What is a Piston Machine in Coffee? Exploring the Classics of Espresso Brewing

A piston machine, also known as a lever espresso machine, is a classic and elegant coffee brewing device. This manual brewing method harks back to the early days of espresso-making, long before the advent of modern semi-automatic and super-automatic machines. Piston machines offer a unique and hands-on approach to crafting espresso shots, allowing baristas to have full control over the brewing process.

Exploring the Mechanics of a Piston Machine

Below, we delve into different aspects of the piston machine and its operation:

The Lever System

One of the defining features of a piston machine is the lever system that controls the brewing process. This lever serves as the main mechanism to create pressure and extract flavors from the coffee grounds. Lever machines typically consist of the following components:

  • Reservoir: A water reservoir where fresh water is filled for each shot.
  • Grouphead: The portafilter, basket, and gasket assembly where the coffee grounds are placed.
  • Lever: The lever that the barista pulls down, activating the brewing process.
  • Piston: The component that connects to the lever and generates pressure to force water through the coffee.
  • Boiler: The heating element that provides hot water to the system.
Component Function
Reservoir Holds water for each shot
Grouphead Holds coffee grounds
Lever Main control mechanism
Piston Generates pressure
Boiler Heats water

The Brewing Process

When a barista operates a piston machine, they go through a multi-step brewing process:

  1. Filling the reservoir with fresh water before each shot.
  2. Adding coffee grounds to the portafilter basket and tamping them evenly.
  3. Engaging the lever, which lifts the piston and relieves the pressure on the coffee bed.
  4. Lowering the lever slowly and applying downward pressure to extract the espresso shot.
  5. Monitoring the extraction visually, timing it, and adjusting the lever pressure if necessary.

The Advantages of Piston Machines

Piston machines offer unique advantages that appeal to coffee enthusiasts:

  • Control: The lever system allows precise control over the brewing process, enabling fine adjustments to extraction time and pressure.
  • Temperature stability: Lever machines often have large, stable boilers, ensuring consistent water temperature during brewing.
  • Aesthetic appeal: The elegant design and retro charm of piston machines can enhance the ambiance of a coffee shop or home espresso bar.
  • Craftsmanship: Piston machines are often handcrafted and built with high-quality materials, showcasing the artistry and craftsmanship involved in traditional espresso brewing.
  • Minimal maintenance: Compared to more complex modern machines, piston machines have fewer components and simpler mechanics, reducing the need for frequent maintenance or repairs.


Despite the emergence of advanced espresso machines, the piston machine continues to captivate coffee lovers with its timeless appeal and hands-on brewing experience. Its enduring popularity is a testament to the artistry and passion behind the perfect espresso shot.