This is going to be a candidly made article on this topic.

Hella make several vacuum pumps that are used on many cars as OEM. the VW/Audi for example is a Hella UP28. There are several models: UP28 and UP5.0 This needs to be setup to activate as soon as you hit the brake pedal. Most activate off of the brake switch.

VW/AUDI UP28 Part No: 8E0 927 317H

Hella UP5.0 Part No: 012377701