updating some awkward pneumatic /elctro valves on a machine .
I fitted a strip of the original " Choc Bloc " connectors with 24V control wiring . Everything working again until machine was halfway through it's cycle and blowing the control fuse .
Sparks left me to sort it until I'd blown a boxful of fuses ...he stepped in and showed me a couple of things I've never forgotten .
Thing (1) Stop going at it like a demented chicken ...stop & take stock .... it was fine before so what have you done thats different .... the valves , the flexibles, the
connectors .
Thing (2) Ask the operator where it stops .
Thing (3) Remove the control fuse and connect a 24V lamp across the carrier , when it lights up , thats the fault to earth .
Thing (4) OK it stops every time the cutting head needs to raise away from the steel bar .....you know which valve directs the cutting head ...the wiring is OK .... but
you've fixed the "Choc Bloc" to the machine with a 2BA pin which is too big and too tight, it shorts the terminal to earth that operates the solenoid that lets compressed air through to the head and returns it .
That was about 400 years ago .