(57) A lock set particularly for use in access-control systems comprises a cylinder unit
1 based on a standard pattern which is key-operable from the outside and operable
by a thumb turn from the inside. In place of the normal thumb turn, however, the cylinder
unit has a coupling 10 into which fits a shaft 21 from a motor unit 2 mounted to the
inside face of the door. In normal operation the motor 20 is actuated to unlock and
then relock the door by turning the shaft 21 in opposite directions to correspondingly
turn the cylinder cam 14. The extent of this movement is controlled by a limit/reversing
switch 23 actuated by a cam 24 on the shaft 21. Operation from the outside can also
be effected by key-operation of the cylinder unit and for emergency operation from
the inside a thumb turn 7 is provided on the accessible end of the shaft 21. The permanent
connection between the cylinder cam 14 and the shaft 21 means that the limit/reversing
switch 23 is always in the correct position for subsequent operation of the motor
20 in the appropriate sense irrespective of whether the last locking or unlocking
action was accomplished with the motor, thumb turn or key.
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