1

When the key is depressed, the jack is lifted vertically in its rail, with both plectrum and damper. The damper immediately releases the string.

2

The plectrum hits the string, generating sound.

3

The jack then meets an upper rail that stops its motion. While the key is fully pressed, the string is free to resonate.

4

When the key is released, gravity pulls the jack down through a side rail to prevent the plectrum from hitting the string again. The string is damped again.