space or combustion chamber 13 is effected through a fuel line 12 1 12 2 12 3 from a fuel reservoir or fuel source 11 a metering device designated in its entirety by 20 is arranged in the fuel line 12 1 12 2 between the fuel source 11 and the combustion chamber 13 a determined metering volume of fuel is measured by means of this metering device for each setting operation and is supplied to the combustion chamber 13 the metering device 20 is shown in the rest position in fig2 and in the fuel dispensing position in which the setting device is pressed against a receiving material in fig3 the fuel and the propellant in the fuel source 11 have a somewhat higher temperature of 25 u00b0 c ambient temperature the metering device 20 has a metering chamber 21 a displacing body 22 such as a displacing piston or displacing plunger is guided lateral to the metering chamber 21 in a guide 55 and can be moved in displacing direction 40 into the metering chamber 21 in order to move a metered volume of fuel from the metering chamber 21 into the fuel line 12 2 and then into the combustion chamber 13 fig1 an inlet 25 and an outlet 26 for fuel are arranged at the metering chamber 21 a valve device 27 such as a butterfly valve which makes it possible for fuel to flow out of the fuel source 11 into the metering chamber 21 but which prevents fuel from flowing back in the opposite direction is arranged at the inlet 25 a valve device 28 is likewise arranged at the outlet 26 this valve device 28 allows fuel to flow out of the metering chamber.