Turnover key and corresponding cylinder lock

Claim 1

A lock system comprising: a cylinder having a first axis of rotation, said cylinder being formed with a narrow elongated key channel having a second axis of symmetry offset from said first axis; a row of first keeper pins mounted in said cylinder and movable transversely to said channel while lying in a plane perpendicular to the broad dimension of said channel and offset from said second axis, said pins having conical tips entering into said channel and being displaceable outwardly therefrom to permit rotation of said cylinder about said first axis; and a key having an elongated blade with beveled edges receivable in said channel and formed along opposite broad faces of the blade with a row of indentations offset from said second axis and adapted to receive said tips upon insertion of said blade in said channel to enable rotation of said cylinder by said key about said first axis, said key being receivable in said channel in two positions offset by 180° about said second axis from one another, said blade having a leading end formed with a respective keyway along each row of indentations and spaced inwardly from the edges of the blade, said keyways each extending forwardly from the broad surface formd with a respective row of indentations to the opposite broad surface of the blade and comprising a ramp of rectangular plan configuration and a pair of flanks converging rearwardly and toward the respective ramp, said tips being frustoconical with small bases fitting between said flanks and said flanks having a convergence corresponding to the taper of said tips, said tips beginning opposite the longitudinal plane of the channel from their mounting in said cylinder, said first keeper pins extending fully across said channel.