pressure chamber 13 as a consequence there is no longer a force compensation between the end face of the stepped piston 17 protruding into the first pressure chamber 13 and the annular face 20 the stepped piston 17 begins to pump by means of the ratio between the end faces protruding into the first pressure chamber 13 and into the second pressure chamber 15 the ratio of the pressures in the first and second pressure chambers 13 and 15 is specified as soon as the pressure in the second pressure chamber 15 or in the high pressure path 10 exceeds the opening pressure of the injection nozzle 1 the injection nozzle 1 opens and the injection begins as soon as the control valve 21 is closed again a pressure equalization and force compensation takes place between the first pressure chamber 13 and the control chamber 19 so that the stepped piston 17 is moved into the position shown in fig2 in the direction of the first pressure chamber 13 by a restoring spring 29 as soon as the stepped piston 17 moves in the direction of the first pressure chamber 13 the pressure in the second pressure chamber 15 collapses and the injection nozzle 1 closes the second pressure chamber 15 is filled via a supply line 31 subjected to leaking oil pressure a check valve 33 is disposed in this supply line 31 the check valve 33 can be spring loaded as seen in fig2 or.