lids 2 one by one 7 denotes the pivot interconnecting the plate 12 and the mounting 5 which is positioned such that the lower section 3b of the magazine can be rotated clear when in the non operative limit position and 8 denotes releasable locking means interconnecting the carriage 14 and the mounting 5 by which the plate 12 and the bracket 6 can be anchored stably to the mounting when occupying the operative limit position such means 8 appear as a set of manually operated knobs 9 with screw shanks passing through the carriage 14 and the mounting 5 the magazine 3 also incorporates locking means 16 electric or pneumatic designed to prevent the descent of the lids 2 which comprises a rod 17 disposed transversely to the passage of the lids 2 and insertable into and across the upper section 3a of the magazine 3 through the agency of electric or pneumatic actuator means e g a solenoid valve or a cylinder at any given moment in which the need arises to interrupt the supply of lids 2 to the machine such is the case for example when lids 2 must be prevented from descending beyond the upper section 3a to allow the distancing movement of the lower section 3b 19 denotes adjustable travel limiting means fitted to the mounting 5 and engaging the carriage 14 the purpose of which is to establish the aforementioned operative limit position of the bracket 6 in the example illustrated such means 19 comprise a fixed vertical stop 24 and associated with the stop a bolt 25 positioned facing the carriage 14 in such a manner as to occasion its arrest in the operative limit position besides allowing adjustment the travel limiting means 19 will also be repositioned.