There is provided an assembly for an engine configured for linking a piston to a crankshaft (6) of the engine, comprising a pair of primary connecting rods (1a, 1b) configured to link said piston (1) to a secondary connecting rod (2), the secondary connecting rod (2) comprises an upper portion (2a) and a lower portion (2b); a controlling member (3) having a pair of opposed guiding rails (3a, 3b) and a pair of aligned lateral pin joints (30a, 30b), the controlling member (3) is configured to receive a substantial part of the upper portion (2a) of said secondary connecting rod (2); and a controlling member (3) support element configured to enclose the controlling member (3) within a cylinder block (5) of said engine, wherein the secondary connecting rod upper (2a) and lower portions (2b) are connected to each other when a crank shaft joint (8) is trapped between two semi-circular space gaps (28) in each of said secondary connecting rod upper (2a) and lower (2b) portions.