Editing Espresso machine (section)

===Piston-driven===
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[[File:Manual Elektra espresso machine.jpg|thumb|upright|A manual piston espresso machine made by Elektra]]

The piston-driven, or lever-driven, machine was developed in Italy in 1945 by Achille Gaggia, founder of espresso machine manufacturer [[Gaggia]]. The design generically uses a lever, pumped by the operator, to pressurize hot water and send it through the coffee grounds. The act of producing a shot of espresso is colloquially termed ''pulling'' a shot, because these lever-driven espresso machines required pulling a long handle to produce a shot.<ref>{{cite book| last =Pendergrast | first =Mark | author-link= Mark Pendergrast | title =Uncommon Grounds: The History of Coffee and How It Transformed Our World | publisher =Texere | location=London |page=218|year=2001|orig-year=1999 | isbn =1-58799-088-1}}</ref> Lever-driven espresso machines are sometimes called manual espresso machines because of this.

There are two types of lever machines; manual piston and spring piston design. With the manual piston, the operator directly pushes the water through the grounds. In the spring piston design, the operator works to tension a spring, which then delivers the pressure for the espresso (usually 8 to 10 [[Bar (unit)|bar]]; 116 to 145 [[Pound per square inch|psi]]).