Cylinder lock and key combination providing extra code combinations

A cylinder lock including

• a housing with a cylindrical bore, and
• a cylindrical key plug, which is rotatably mounted in said cylindrical bore and is provided with a longitudinal keyway and a number of locking tumblers, including at least one side locking tumbler having a transversely projecting finger and being mounted in an associated chamber for elevational and rotational movement therein, the rotational movement being confined between two angular end positions,
• said at least one side locking tumbler having a pair of side openings in a cylindrical surface at a back part, opposite to said finger, these side openings forming therebetween a tongue being dimensioned to cooperate with a sidebar, which is movable transversely towards a longitudinal central axis of said cylindrical bore, there being at least one spring urging the sidebar to move outwardly towards a groove in said housing,
• said sidebar having one or more recesses configured to receive said tongue of the at least one side locking tumbler upon rotating and lifting said locking tumbler into a predetermined position, the sidebar serving as a locking means for the lock but enabling the key plug to be rotated in said housing so as to release the lock when each side locking tumbler has been correctly positioned into said predetermined position,
• the tongue of the side locking tumbler being flat with opposite, mutually parallel inner surfaces and an elongated, peripheral outer surface, extending vertically in parallel to an axis of the side locking tumbler and facing the sidebar, and
• each recess in the sidebar being substantially rectangular in longitudinal section, with opposite inner wall surfaces having a mutual distance corresponding to the distance between the opposite surfaces of the associated tongue of the side locking tumbler, with a tolerance that enables the tongue, if correctly aligned elevationally and rotationally with the associated rectangular recess of the sidebar, to be inserted therein when the lock is to be released, each recess in the sidebar having right angle corner edges defining an entrance opening of the recess in a longitudinal flat surface of the side bar facing said rotatable key plug,
• wherein:
• said elongated, peripheral outer surface of said tongue of said side locking tumbler is shaped as a groove and has two parallel vertical edge portions forming a respective transition to an associated one of said opposite inner surfaces of said tongue,
• each said vertical edge portion comprises a first surface portion located substantially in a cylindrical contour of said side locking tumbler,
• each said first surface portion adjoins, via a second vertical edge, a second surface portion extending inwards in relation to said cylindrical contour,
• each said second surface portion forms a part of said groove and adjoins a bottom portion of the groove extending at a distance radially inwards in relation to said cylindrical contour, and
• one of said two vertical edge portions of said tongue will abut, with its second vertical edge, against said longitudinal flat surface of the sidebar, adjacent to said entrance opening of the associated rectangular recess, and thereby stop the tongue from entering into the rectangular recess in case the side locking tumbler is rotationally misaligned in relation to said associated recess when an incorrectly shaped key or other object is inserted into the keyway of the lock and a rotating torque is applied to the rotatable cylindrical key plug.