Lever Espresso Machines
I first started working on lever machine eight months ago in a small coffee bar placed in the front of a men’s cloths store called Present on Shoreditch High Street, London. In Present we use a Victoria Arduino two group Athena Leva. I knew little of it when I started apart from the fact it made a lovely coffee but it was soon brought to my attention by Gwilym that the machine works very differently than other more conventional espresso machines. Since then I have continued to work for Gwilym at Present and other Prufrock ventures on a number of espresso machines, none of which I enjoyed as much as that lever machine.
Recently we have been lucky enough to get our hands on a Kees van der Westen machine called the Mirage. A three group machine placed in a quiet shop located in west London that has allowed me to spend more time understanding how lever machines work and why they make such lovely coffee. I became more informed as I started taking bits apart, it was so helpful to me so I decided to photograph the workings of the group head to share with anyone that finds themselves here…on my blog.
For those that were curious (baristas and otherwise), I hope this helps.
Enjoy!
I started by removing the screws on the machine seen in the picture below. This removed the side panel allowing access to the inside of the machine.
Once removed I can gain access to three valves that gives me the ability to stop water flow to individual group heads. This will allow me to remove a group while the machine remains in working order with the ability to make coffees with the removing two groups. In the picture below I have stopped the water flow in the right group by shutting the valve labeled ”R”.
Once this is done I then have to drain water in the machine between the valve I have turned and the group head. Taking apart a group head that contains hot water will end in tears, to avoid this I pulled the group lever down fully. This flushes the water through the group, exiting the shower screen as if brewing. Once drained the water will stop flowing as shown in the picture below.
I can now lift the lever group from the machine by removing four screws in the middle on the group head.
The picture below shows the exposed lever group. The base (on the right) is fixed to a piston the runs through the inside of the spring, this piston is attached to a joint at the base of the lever. When the lever is pulled downwards the piston pulls the base(on the right) towards the lever handle (left). This compresses the spring. Lifting the lever back up releases the compressed spring.
The below picture shows the housing for the lever group with the group removed. You can see the shower screen fitted to the base. Below the shower screen is where the coffee ground sits in a portafilter.
From the side.
And from above
When the lever is pulled down the piston is raised. This creates a space between the base of the piston and the shower screen (pictured above). This space is filled with hot water. Releasing the lever upwards allows the compressed spring to push outwards, against the body of water which passes through the shower screen and through the coffee ground.
Effectively what we have is a very even cylinder of water the same diameter of the ground coffee puck being forced straight downwards through the coffee using the force of a spring resulting in espresso extraction.
Below I am going to post a series of pictures. The first shows the base of the piston base with the group assembled
The shower screen fitted.
The spring being released and pushing the piston base, forcing water through the shower screen. (Notice how evenly the water is delivered. An even cylinder of water passing straight downwards onto the coffee makes so much more sense to me than other water delivery methods.)
A portafilter is fitted containing ground coffee. The water passes through the coffee extracting the final espresso beverage.
I think that about wraps it up. A basic and brief explanation to the best of my knowledge on the workings of a lever group.
