(57) A lock assembly comprises a casing (1), a locking bolt (2) movable between an extended,
locking, position in which the locking bolt projects out of the casing and a retracted,
released, position, a drive including a drive member (14) for driving the locking
bolt (2) into the retracted, released, position, and a coupling member (6) adjustable
between a first state in which the coupling member is effective to transmit the drive
from the drive member (14) to the locking bolt (2) to move the locking bolt from the
extended, locking, position into the retracted, released, position, and a second state
in which the coupling member is not effective to transmit drive from the drive member
to the locking bolt. The coupling member (6) is biased into the second state but is
arranged to adopt the first state when the locking bolt (2) is in the extended, locking,
position and to remain in the second state as the drive member (14) drives the locking
bolt into the retracted, released, position. The assembly further includes an auxiliary
bolt 10 which is mounted in the casing for movement between an extended position in
which the auxiliary bolt projects out of the casing and a retracted position, and
a bolt retaining device (11) for retaining the locking bolt (2) in its retracted,
released, position, when the auxiliary bolt (10) is in its retracted position.
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