A safety locking system is used on an exercise device. The locking system
includes a first pawl that is mounted to a pawl shaft. The pawl shaft is
movably mounted to a lock frame, which can also support a weight collar,
adapted to receive weight plates to provide additional resistance to
exercise. A second pawl is movably mounted to the lock frame and is
connected to the first pawl by way of a spring or other bias mechanism.
The lock frame limits the movement of the second pawl so as to provide a
bias of the first pawl toward engagement of the pawl to a rack provided
with the exercise device. The engagement of either pawl with the rack
restricts movement of the lock frame in at least one direction, with
gravity. If the bias spring breaks or becomes disengaged from either the
first pawl or the second pawl, the second pawl is counterweighted to
engage with the rack.