Abstract: A pump 11 is provided in a gear-shift mechanism, in particular a boat reversing gear transmission, in order to supply the hydraulically operated friction clutches with pressurized oil. The pump 11 sucks oil through a fine-mesh filter 19 out of the sump 21. The fine-mesh filter 19 is arranged in a separate filter chamber 12 which is connected through a suction pipe 13, 15 to the sump 21 and to the suction side of the pump 11. The two suction pipes are arranged in such a manner with respect to one another that the filter chamber 12 is always filled with oil. A dry running of the pump 11 during starting is avoided in this manner. The fine-mesh filter 19, in the form of a removable filter cartridge 20, allows the flow of oil from the inside thereof to the outside and is arranged for easy access from above.