James Dyson bought a Hoover Junior vacuum cleaner in year 1974. The Hoover became clogged quickly and lost suction over time. Frustrated, Dyson emptied the bag to try to restore the suction but this had no effect. On opening the bag to investigate, he noticed a layer of dust inside, clogging the fine material mesh and preventing the machine working properly. The machine worked well only with a fresh bag, it lost suction over time. He resolved to develop a better vacuum cleaner that worked more efficiently.
During a visit to a local sawmill, Dyson noticed how the sawdust was removed from the air by large industrial cyclones. Centrifugal separators are a typical method of collecting dirt, dust and debris in industrial settings. Such methods usually were not applied on a smaller scale because of the higher cost. Dyson hypothesised the same principle might work, on a smaller scale, in a vacuum cleaner. He removed the bag from the Hoover Junior and fitted it with a cardboard cyclone. On cleaning the room with it, he found it picked up more than his bag machine. This was the first vacuum cleaner without a bag.