curve 54 in the requisite actuation force after the valve has been connected fully through flow forces are no longer definitive as the curve 54 in the range b 1 shows upon an electrical actuation of the solenoid arrangement 1 by a supply of current to the coil 19 the following procedure takes place from a terminal position at the closure piece 11 or from contact with the tappet 15 u2014 as shown in fig1 u2014 the armature 13 begins to move in the direction of the pole core segment 5 the motion begins in the range b 6 or at the transition from the range b 5 to the range b 4 u2014 in this case contact with the tappet 15 occurs u2014 with initially low force as indicated by the line 52 the range b 3 is the portion of the course of motion at which the annular edge 40 of the armature 13 crosses over the boundary line 42 with the collar between the annular edge 40 and the boundary line 42 there is a high density of magnetic field lines in the working air gap when the armature 13 with the annular edge 40 plunges into the collar 33 a pronounced decrease occurs in the magnetic field energy present in the working air gap as a result the characteristic curve 52 rises steeply from the range b 4 to the range b 3 once the armature 13 has.