| 摘要 |
A central vacuum cleaning system has multiple vacuum sources. The multiple vacuum sources are connected through pipes to wall valves. In use a hose is plugged into one of the valves. A handle is connected to the hose. A wand extends from the handle. Attachments such as a power brush are connected to the wand. Switches apply power from o ne or more power sources to the vacuum sources. The application of power by the switche s is controlled by a control circuit.
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