Patent ID: 7240525

Claim:
Master-keyed pin drum lock with relative master key, each pin having an inner window ( 20 ) with an outer protuberance ( 21 ) which a spring (m) acts upon and an inner projection ( 22 ) which the key( 3 ) acts upon giving rise to the movement of the pin ( 2 ). ( 2 ), the inner projections ( 22 ) are at different heights and the pins are placed so that some move in one direction and others in the opposite direction; on one of its sides the key ( 3 ) has a notch ( 31 ′) whose minimum width (d 1 ) is the distance between the maximum level (h 1 ) reached by the projections ( 22 ′) of the pins ( 2 ) which move in one direction and the maximum level (h 1 ) reached by those of the pins that move in the opposite direction; wherein: a) each pin ( 2 ) has a step ( 23 ) on its inner window ( 20 ) placed on the opposite side to that of the inner projection ( 22 ′); b) the key ( 3 ) has a double serration ( 30 ′) on the opposite side to that of the notch ( 31 ′) combined with the steps ( 23 ) of the inner windows ( 20 ′) of the pins ( 2 ′ a ), ( 2 ′ b ).