which has been introduced in this state the actuating section 44 no longer presses on the sensor 46 a fact which corresponds to a second switching state of the electrical switch 42 the switching state of said electrical switch 42 accordingly gives reliable information as to whether the door is closed or open for only when the door is actually closed does the blocking lever 30 remain in its releasing position without the keeper 16 introduced it returns at least approximately to its blocking position at any rate after the door closing device has been left alone again as an alternative to an inherently rigid blocking element the blocking element may conceivably be manufactured from a flexible material say from a piece of spring steel sheet in such a case it is possible to dispense with a separate pretensioning spring for said blocking element for the purpose of explaining the second exemplified embodiment reference will now be made to fig9 to 13 in said second exemplified embodiment components which are identical or which have an identical action are provided with the same reference symbols as before but with the addition of a lower case letter in order to avoid unnecessary repetitions the reader is referred to the above description of the first exemplified embodiment provided that nothing to the contrary arises below the exemplified embodiment in fig9 to 13 differs from the first exemplified embodiment substantially as a result of a different way of generating the spring pretensioning for the rotary member 22 a in concrete terms two helical draw springs 26 a serve to generate.