Most hurdy-gurdy wheels are hidden under a curved piece of wood called a wheel cover. This wheel is instead tucked away into the keybox. Wheels are rosined, like a bow would be, and should never be touched directly.

The keybox can be opened to reveal the inner workings. Each key is fitted with small pieces of wood or metal. These "tangents" are what actually press against the strings.

Note the bits of cotton wound around the strings. Cottoning the strings and adjusting the tangents are some of the things players do to tweak the way their instruments sound and feel.