Two-stage expansion/collapse control mechanism for use on a hand-trailable luggage case

A two-stage expansion/collapse control mechanism for use on a hand-trailable luggage case having a main wheel unit and an auxiliary wheel unit, the control mechanism comprising:

• an extendable frame provided on said luggage case, which includes an inner tube and an outer tube;
• a handle provided on the extendable frame, the handle having a button;
• a first locking device provided in the extendable frame;
• a second locking device provided at a bottom of the extendable frame;
• a first rigid pull-push device operatively coupled to the first locking device;
• a second rigid pull-push device operatively coupled to the second locking device;
• and,
• a pulling device coupled to a bottom of the inner tube for use in conjunction with the second locking device coupled to the second rigid pull-push device to control expansion/collapse of the auxiliary wheel unit;
• wherein when the button is pressed down for first-stage control, the first rigid pull-push device is lifted to pull the first locking device, allowing the inner tube to be extended out of the outer tube to a predetermined position;
• and when the button is pressed for second-stage control when the inner tube is in the predetermined position, the first locking device is further unlocked and is lifted to pull the second rigid pull-push device, allowing the second locking device to be unlocked.