Apparatus for feeding a fluid medium acting as an electrolyte, especially a fuel

In an apparatus for feeding a fluid medium acting as an electrolyte, especially a fuel, comprising a housing having an inlet opening and an outlet opening for the fluid medium, an electric drive motor located in the housing and having an armature spindle, and a pump mounted in the housing in working connection with the electric drive motor, said electric drive motor having a commutator device, said commutator device including a commutator having contacting surfaces mounted on the armature spindle of the electric drive motor, at least two contacting brushes engaged with said contacting surfaces of the commutator and prestressed spring means associated with each of said contacting brushes, each of said contacting brushes being urged against said contacting surfaces by action of the prestressed spring means, the improvement wherein said prestressed spring means comprises a leaf spring (42,44) made of synthetic carbon and having two ends, one end (46) of which is held fast against the housing and another end (72) of which carries one of the contacting brushes (38,40), each of said contacting brushes (38,40) has a protruding portion (50) and each of said leaf springs (42,44) has a throughgoing opening (52) in which the protruding portion (50) engages, and wherein the leaf springs (42,44) have regions contacted by the fluid medium flowing during operation including an electrical connecting point (64) of the leaf springs to a conductor (30) supplying current to the leaf springs and also transition regions (75) between the leaf springs and the contacting brushes and said transition regions, said regions of said leaf springs contacted by said fluid medium and said connecting point (64) are coated with a coating material resistant to the fluid medium, and each of the contacting brushes (38,40) is soldered into the throughgoing opening (52) in the leaf spring (42,44), and the contacting brushes (38,40) have portions (55) contacting the leaf springs (42,44) when the contacting brushes (38,40) are soldered in the throughgoing openings (52) and the portions (55) are provided with a solderable layer (56) having first and second layer portions (58,60) and the first layer portion (58) covers the portions (55) of the contacting brushes (38,40) and consists essentially of copper, and the second layer portion (60) is applied to the first layer portion (58).