Wheels on luggage

New ideas come hard. An anecdote from Robert Shiller's new book, The New Financial Order, brings this home:

[from a footnote - Ben] Sadow managed to talk to a vice president at Macy's, who agreed in the early 1970s to start selling the luggage. The suitcases did indeed sell, and set off a major trend, even though Sadow's initial model, with fur tiny wheels, was unstable. If one walked fast while pulling it, the suitcase wobbled from side to side and sometimes developed a rocking cycle with increasing amplitude unilt the suitcase fell over sideways. Since the suitcase in its normal upright resting position tended to be low relative to one's hand, the handstrap had to be fairly long, and because it was flexible, did not allow any control of side-to-side wobble. One tried walking in a bent-over position to keep one's hand closer to the suitcase for better control, which was uncomfortable and still mostly unsuccessful in controlling the wobble. [end footnote]

Sadaw's suitcases were a big improvement over suitcases without wheels, but they tended to wobble and fall over when pulled. The next great advance did not come until nearly twenty years later when a Northwest Airlines pilot, Robert Plath, invented a suitcase with two wheels widely spaced, so that the suitcase rolls along sideways with a wide axel between the two wheels. This, combined with a rigid retractable pulling handle finally yielded a stable, easily pulled suitcase that can also be used as a platform for other articles. He called it the "Rollaboard."