Shifter park position brake-transmission interlock

Abstract

A shifter for an automatic transmission is prevented from shifting out of Park position when the ignition switch is on unless the service brake is applied. An articulated solenoid-operated blocking arm is positioned to selectively block movement of a locking pin to prevent the shift lever from leaving the Park position of the shift gate. A circuit, including switches responsive to ignition, service brake application and shift lever position, controls solenoid activation. A cam responsive to the shift lever release button and to the lever position controls the shift lever position switch. The blocking arm can comprise two segments joined by a hinge. In blocking position, the hinge lies on one side of the path of pin movement. If the pin release is prematurely actuated, the pin engages the blocking arm. Subsequent solenoid activation pushes the hinge overcenter so that pin force will collapse the blocking arm, enabling its movement out of blocking position by the solenoid. An alternative blocking arm is an integral plastic piece with two segments interconnected by an integral hinge or two independent segments interconnected by a hinge pin. Alternatively, the blocking arm can comprise a single segment mounted for movement by a pin-and-slot arrangement.