Commonly known wheeled carrying cases include a substantially rigid frame providing side walls of the case, and front and rear major walls that are supported by the frame, at least one of the major walls including a zippered attachment to adjacent ones of the side walls.
Wheeled carrying cases are also well known in the art that include a handle that can be telescopically extended, or retracted into, the body of the case at one of the side walls thereof, and, wheels provided at the opposite side wall of the case that can roll over a ground surface, such as the floor of an airport terminal, or, a passenger aisle of an aircraft.
While this arrangement is admirable for relatively small articles of luggage, it poses a problem in the event that a large and heavily loaded article of luggage is involved.
While such large and heavy articles of luggage easily can be stored in the luggage compartment of an automobile or other form of conveyance, when it is necessary to transport the article of luggage to some other location, a problem arises in providing adequate stability for the article of luggage when being wheeled on a ground surface, this being due to the fact that during wheeling of the article of luggage, the article of luggage must be held in an inclined position. In that position, the center of gravity of the case is displaced laterally of the ground engaging wheels, is located between the handle and the ground engaging wheels.
This can constitute a source of discomfort to the person towing the article of luggage, who is then required to exert sufficient force to support the handle, which at the time the article of luggage is positioned in the inclined position relative to the vertical for towing, can exert a considerable downwards force on the handle, that downwards force being resisted by the grasp of the user's hand.
Further, depending on the physical height of the person towing the article of luggage, the condition exists that a relatively shorter person will be subjected to a much greater force, due to the greater inclination relative to the vertical of the article of luggage and the fixed position of the handle relative to the article of luggage, than would be a taller person, who conveniently can hold the article of luggage at a lesser angle of inclination relative to the vertical during towing of the article of luggage.
As will be appreciated, the wheels on which the article of luggage is towed act as a fulcrum about which the article of luggage angles relative to the vertical when moved from the vertical position to the inclined towing position. Further, the greater the angle of inclination relative to the vertical, the greater becomes the spacing of the center of gravity relative to the towing wheels providing the fulcrum, the center of gravity then being displaced laterally of the vertical and laterally of the axis of the ground engaging wheels.
One manner of reducing this problem would be for the user to have packaged all heavy articles at the bottom of the article of luggage and in proximity to the towing wheels, the remainder of the case being occupied by relatively light weight articles. This, however, does not normally occur during the packaging of the article of luggage by the user. If relatively heavy articles are packaged in that end of the article of the luggage remote from the towing wheels, then, the center of gravity of the packaged article of luggage becomes even more displaced relative to the vertical plane including the axes of the towing wheels.
If the handle of the case should slip out of the grasp of the user's hand, then, the only possible situation is that the article of luggage, and its contained articles will crash downwardly onto the supporting ground surface, this resulting in possible damage to the articles stored within the article of luggage.
Another problem often encountered by travelers is having to deal with multiple articles of luggage. Even if both have wheels, it is very cumbersome to attempt to tow (or push) more than one article of luggage at a time. As well, the ability to stack one article of luggage upon another article of luggage is restricted and also adds significant weight along the extent of the inclined handle of the towed article of luggage.
For this reason, despite the generally recognized advantages of wheeled luggage, there are significant unresolved problems in use which the simple addition of wheels and a handle do not solve.