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You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD OF THE INVENTION 
     The invention relates to an installation for parking motor vehicles in a space-saving manner in parking spaces arranged one above the other, with a lifting tower rotatable about a vertical axis for transporting the motor vehicles to the individual parking spaces, a horizontal transport device and a turning device for the lifting tower. 
     DESCRIPTION OF THE RELATED ART 
     Parking garages are known, in which vehicles go to the parking spaces by way of ramps and roadways. Also known are multi-level systems having parking spaces arranged on a plurality of storeys and with at least one vertically displaceable inter-storey conveyor for transporting the motor vehicle from one storey to another. In this system, the individual motor vehicles can be set down on pallets. Transport installations are also known in which the motor vehicles can be transported horizontally. 
     DE-B 38 30 136 discloses a parking building for motor vehicles having a central elevator. The elevator has a rotatable tower provided with a rotary support structure. The rotary support structure is part of the tower. Maneuvering devices are also provided for displacing the vehicles horizontally. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to improve on installations of the kind set forth above, in such a way that the surface area requirement of the parking building can be kept small with a maximum number of parking spaces. The object of the invention is attained in that the turning device is formed by a turntable which is separate from a lifting tower, the lifting tower being horizontally displaceable on the turntable. 
     In this case, the turntable may be arranged so that it is stationary or it may be displaceable by its own traveling chassis arrangement, for example, a shelf operating assembly. It is preferably provided that a lifting fork is displaceable on the lifting tower. 
     In order to improve the stability of the lifting device, a support roller is advantageously provided at an end of the chassis arrangement remote from the lifting tower. In order to facilitate unloading of the motor vehicles in the respective lowermost parking spaces, it is advantageously provided that the lowermost parking spaces have a base whose height corresponds to the height of the turning device. 
     A further embodiment of the invention provides that the lifting tower is telescopically extendable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention are described hereinafter with reference to the Figures of the drawings. 
     FIG. 1 is a diagrammatic elevational view of an installation according to the invention. 
     FIG. 2 shows an elevational view of the lifting device when delivering a motor vehicle to a parking space. 
     FIG. 3 shows a plan view of the installation. 
     FIG. 4 is a diagrammatic view showing the arrangement of the parking spaces. 
     FIGS. 5 through 11 show plan and elevational views of the various stages in vehicle-transfer and discharge, and 
     FIGS. 12a-c are side views of parking spaces arranged in mutually superposed relationship. Illustrating various support configurations for the motor vehicles. 
     FIG. 13 is a diagrammic view of a second embodiment of an installation according to the invention. 
     FIGS. 14-17 are schematic illustrations of horizontal displacement drives. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The installation according to the invention comprises at least two vertical rows  1  of parking spaces  2  arranged in mutually superposed relationship and a lifting device  3 . The embodiment shown in FIG. 3 has three rows  1  of parking spaces  2  arranged in vertically mutually superposed relationship. It would however also be readily possible to provide a fourth row  1 , in which case a region, (door opening)  14  is left free only at the first floor level to permit the motor vehicles  5  to go to the lifting device  3 . 
     The lifting device  3  has a lifting tower (mast)  6  on which a lifting fork  7  is vertically displaceable. The lifting tower  6  is arranged on a turntable  8 . The turntable  8  is provided with a rotary track ring and can be turned through  360 °. 
     The lifting tower  6  has a traveling chassis arrangement  9  which is provided at its free end with a support roller  10 . The lifting device  3  or the traveling chassis arrangement  9  thereof is mechanically connected to the turntable  8 . Horizontal displacement of the lifting device via a horizontal transport device is advantageously effected by way of a spindle drive  20   a  (FIG. 14) or a toothed rack drive  20   b (FIG.  15 ). It is however also possible to use a hydraulic drive  20   c  (FIG. 16) or pneumatic drive  20   d (FIG. 17) for the horizontal transport device. The drive for the spindle drive or the toothed rack drive is afforded by way of electric motors, preferably servomotors. 
     Provided below the parking spaces  2  of the lowermost row  1  is a base  11 , the height of which corresponds to the height of the turntable  8 , so that the traveling chassis arrangement  9  can be moved from the receiving position for the motor vehicle  5 , as shown in FIG. 1, into the delivery position shown in FIG. 2 at the parking space  2 . 
     The feed of motor vehicles  5  is effected as described hereinafter. The motor vehicle  5  drives onto two drive-on channels  12  or a drive-on pallet which rests on the lifting fork  7  of the lifting device  3 . The turntable  8  with the lifting mast  6  is then turned until the motor vehicle  5  is oriented in the desired direction. Thereupon the motor vehicle  5  is raised by means of the lifting fork  7  and moved to the desired parking space  2 . 
     When the desired height is reached, the lifting mast  6  with the traveling chassis arrangement  9  is moved into the position shown in FIGS. 10 and 11. The drive-on channels  12  are put down onto shelf profile members  13  and thus the motor vehicle  5  is stored at the parking space. It is also possible to provide pallets instead of the drive-on channels  12 . In principle it would also be possible for the motor vehicle  5  firstly to be raised to the desired storey and then for the lifting device  3  to be turned. 
     The lifting device  3  moves back again into its central receiving position shown in FIGS. 5,  6  and  7  and the lifting fork  7  is oriented with respect to the door opening  14 . 
     The reversed procedure is involved in fetching each motor vehicle  5  from its parking space  2 . Storage of the motor vehicle  5  does not have to be effected by way of drive-on channels  12  or by way of a drive-on pallet. The parking spaces  2  can also be in the form of cantilever-arm shelf assemblies  15 . 
     In this case, the motor vehicle  5  is lifted by channels  16  which are mounted on the lifting fork  7  and which are oriented transversely with respect to the longitudinal axis of the vehicle and on which it rests with its wheels (see FIG. 12 a ). After the desired parking space  2  is reached the motor vehicle is set down with the chassis thereof directly onto the cantilever arms  15 . 
     The installation according to the invention is preferably provided with three or four vertical rows  1  of parking spaces  2  arranged in mutually superposed relationship, as shown in FIG.  3 . It is however also possible for the turntable  8  to be arranged with its drive on its own traveling chassis arrangement so that the lifting device  3  is displaceable, in a similar manner to a high-level shelf in a movable shelf assembly. It is likewise possible, as shown in FIG. 4, to provide more than four rows  1  of parking spaces  2  which can be served by the lifting device. In that case, the rows  1  are arranged substantially in a polygonal array. It is further possible, as shown in FIG. 13, to have a lifting device  21  with a telescopically extendable lifting tower  22  to lift the vehicle  5 .

Summary:
The invention relates to an installation for parking motor vehicles ( 5 ) in a space-saving manner, having a plurality of parking spaces ( 2 ) arranged on top of each other and designed to hold the motor vehicles ( 5 ). The invention provides for a lifting device ( 3 ) for transporting the motor vehicles ( 5 ) to the individual parking spaces ( 2 ), the lifting device being mounted on a turntable ( 8 ). In addition, the lifting device ( 3 ) can be horizontally displaced on the turntable ( 8 ).