A linkage-actuator for the coupler knuckle-assembly of a railway passenger car which is mounted on the coupler head directly adjacent to the knuckle-assembly, which linkage-actuator does not extend along the shank connecting the knuckle-assembly to the car proper, thereby saving considerably on space and weight. The linkage-actuator allows for both manual and pneumatic actuation of the knuckle-assembly. The linkage-actuator for the knuckle-assembly is mounted directly on the coupler head. The rotatable operating rod for placing the knuckle into its lock-set or fully open position is actuated by a pivotal plate mounted on top of the coupler head. One end of the plate is urged into its non-actuated, horizontal position by a spring, while the other end of the plate is connected to an eccentric cam that is coupled to the rotatable actuating rod of the knuckle-assembly. An air-bellows lifts the end of the plate coupled to the eccentric cam which, in turn, rotates the actuating rod, to thereby place the knuckle into its lock-set or fully thrown position.