Tilting drive arrangement for a converter
BACKGROUND OF THE INVENTION 
     The invention relates to a tilting device for converters having a spur gear wheel fastened to a tilting trunnion and on which wheel at least two pinions, driven by a common motor and connected by a shaft, engage. 
     Tilting drives of this kind have already been known and are called Bogiflex-drives. With these drives each pinion is mounted by means of a car guided on an inner flange of the spur gear wheel and arranged diametrically opposite each other in the horizontal plane extending through the tilting trunnion axis. The cars are held together by a rod linkage and each car is torque-supported against the base by a rod linkage. This known arrangement has the disadvantage that only two pinions can be provided on the spur gear wheel in the described diametrical arrangement, which is insufficient for heavy drives. For heavy drives used for the transmission of large torques, more than two pinions are necessary. Another disadvantage of the diametrical arrangement is that the pinions, the holding means and the rod linkage lie relatively high above the working platform, thus restricting the space. 
     SUMMARY OF THE INVENTION 
     The invention aims at avoiding the described disadvantages and difficulties and has as its object to provide a tilting drive with at least two drive pinions and a torque division which, on the one hand, can be arranged below the working platform if only two pinions are required, thus saving space, and on the other hand, can comprise also more than two pinions for heavy drives. Furthermore, the invention aims at providing a compact construction that is operationally safe and is not liable to disturbances. 
     The object is achieved in that the pinions are mounted in a carrying drive casing overmounted on the tilting trunnion in a position outside the horizontal plane extending through the tilting axis of the converter. 
     Further advantages achieved in this manner are encasement against influences from the outside (dust, etc.), and the possibility of being able to use a circular lubrication system with oil, instead of a grease lubrication system. 
     According to a preferred embodiment two pinions are oppositely mounted in the drive casing below the horizontal plane extending through the tilting axis, the drive motor being arranged on the base and connected to one pinion, each via a bevel gearing. 
     In this case, the drive motor suitably is connected with one pinion each via at least one torsionally elastic shaft. The tooth plays of each drive chain are thus balanced out, so that both pinions participate equally in the torque transmission. 
     Advantageously, in another embodiment each pinion is driven via a separate reduction gear, each gear being mounted on the gear casing so as to be pivotable about the respective pinion axis. The reduction gears are motion-coupled to each other, for instance via a ball and socket mounting or a toothing and the bevel gears are each drive-connected with the reduction gears via a universal joint propeller shaft. With this arrangement, the tooth plays are balanced out by a movement of the reduction gears relative to the gear casing. 
     According to a further preferred embodiment, two opposed pinions are each arranged below and above the horizontal plane extending through the tilting axis. The pinions, which are arranged one above the other are connected by torsionally elastic shafts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention shall be explained in more detail by way of several embodiments and with reference to the accompanying drawings, wherein: 
     FIGS. 1, 3 and 4 are each schematic side views of separate embodiments of tilting drives having two drive pinions, 
     FIG. 6 illustrates in side view an embodiment of a heavy drive having four drive pinions, and 
     FIGS. 2 and 5 show sections along lines II--II and V--V, respectively, of FIGS. 1 and 4. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A converter 1 is inserted in a carrying ring 2. The carrying ring is connected with tilting trunnions 3, 4, which are mounted in bearings 5, 6, so that the ring is fixed against rotation with respect to the trunnions. The tilting trunnion 3 is elongated beyond the bearing 5. On its end a spur gear wheel 7 is provided so as to be secured against rotation with respect to the trunnion. The spur gear wheel is enclosed in a gear casing 8 which is supported via a torque support 9 on the base 10 and is overmounted on the tilting trunnion 3. 
     Two pinions 11, 12 are mounted in the gear causing 8 symmetrically with respect to the vertical plane 14 extending through the tilting axis 13 of the converter and below the horizontal plane 15, which also extends through the tilting axis 13, so that they mesh with the spur gear wheel 7. 
     The two pinions 11, 12 are commonly driven by a single drive motor 16, which preferably is a rotary current motor. The drive motor 16 is arranged on the base 10 and, via two couplings 17, 18 and two bevel gears 19, 20, drives reduction gears 21, 22, each placed before one pinion. Between each of the bevel gears 19, 20 and each of the reduction gear 21, 22, torsionally elastic shafts 23, 24 are provided. The torsion elasticity of each shaft is greater than the sum of the tooth plays of the drive chain starting from the motor 16 and leading to the spur gear wheel 7. 
     As can be seen from FIG. 1, the reduction gears each lie below a working platform denoted by 25, so that the latter will not be restricted in space by any drive elements, except for the gear casing 8. According to FIG. 3, the drive motor is arranged on a console 26 fastened to the gear casing 8. Driving is effected from the drive motor via a shaft 27 to the reduction gear 22&#39; and from there, via a torsionally elastic shaft 28, to the second reduction gear 21&#39;. 
     According to the embodiments illustrated in FIGS. 4 and 5, the reduction gears 21&#34;, 22&#34;, which embodiment otherwise is the same as that shown in FIG. 1, are mounted on the gear casing 8&#39; so as to be pivotable about the axes of the pinions 11, 12 and coupled together by a ball and socket bearing 29, whereby the tooth plays of each drive chain can be balanced out by a reverse rotational movement of the reduction gears 21&#34;, 22&#34;, relative to the gear casing 8. Instead of the ball and socket bearing, another type of coupling of the reduction gears 21&#34; and 22&#34; also be provided, for instance a toothing. No torsionally elastic shaft need be provided between the bevel gears and the reduction gears. In this case simple universal joint propeller shafts will suffice. 
     In FIG. 6 a tilting drive for particularly heavy converters is illustrated in which four pinions 30, 31, 32, 33 are provided, which are arranged symmetrically with respect to the vertical plane 14 and the horizontal plane 15 that extend through the tilting axis. Each pinion is provided with a reduction gear 34 to 37 flanged to the gear casing, the reduction gears 34, 35 and 36, 37, each lying one above the other and being drivable by means of drive motors 38, 39, respectively, fastened to the gear casing 8. Each of the drive motors 38, 39 at first is directly flanged to a reduction gear 34, 36, which in turn is drive-connected, via a torsionally elastic shaft 40 and 41, respectively, to the reduction gear 35 and 37, respectively, arranged thereabove.