Here's a little brochure I picked up a while back.
Just how often has your current vacuum spoken to you?
Judging from the fact that there is no suction unless the wheels are rolling back and forth the average housewife will get quite a workout vacuuming the portieres unless she has three arms. (Or a helper, as shown.)
Here is the Kenney patent referred to. They were still referencing this patent in 1967.