Technical Field This invention relates to a drive arrangement for a rail vehicle wheel, comprising a drive tube arranged around a shaft for the wheel and a drive disc at the end of the drive tube, drive couplings containing rubber being arranged - without metallic connection - to transmit torque between the drive disc and the wheel. Background of the Invention

In some recent drive arrangements for certain rail vehicles, such as trams and the like, the torque from the motor is not transmitted to a wheel shaft but instead directly to the wheel itself by an arrangement as described above.

The problem underlying the invention is to design an arrangement for flexibly transmitting the torque from the drive disc to the wheel without undue decreasing the strength of the wheel. As angular deviations between the drive tube and the wheel shaft may occur, it is further desirable to design the arrangement so as to allow such deviations.

The Invention This is according to the invention attained in that the wheel is provided with a number of bores, which are substantially filled by the drive couplings, each drive coupling having a central metal part for connection to the drive disc, rubber working under compressive and tensile stresses, and stabilizing and reinforcing plates.

The drive couplings are accordingly built into and pre-mounted in the wheel.

In order to allow the above mentioned angular devia¬ tions, the rubber does not completely. fill the space affor- ded to it in the bore in the wheel and the plates, which are arcuate, are interrupted in the areas, where the rubber

does not completely fill the space afforded to it, the result being a greater stiffness of the drive coupling in the circumferential direction, i e the drive direction, than the radial direction of the wheel. For the connection between the drive disc and each drive coupling in the wheel each drive coupling has a cen¬ tral coupling sleeve, which may be connected to the drive disc by means of a screw.

Brief Description of the Drawing The invention will be described in further detail be¬ low under reference to the accompanying drawing, in which Fig 1 is a side view of a part of a rail vehicle wheel in¬ corporating the invention, Fig 2 is a sectional view along the line II-II in Fig 1 and Fig 3 is a sectional view along the line III-III in Fig 1.

Detailed Description of a Preferred Embodiment In the drawing a rail vehicle wheel 1 is depicted as a solid wheel for the sake of simplicity. In reality, it may in its circumferential portion in the region towards its tread 2 and flange 3 be provided with internal rubber elements for sound dampening or springing. The wheel 1 is attached to a shaft (not shown) at its center.

The wheel 1 is arranged to be rotationally driven by means of a drive arrangement, of which only a drive disc 4 is shown in Fig 2 and 3; for the sake of clarity it is not illustrated in Fig 1.

The drive arrangement may further comprise a drive tube, rotationally driven by an electric motor and arranged around the wheel shaft with such play that certain mutual rotational and angular movements are permitted, as will be explained in some detail below. The drive disc 4 is arranged at the end of the drive tube, preferably inter- grally therewith as is indicated in Fig 2.

Drive couplings 5, in the shown case six drive couplings, are arranged, preferably in a precompressed

state, in cup-shaped bores 6 in the wheel 1. A security against disengagement of the drive couplings 5 from their bores 6 is provided by screws 7 and washers 7' between the drive couplings. The drive couplings 5 are equiangularly arranged in a ring around the wheel shaft.

Each drive coupling 5 comprises a central coupling sleeve 8, rubber 9 and stabilizing and reinforcing arcuate plates 10, vulcanized into - and for the outermost plate on - the rubber 9. In the shown embodiment the innermost plate 10 is a full circle, whereas the others are sectors.

The coupling sleeve 8 may be cup-shaped as shown, its open end being arranged to fit together with a circular flange or the like on the drive disc 4 and its closed end being provided with a hole for a screw 11 for the attach- ment of the drive coupling 5 to the drive disc 4. The screw 11 is accessible through an opening 12 in the wheel 1.

The wheel 1 is first provided with the drive couplings 5, possibly held in position by the washers 7' . The drive arrangement is then connected to the wheel 1 in that the drive disc 4 is fastened to the drive couplings 5 by means of the screws 11.

It would of course be possible as a modification to allow the screw to pass through an opening in the drive disc 4 and into a threaded hole in the coupling sleeve 8. As appears from Fig 1 and also Figs 2 and 3, the rubber 9 preferably does not completely fill up the cup- shaped bore 6 in the wheel 1 and most plates 10 are not full circles but arcuate sectors. The interruptions of the rubber 9 and the plates 10 are in the radial direction of the wheel 1, which means that more movements are allowed in this direction than the circumferential direction, which is the drive direction.

One reason for allowing movements in the radial direction is that the drive arrangement with the drive disc 4 and accordingly the coupling sleeve 8 may move angularly

in relation to the wheel 1, as depicted in Fig 1 by dash- dotted lines. In the drive direction, however, the coupling has to be considerably stiffer.

The drive disc 4 need not be a full disc but may equally well be separate ears connected to the drive tube.