Device for cooling the bits of cutting machine

A device for cooling the bits of a cutting machine comprising a nozzle, arranged adjacent the bit, for the cooling water to be ejected under pressure and to which nozzle the water supply can be interrupted by means of a shutoff valve assembly which includes a valve member movable within a valve housing, the bit being supported on a bit holder for limited axial shifting movement under the action of the cutting pressure against a restoring force provided by the force of a spring and the water pressure and the shutoff valve assembly being coupled with the bit by a coupling member such that the shutoff valve opens on a shifting movement of the bit in direction of the cutting pressure, the device being characterized in that the restoring force loading the bit in opposite direction to the cutting pressure is rated such that this restoring force is at least 3000 N and is only overcome with a uniaxial cubic compression strength of the rock to be cut of at least 20 N/mm.sup.2, the spring being supported against an adjustable abutment so that restoring force can be adjusted.