200th Anniversary of Érard’s Double Escapement Action

In 1821 Sébastien Érard patented a new piano action – the “double escapement”. The importance of this development cannot be overstated. It was the birth of the modern grand piano action, and in essence, is used by virtually all piano manufacturers to this day.

diagram of Érard's double escapement action
Sébastien Érard’s double escapement action, shown here when the key is played and held

The “action” of a piano is the mechanism that translates the downward pressure of the fingers on the keys into a movement of the hammers towards the strings. But it’s a lot more complicated than that!

When a key is pressed the hammer must be propelled at the strings, but the link between hammer and key must be broken. The “escapement” allows the mechanism to reset, making it ready to play that note again.

It’s a bit like throwing a ball upwards in the air. Once you’ve released the ball, you have no control over its trajectory. But you are free to reposition your hands in order to catch it. Once caught, you are then ready to throw it up again.

In the early days of the piano, the mechanisms were, to say the least, clunky. The holy grail was to develop a reliable action that wouldn’t jam, that wouldn’t allow the hammers to bounce back up and re-strike the strings, and one that would reset quickly enabling the note to be played again.


Sébastien Érard

lithograph of Sébastien Érard

Sébastien Érard, (born 1752, Strasbourg, France) was of German heritage and had the birth name Sebastian Erhard. He started his working life as an apprentice to a harpsichord maker, but soon decided there was more future in a new instrument – the piano. In 1777 he built his first square piano, and his designs soon won favour not only with the French piano buying public but with the French king (Louis XVI).

In 1792, in order to escape the French Revolution, Érard moved to London where in 1796 he and his brother, Jean-Baptiste, built their first grand piano. They subsequently set up factories in both London and Paris.

studio photo of one of Érard's more "up-market" pianofortes.
A grand piano by Erard Frères, made in 1808 for King Louis I of the Netherlands (Louis Bonaparte)

Érard brought countless new ideas to the design of pianos, and also to harps. However, the double escapement action was his greatest legacy. He is also credited with inventing the agraffe. This was originally a small staple, but evolved into a metal stud with holes through which the strings are threaded. These hold the strings firmly in place improving tuning stability and enhancing the tone. He was also the first maker to fit pedals to the piano.

Sébastien Érard died in 1831.


Double Escapement

In 1808 Érard patented his first repetition action, but this was considered somewhat lacking. It wasn’t until 1821, that he perfected the mechanism. At the heart of his new design was the repetition lever — ident (5) in the diagram below.

annotated diagram in closeup of the double escapement action
Close-up of Sébastien Érard’s double escapement action shown here when a note has been played and held

Early escapement actions were notoriously sluggish. They were slow to reset and prone to jamming and hammer bounce, especially if the note was held. This made it impossible to then quickly replay that same note. Érard’s new action solved this problem by facilitating a partial reset.

The mechanism uses a check (1) to catch the hammer assembly (2) immediately after it has struck the string and before it returns to its initial rest position. When the key is subsequently released, the jack (4) instantly re-engages under the hammer (at point (3)), and the note can be replayed without having to wait for the hammer to fall all the way back to its start point. Note: the red dots indicate pivot points.

At first, this “double escapement” action, with its intricate arrangement of springs (shown in yellow) and levers was felt to be too complicated to manufacture and not to be durable. But Érard’s critics, primarily the English piano makers of the time, were wrong. It was both sturdy and reliable, and it delivered.

a model showing the double escapement action of a grand piano
The double escapement action of a modern grand piano

By the latter half of the 19th century, virtually all the major manufacturers had adopted Érard’s principles.

Although this development might seem just a small element in the overall structure of the piano, the introduction of this action transformed the instrument’s playability. Its importance cannot be overemphasised. And today, despite minor improvements, we are still using Érard’s remarkable design.

see also: The Queen’s Piano.


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