Fail-safe release mechanism for use with patient positioning support apparati

A fail-safe release apparatus for use with a patient positioning support apparatus having a patient support structure removably hingeably attached to a base structure by a first connection pin, the patient positioning support apparatus having a connection subassembly including first and second longitudinally aligned and spaced arms, each of the first and second arms having inner and outer sides and an array of apertures extending between the inner and outer sides, the apertures being spaced along a length of the respective arm, each aperture of the first arm being paired with an opposed aperture of the second arm, the paired apertures cooperating so as to enable receipt of one of the first pin and a second connection pin through both of the cooperating opposed apertures, the received one of the first and second connection pins having an orientation transverse to a longitudinal axis of each of the first and second arms when received in a corresponding pair of the paired apertures;

• the fail-safe release mechanism comprising:
• a) first and second locking members, each locking member being attached to the outer side of a corresponding one of the first and second arms, each of the locking members having:
• i) an inner surface slidingly engaging an outer surface of the respective one of the first and second arms;
• ii) a top end with a U-shaped notch;
• iii) an array of through-bores downwardly spaced from the notch and also spaced along a length of the locking member, the through-bores being spaced so as to be alignable with the apertures of the respective one of the first and second arms to which the locking member is attached;
• and
• b) the first and second connection pins receivable in upper and lower pairs of the paired apertures of the first and second arms, respectively, each pin including at least one circumferential key member portion, wherein the first connection pin joins the first and second arms;
• wherein
• c) disposition of the second connection pin in the lower pair of the paired apertures causes one of the U-shaped notches of the locking members to matingly engage the at least one key member portion of the first connection pin, preventing release of the first connection pin until the second connection pin is released.