Abstract: A mechanical system with a double-sided chain, composed of a driving wheel (S1), a tensioner wheel (S2) for the chain (1), a driven wheel (S3) and a chain (1), which winds around the wheels (S1) and (S2), and engages the wheel (S3) on its outer side, characterized in that the wheel centres (S1), (S2) and (S3) are not collinear, whereas the position of wheel axis (S2) in relation to wheel axis (S1) and (S3) determines the line of operation of chain (1) and determines the optimal angle alpha between the direction of the force vector F and the perpendicular to the straight line joining the centres of tensioner wheel (S2) and driven wheel (S3), and passing through point (B) where force F1 is applied. while the value of the angle alpha is equal 15 degrees.

Abstract: A chain transmission containing two toothed sprockets, a chain and a tensioner where the center (S) of the pitch circle of the driven sprocket (2) lays outside of the circle inscribed by the part of chain (4) mating with the driven sprocket (2). Each link (5,6) of the chain (4) contains plates (7) connected by three pins (8 and 9), while the axis of one of the pin (9) lays outside of the plane determined by axes of the remaining pins (8) of the link (5, 6).