Abstract: An internal combustion engine including one or more pistons, each of which is mounted to reciprocate in a respective cylinder and is pivotally connected to a connecting rod which is connected to a respective crank on a crankshaft, characterized in that the connecting rod is pivotally connected to one end of an elongate link member which is pivotally connected to the associated crank at a position intermediate its ends and whose other end constitutes a rod which is restrained by a mounting such that it may pivot about a pivotal axis parallel to the axis of the crankshaft and may move in a direction parallel to its length.