a smaller compensating vessel in accordance with yet another embodiment of this invention this smaller compensating vessel 21 is also only shown in dashed lines in fig1 independently of whether an external container 20 or an internal container 18 integrated into the metering cap housing 1 for the second component is used the container 18 or 20 communicates indirectly or directly with the end 22 of a feed line 23 at the aspiration side the feed line 23 extends from the end 22 at the aspiration side through a gear pump 24 to the end 25 at the outlet side in the area of the mixing chamber 10 the means for conveying and metering the two components are shown in fig3 and 4 two shafts 30 extend through the metering chamber 9 wherein one shaft is designed in one piece with a metering rotor 31 while the second metering rotor 32 is clamped angularly fixed to the second rotor shaft by a stud screw 32 the metering rotors 31 as shown are preferably of a two bladed form this embodiment is preferred for viscous components in particular however if the quantitatively larger main component is more fluid multi bladed metering rotors are preferred one of the rotor shafts 30 terminates in an output journal 33 having for example a square cross section on which one of the two gear wheels 34 is seated fixed against relative rotation while a second gear wheel 34 39 mated with this gear wheel 34 meshes with it and thus.