Head support that can be moved in the X direction

A head support comprising:

• a head support box that is displaceable in an X direction relative to at least one holding bar, wherein the head support box has one interlocking or frictional device on both of two opposite outer walls and has two interlocking or frictional devices on at least one inner wall, the at least one inner wall is positioned laterally inward from the outer walls and extends substantially parallel to the outer walls, first pinion and a second pinion are arranged between two interlocking or frictional devices, each pinion is configured to rotate about an axis substantially parallel to the at least one holding bar, and the pinion engages with one respective interlocking or frictional device and meshes with the one respective interlocking or frictional device.