A machine for sorting objects, comprising: - two driving means moving along two closed-loop paths in two parallel vertical planes, where each path comprises a top horizontal straight section, a bottom horizontal straight section and two curved connecting end sections (12c, 12d) which join together opposite ends of the straight sections; - a plurality of carriages each having at least one horizontal support surface directed upwards, the carriages being fixed at a given interval to both the flexible driving means; - two end assemblies (18, 20) arranged at the end sections of the paths, wherein each assembly comprises two crown gears (22, 24) mounted rotatably in two parallel vertical planes, about a horizontal axis of rotation (x), and wherein each crown gear engages with one of the two flexible driving means so as to drive it around said path; - a plurality of mobile retaining units associated with each crown gear (22, 24), wherein the mobile retaining units each have an engaging means or seat for retaining a rigid element rigidly connected to the carriage along said semicircular section (26a, 28a) so that, along each of the end connecting sections (12c, 12d), each carriage performs a rotary/translational movement with respect to the axis of rotation (x) of the pair of gear wheels of the associated end assembly, thus keeping the support surface horizontally oriented; characterized in that - the driving means are flexible; - each plurality of retaining units circulates along a vertical closed-loop path (26, 28) which comprises a semicircular section (26a, 28a), the retaining units of each plurality being spaced from each other by a given interval; - each semicircular section (26a, 28a) of the closed-loop paths is displaced longitudinally with respect to a corresponding semicircular section (12c, 12d) of an outer periphery of the associated crown gear. - two driving means moving along two closed-loop paths in two parallel vertical planes, where each path comprises a top horizontal straight section, a bottom horizontal straight section and two curved connecting end sections (12c, 12d) which join together opposite ends of the straight sections; - a plurality of carriages each having at least one horizontal support surface directed upwards, the carriages being fixed at a given interval to both the flexible driving means; - two end assemblies (18, 20) arranged at the end sections of the paths, wherein each assembly comprises two crown gears (22, 24) mounted rotatably in two parallel vertical planes, about a horizontal axis of rotation (x), and wherein each crown gear engages with one of the two flexible driving means so as to drive it around said path; - a plurality of mobile retaining units associated with each crown gear (22, 24), wherein the mobile retaining units each have an engaging means or seat for retaining a rigid element rigidly connected to the carriage along said semicircular section (26a, 28a) so that, along each of the end connecting sections (12c, 12d), each carriage performs a rotary/translational movement with respect to the axis of rotation (x) of the pair of gear wheels of the associated end assembly, thus keeping the support surface horizontally oriented; characterized in that - the driving means are flexible; - each plurality of retaining units circulates along a vertical closed-loop path (26, 28) which comprises a semicircular section (26a, 28a), the retaining units of each plurality being spaced from each other by a given interval; - each semicircular section (26a, 28a) of the closed-loop paths is displaced longitudinally with respect to a corresponding semicircular section (12c, 12d) of an outer periphery of the associated crown gear. - the driving means are flexible; - each plurality of retaining units circulates along a vertical closed-loop path (26, 28) which comprises a semicircular section (26a, 28a), the retaining units of each plurality being spaced from each other by a given interval; - each semicircular section (26a, 28a) of the closed-loop paths is displaced longitudinally with respect to a corresponding semicircular section (12c, 12d) of an outer periphery of the associated crown gear.