Abstract: The invention relates to a device (1) in connection with a floor cleaning machine functioning with liquid. According to the invention a combined hub (5) for supporting a brush/disc (6) of a floor cleaning machine has three functions, viz. A: as a hub for a brush/disc for holding the same, B: as a distributor for the distribution of liquid to said machine, radially from the outside towards the centre of the hub, and C: as a distributor for the distribution of vacuum to said machine in order to suck up washing liquid from the machine.

Abstract: The inventive pumping system includes at least two parallel-working pumps or compressors, at least one of which is operable as either a pump or a turbine in one or both directions, its drive motor being also capable of operating as a generator so as to feed electrical power back into the electrical network to which it is connected when necessary. At high fluid flows all the pumps or turbines act as pumps to cause the fluid medium to flow in one direction, whereas as low fluid flows the normal-acting pump or compressor operates at a relatively high energy-efficient speed while the excess flowing fluid medium is caused to flow in a return fashion through the outer pumps or turbines such that they act as turbines and thus generate electrical energy for feeding back to the electrical network to which it is connected.