Lockable structure for a big-handle lock

A lock comprising:

• a base plate adapted to be mounted to a door and including a first opening;
• a lock core assembly mounted to the base plate and including a lock core;
• a press member including a first end extended through the first opening and a second end for manual pressing;
• a bottom plate mounted to the base plate and including an axle hole and a second opening through which the first end of the press member extends;
• a transmission assembly comprising:
• a transmission wheel rotatably mounted in the axle hole of the bottom plate and including a plurality of teeth;
• an actuating plate including a rack portion for meshing with the teeth of the transmission wheel, whereby rectilinear movement of the actuating plate causes rotational movement of the transmission wheel;
• a control plate operably connected to the actuating plate to move therewith, the control plate including a projection and a slot;
• a press-plate including a groove for releasably engaging with the projection of the control plate, the press-plate including a hole through which the first end of the press member extends for driving the press-plate, the press-plate being moved rectilinearly when the second end of the press member is pressed;
• a locking bar including a first end engaged with the lock core of the lock core assembly and a second end adapted to be engaged with a turn-button of an inner handle;
• and
• a follower disc mounted around the locking bar to rotate therewith, the follower disc including a cam for bearing against a wall defining a portion of the slot of the control plate;
• and
• a cover plate engaged with the bottom plate and including a lock core hole through which a key is inserted to drive the lock core, the cover plate including a third opening through which the second end of the press member extends.