Piano Resource Center - Steinway Pianos at M. Steinert & Sons Boston

What Is Piano Action? A Beginner’s Guide to Piano Mechanics

Written by Brendan Murphy | Oct 17, 2025 2:24:18 PM

Piano action refers to the network of levers, hammers, springs, and dampers that responds to your keystrokes. It is the connection between your hands and the voice of the piano.

The responsiveness of this system determines how expressive, controllable, and enjoyable a piano is to play—making action quality a critical factor when purchasing any piano.

How Does a Piano Action Work?

Here’s a simplified look at what happens when you press a key:

  1. The key acts as a lever, initiating the motion.

  2. A hammer is propelled to strike one or more strings.

  3. A damper lifts off the strings while the key is held, letting them vibrate freely.

  4. Once the key is released, the hammer returns and the damper falls back onto the string, silencing it.

One of the unsung heroes of this process is a mechanism called escapement, which ensures the hammer falls away immediately after striking so it doesn’t mute the note. Grand pianos often feature double escapement systems (invented by Sébastien Érard), which allow faster repetition of notes—a vital feature for expressive or technical playing.

Upright vs. Grand Piano Action

Upright Piano Action:

In upright pianos, the action is mounted vertically. Because gravity alone can’t reset the hammer, springs are used to return the components to their resting positions. This works well, but generally results in slightly slower repetition and less dynamic control compared to grands.

Grand Piano Action:

In contrast, grand piano action lies flat, and gravity resets the hammer naturally. Combined with double escapement, this layout allows for quicker note repetition and more responsive touch. It’s one reason grand pianos are favored by serious pianists and performers.

Why Piano Action Matters

  1. Touch Sensitivity: It affects how expressive and dynamic your playing feels.

  2. Speed and Repetition: High-quality action enables rapid playing and consistent sound.

  3. Learning & Enjoyment: An inferior action can limit progress or cause frustration.

  4. Durability & Value: Better actions last longer and require less frequent servicing.

Digital pianos increasingly aim to simulate acoustic piano action. If you’re evaluating the best digital pianos, be sure to explore weighted key actions or graded hammer action for a more authentic feel.

Notable Piano Action Brands

Renner (Germany):

Renner is widely regarded as one of the world’s premier manufacturers of piano actions and action parts. The company produces a variety of action designs tailored to the specifications of many leading piano makers, including Fazioli, Mason & Hamlin, and Steinway. In 2019, Steinway & Sons acquired Renner.  Following the acquisition, Renner produces proprietary actions solely for Steinway, while maintaining its role as a supplier of custom action parts to other distinguished piano manufacturers worldwide.

Other Notables:

  • Wessel, Nickel & Gross (WNG): Known for carbon-fiber action parts found in the Mason & Hamlin piano and in some custom and modern instruments.
  • Kawai Millennium III: A hybrid carbon-composite action that offers exceptional speed and stability.
  • Yamaha: Manufactures its own actions of various design specifications across its upright and grand lines.

Piano Action Repair and Replacement

Over time, piano action components—made from wood, felt, and leather—can wear out. In vintage or heavily used pianos, parts like hammers, shanks, or key bushings may need replacement or full action rebuilding. This process restores the touch and responsiveness of the instrument.

Regular action regulation—adjusting key height, hammer travel, and escapement—can keep a piano feeling fresh and expressive, postponing major repairs and ensuring the player’s full musical range is supported.

Final Thought: Your Connection to the Music

Whether you’re purchasing a baby grand, an upright for your family, or comparing top-tier digital models, remember: the action is the heart of the piano. It’s the invisible interface between your hands and your sound. Investing in a high-quality action gives you more than better performance—it gives you confidence, satisfaction, and joy every time you sit down to play.

Want to feel the difference?

Connect with one of our piano consultants or visit our showroom to experience piano action firsthand across upright, grand, and digital models.