1. 
   Vacuum switch
   The internal combustion engine in a common automobile produces almost 20 inches (51 cm) of vacuum,{citation needed|date=December 2009} and this pressure differential may be harnessed for many uses. Engine vacuum is also the best direct source of information on the engine`s load.{citation needed|dat...
   Found op http://en.wikipedia.org/wiki/Vacuum_switch
   
   

Tip: double click on a word to show its meaning.