Always wondered .......

[Jerryl]

About 18 years ago, I was at a GM plant watching an assembly line.
I remember watching the brake system filled in about 15 sec with some equipment (Vac and fluid supply at the master cylinder.)

Anyone know how that works?

 

[1ARUNM]

My first job at GM was filling radiators, and the machine used to do that clamped on the fill neck and evacuated the cooling system with vacuum. When it reached the desired vacuum level it would open the coolant valve and the coolant would be sucked into the system. I did a car every 45 seconds. Worked great unless you had a loose hose or one with a hole in it. You would find your leak real quick when it pressured up, and usually get a bath to boot. I still don't like antifreeze.

The brake machine is not exactly the same machine, but similar. I'm pretty sure it uses the same method.