Particularly in so-termed Electrical Multiple Units, denoted EMUs in what follows, until now in most cases one-stage or two-stage spur gear transmissions have been used to transmit the drive power from an electric drive motor to the wheelset shaft and the drive wheels. Among other things EMUs are used as Metro, subways or underground railways in public transport systems. In this context a Metro is a crossing-free system which is independent of other traffic systems and motorized individual traffic. Metro vehicles are almost exclusively electrically driven. A Metro vehicle designed as a locomotive has at least one driven axle coupled to an electric drive motor, which is also known as a driving wheelset. Furthermore, such a locomotive can also comprise one or more idler wheelsets not coupled to a drive motor.
Owing to differences in the maximum operating speeds, which for Metro vehicles amount as a rule to between 60 km/h and 130 km/h, and varying motor designs, the transmission ratios usually vary conventionally between 6 and 12. However, power-trains of such rail vehicles used in practice usually have no speed-change transmissions or gearshift transmissions, i.e. the power-train has only a single, non-variable transmission ratio. Until now this had led to the need that depending on the transmission ratio required, which is chosen as a function of the maximum operating speed envisaged, a transmission is chosen from a large number of transmission variants with different sizes and transmission ratios, which are in stock or on offer, and built into the rail vehicle. Thus, the manufacturers of such rail vehicle transmissions offer transmissions variants of different sizes, so that the possibility of using similar components for the different transmission sizes is extremely limited. This increases the manufacturing and warehousing costs, both for new transmissions and also for replacement parts.
The necessary speed adaptations of the rail vehicle and the rotational direction reversal for reversing the travel direction are carried out by rotational speed regulation and by selecting the desired rotational direction of the electric drive motor. This, however, entails high operating costs because the electric drive motor, and where applicable an inverter, are usually not operated in the optimum efficiency range so that more energy is consumed. Since in contrast to internal combustion engines electric drive motors have two equivalent rotational directions, there is no need to provide a reversing transmission when an electric drive motor is used.
DE 102011011867A1 discloses a transmission for the power-train of a rail vehicle, in particular a Metro vehicle, in which the transmission comprises two transmission stages connected one behind the other. For this, the transmission has an input shaft, an intermediate shaft and a drive output shaft. In this case the drive output shaft of the transmission forms a wheelset shaft of the rail vehicle, on which the two wheel disks of drive-wheels of the rail vehicle are mounted in a rotationally fixed manner. For that reason such a transmission is also known as a wheelset transmission. This transmission is intended to cover a wide range of transmission ratios in order thereby to reduce the above-described, disadvantageous diversity of variants. By virtue of design modifications the overall transmission ratio range can be changed further.