A coupling for uniformly transmitting torque from a first shaft to a second shaft while accommodating parallel, angular and/or axial misalignment between the axes of said first and second shafts, said coupling comprising:
- a first annular member having means for fixedly securing the same to the first shaft for rotation therewith about an axis of rotation coincident with the axis of the first shaft,
- a second annular member having means for fixedly securing the same to the second shaft for rotation therewith about an axis of rotation coincident with the axis of the second shaft,
- a third intermediate member having an axis of rotation aligned with the axes of rotation of said first and second annular members when the axes of the latter are aligned,
- said intermediate member including an annular portion disposed between said first and second annular members and first and second pairs of elongated generally parallel arm portions operatively associated with said first and second annular members respectively,
- each of said arm portions including a fixed end fixedly interconnected with said annular portion within the axial extent thereof and a free end,
- a first pair of connecting elements fixedly projecting axially from said first annular member and connected with the free ends of said first pair of parallel arm portions at positions related to the longitudinal extent of said first pair of parallel arm portions and the position of fixed connection of the fixed ends thereof with said annular portion so as to cause torque fixedly transmitted to said first annular member by the first shaft to be transmitted longitudinally through one of said first pair of arm portions to said annular portion under tension without longitudinal material displacement and through the other of said first pair of arm portions to said annular portion under compression without longitudinal material displacement while enabling through transverse material flexure of said first pair of arm portions the following relative motions of said annular portion with respect to said first annular member (1) a parallel linkage type substantially rectilinear movement in a first transverse direction generally perpendicular to the longitudinal extent of said first pair of parallel arm portions, (2) an angular movement about an axis extending generally in said first transverse direction, and (3) an axial movement, and
- a second pair of connecting elements projecting axially from said second annular member and connected with the free ends of said second pair of parallel arm portions at positions related to the longitudinal extent of said second pair of parallel arm portions and the position of fixed connection of the fixed ends thereof with said annular portion so as to cause torque transmitted to said annular portion to be transmitted longitudinally through one of said second pair of arm portions to said second annular member under tension without longitudinal material displacement and through the other of said second pair of arm portions to said second annular member under compression without longitudinal material displacement while enabling through transverse material flexure of said second pair of arm portions the following relative motions of said annular portion with respect to said second annular member;
- (1) a parallel linkage type substantially rectilinear movement in a second transverse direction generally perpendicular to the longitudinal extent of said second pair of parallel arm portions and said first transverse direction, (2) an angular movement about an axis extending generally in said second transverse direction, and (3) an axial movement.