Rear wheel steering drive mechanism

Claim 1

A rear wheel steering drive mechanism for a vehicle having a front wheel steering system and a rear wheel steering system, the rear wheel steering drive mechanism comprising a casing, an input shaft and an output shaft journaled in the casing, the input shaft adapted to be operatively connected to the front wheel steering system for rotation thereby whenever the front wheel steering system is activated, the output shaft adapted to be operatively connected to the rear wheel steering system to selectively transmit front wheel steering system activity to the rear wheel steering system, a loose crank pin positioned within the casing, the casing having an annular groove therewithin, the crank pin received in the annular groove for movement therein, stop pin means to maintain the crank pin in an initial position within the groove during the initial portion of input shaft rotation thereby preventing movement of the crank pin in the remainder of the groove during this portion of input shaft rotation, the casing having a interior axially extending hollow cylindrical member through which the input shaft extends, the cylindrical member defining, with the casing interior surface, the groove, the cylindrical member having a pair of angularly spaced apart radially outwardly directed passageways extending from the interior thereof to the groove and located so that the entrances thereto from the groove are positioned on either side of the crank pin when the crank pin is in its initial position and the entrances thereto from the casing interior are positioned in alignment with the input shaft, a stop pin slidably received in each of the passageways, a portion of the exterior surface of the input shaft being in contact with the inner end of both stop pins, said exterior surface portion of the input shaft having a first generally circular cam surface portion operable to maintain both stop pins in a raised position wherein the outer ends thereof block the crank pin and prevent it from moving into the remainder of the groove, the input shaft having a second cam surface portion of generally less diameter than the diameter of said first cam surface portion operable to allow the stop pins to slide in the passageways to a lowered position out of blocking position with respect to the crank pin to allow movement of the crank pin into said remainder of the groove after said initial portion of input shaft rotation in either direction.