How a pianola works
The sequence of web pages which follows forms a simple animation of how a straightforward “Pianola” plays reads the roll and plays the notes.
The picture below shows the roll passing over the brass "tracker bar", with the perforations resulting in notes being played whenever the perforations uncover a hole in the tracker bar. Air can then enter the hole in the bar and operate the mechanism, as explained below.
The system runs on suction (partial vacuum) which in a conventional pianola is created by pumping the foot pedals. To play loudly, pump hard, to play softly, pump less hard. The picture below shows inside a typical player piano, and shows the main components.
The sequence of images below show what happens behind the scenes as the mechanism causes the notes to operate. Make sure you can see the captions above the images, click the > and < arrow buttons (or click on the relevant dot below the image) to move forwards and backwards through the sequence. (Note: this sequence is best viewed on a laptop or desktop computer, it is not optimised for mobile devices or tablets).