When the first Espresso machines (Machines that br /ewed Coffee under pressure which is "Espresso") at the start of the last century (1902) were introduced, pressure(Approx 2 bar) was produced by the machines Barista allowing just the right amount of steam and the right amount of hot water pressure to push water through coffee. This new pressurized br /ewing method made a big difference. A better exploitation of the essential oils and sugars were extracted creating a better smoother taste, using less coffee at a finer grind. It was a complicated set of valves that made the Barista a very specialized person to say the least. The importance of this specialize field remains true today although the talent requirements have changed.
It is true, that there is no substitute for good personalized service.
1940: Real Espresso
In the late 40's a new spring loaded coffee br /ewing device was invented.
The new "Manuel" or "Lever" models made even a better cup of coffee. It is at this point when the "Crema" was really created and were much easier to use. The "Lever" model used a very strong spring to create the pressure needed to make the Real Espresso we know today. The spring had to be pulled down by a rather strong person in order to engage the piston in the proper position. A slip of a sweaty hand, or Barista not paying attention would cause the Lever to slip, and was followed by a massive banging sound which could cause the safety valve to slip off its mount of the boiler. This would cause a release of steam from the boiler. The release of steam was like one of a steam engine and was quite scary. I would imagine that this is where the myth of espresso machines "blowing up" would come from. In fact, espresso machine in this era never blew up.
Fun Fact: 1950's
Automatic Hydraulic Machines are introduced by Cimbali. It is the world's first High pressure automatic dosing machine. "Gold Compass" for engineering awarded to Cimbali.
Automatic pressure is introduced in the form of a pump and motor:
This was also when a Heat Exchanger was invented for use in an espresso machine (Cimbali Patent)
Around 1960, the centrifugal or carbonator pump was invented. This new electrical device could take normal water pressure from a water line an increase it to the same or grater pressure than that of the Spring Lever "Automatically". Another advantage was a more consistent pressure. All's it needed was a motor and electric, now espresso machines had an automatic system of pressure. So although the machine automatically created pressure by the turn of a switch, the flow of the coffee had to be turned off manually or the result would be a bad tasting espresso due to over extraction.
Hence the name "Semi-Automatic" Semi-automatic are still used today.
Fun Fact: 1969
Two Companies introduces "Super automatic" machines:
Faema "X5", Cimbali "Superbar".
Mechanical automatic dosing, with Pumps introduced. These units were very reliable, and mechanical, They were prone to
failure by hard water in a short period of time.
1986, Age of Electronics (One very simple moving part added to a Semi-automatic machine)
Today the most common machines are all electronic. The machines mechanical part is very simple, and requires little to no maintenance.
These machines employ a micro-processor that controls all the aspects of the machines coffee delivery system
and Safety components.