Abstract:
A dual-vehicle turntable includes a subframe that incorporates a central pivot, a circular track and a rail cam; a generally circular carriage pivotably couplable to the central pivot and having a plurality of rollers angularly spaced around the periphery thereof that ride on the circular track; and a pair of linearly movable platforms mounted on the carriage, each of the platforms supporting a single vehicle and having a cam follower that tracks the rail cam. When the platforms are aligned with the opening of a garage, they are in a maximum spaced-apart relationship. However, when the carriage rotates, the platforms move towards each other, motivated by the action of the cam followers on the rail cam, thereby decreasing inter-vehicle distance and the lateral space required for the rotation of the vehicles. The platforms return to their original spacing as the carriage completes 180 degrees of rotation.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to vehicle turntables useful for rotating motor vehicles about a pivot point so that they may be driven in a direction opposite that which they were driven onto the turntable. More particularly, the invention relates to a novel two vehicle, garage-installable turntable having a pair of linearly movable platforms which decrease the inter-vehicle distance during rotation, thereby permitting its use in a garage of reduced size. 
   2. Description of the Prior Art 
   Although it is nearly always safer and more convenient to drive a vehicle forward than to drive it in reverse looking over one&#39;s shoulder, in many instances, this is not possible. As land becomes more expensive in cities and heavily populated urban areas, driveways sufficiently wide for a vehicle to make an unbroken U-turn, so that it may drive in a forward direction into the street, are becoming increasingly scarce. It is also well known that, as individuals age, their spatial judgement degrades. This problem is compounded by the inability of many older adults to fully turn their heads. Thus, backing out of a garage is potentially hazardous for the vehicle, the garage and any bystanders. Although it would be highly advantageous to be able to drive forward out of a garage and into the adjacent street, this would require either a garage having front and rear doors (not even an option for garages in most residential areas) or backing into the garage (even more dangerous than backing out of the garage). Still another alternative would be to rotate the vehicle 180 degrees on a turntable while it is in the garage, so that it may driven out in a forward direction. 
   Motor vehicle turntables are nearly as old as the automobile. One of the earliest vehicle turntables, fabricated entirely of metal, and adapted for use in warehouses, garages, factories and similar facilities, is disclosed in U.S. Pat. No. 922,643 to H. M. Verplanck. A geared vehicle turntable for use in small private garages is disclosed in U.S. Pat. No. 1,379,239 to John Barwicki. A vehicle turntable, which functions as an anti-theft device by locking a vehicle in a garage in a transverse position, is disclosed in U.S. Pat. No. 1,661,123 to L. B. Kocsis. A vehicle turntable which uses dynamometer-type rollers to rotate the turntable using power supplied via the wheels of a vehicle, is disclosed in U.S. Pat. No. 1,881,033 to George A. Smith. A gear-driven vehicle turntable which rides on large ball bearings trapped between circular grooves in the turntable and the mounting base is disclosed in U.S. Pat. No. 3,566,798 to Herbert G. Peitzman. A vehicle turntable operated by the weight distribution of the vehicle is disclosed in U.S. Pat. No. 4,562,774 to Alexander Dehring. A turntable equipped with position detectors for small, medium and large automobiles is disclosed in U.S. Pat. No. 4,172,422 to Peter B. McBride. A vehicle turntable employing an automobile-mounted transmitter and a turntable-mounted receiver, and which can only be operated when the transmitter and receiver are vertically aligned, is disclosed in U.S. Pat. No. 4,608,929 to Kap Y. Park. A portable, low-profile vehicle turntable for placement on a driveway is disclosed in U.S. Pat. No. 4,716,837 to Alfred E. Valencia. A vehicle fluid-floatable turntable, that tips about a central axis to inhibit turning while loading, is disclosed in U.S. Pat. No. 4,750,428 to Charles A. Hyte, et al. A vehicle turntable, installable within a cylindrical pit in a driveway and having a friction chain drive system, is disclosed in U.S. Pat. No. 5,086,704 to Wieland R. Mueller, et al. A vehicle turntable mounted atop a lift is disclosed in U.S. Pat. No. 5,538,357 to Wallace E. Boswell. A vehicle turntable, adapted for installation in a garage and having a removable manhole cover in the rotating surface of the platform for maintenance of the components below the platform, is disclosed in U.S. Pat. No. 5,755,160 to Charles N. Blufordcraving. A vehicle turntable, that can be assembled without any welding of components, is disclosed in U.S. Pat. No. 6,382,106 B1 to Elijah Knight. 
   Although, as can be seen from the cited prior art, there are many examples of turntables which are designed to permit the repositioning of a vehicle on a driveway, these prior turntables require extensive installation in the driveway itself, where they are subjected to the elements, the weather, as well as trespassers and vandals. However, mounting a turntable in the driveway solves only half the problem, as one must still back up the vehicle out of the garage and onto the turntable. 
   Although a vehicle turntable installed within a garage would appear to be most advantageous, most garages in this country typically house vehicles in pairs. Thus, any vehicle turntable installed within a garage would have to be designed to rotate a pair of vehicles simultaneously, as there would be insufficient space to rotate a single vehicle at a time if two vehicles in the garage are positioned several feet apart. As there needs to be at least three feet of space between vehicles parked side-by-side in a garage to prevent doors from hitting the adjacent vehicle and to provide convenient access to the interior of the vehicle, such a vehicle turntable would require a garage that is much larger than a standard double-car garage. 
   What is needed is a vehicle turntable, adapted for installation in a garage, that reduces the diameter of rotation for a pair of vehicles so that the garage which houses the turntable may be reduced in size. 
   SUMMARY OF THE INVENTION 
   A dual vehicle turntable, adapted for installation in a double garage, incorporates a pair of linearly movable platforms which decrease inter-vehicle distance during rotation, thereby permitting its use in a garage of reduced size, having a pair of parallel entrance/exit paths, one for each vehicle, and includes a generally circular main frame rotatable about a central axis. The main frame is supported by a central bearing and by a plurality of rollers that are attached to the outer periphery of the main frame, generally equi-angularly spaced around the central axis, rotatable about axes which pass through the central axis, and ride on a circular track having as its center, the central axis. A pair of generally rectangular platforms are mounted on the main frame, such that they move in opposition to one another, and are always equidistant from the central axis. A plurality of rollers are used to minimize friction of movement between the platforms and the main frame. A rail formed in a loop, with a generally circular main pattern concentric with the central axis, and having two lobes 180 degrees apart, functions as a cam. Each platform is equipped with a cam follower that tracks the rail cam. The lobes of the rail cam are oriented so that when the rectangular platforms are aligned with the pair of parallel entrance/exit paths, each platform is positioned a maximum distance from the central axis. As the main frame is rotated about the central axis, each of the platforms tracks initially moves toward the central axis as the cam follower tracks the rail cam. A minimum distance from the central axis is maintained until the main frame begins to approach the 180 degree rotation mark, at which time, the rectangular platforms, once again, move apart from one another. The rectangular platforms move with respect to one another much like the pistons in a horizontally-opposed “boxer-type” internal combustion engine. That is to say that whenever the rectangular platforms move, they both move at the same time, but in opposite directions. The moveable rectangular platforms act to move a pair of vehicles parked on the turntable closer together as the turntable rotates, thereby permitting the vehicles to be rotated in less space, which permits the construction of a garage of smaller size that would be necessary if the vehicles retained their spacing as the turntable rotates. Both the main frame and the rectangular platforms are covered with laminar plates, which provide a level surface onto which a pair of vehicles may be driven. For a preferred embodiment of the invention, the turntable is built within a recess so that the top surface of the turntable is even with the floor of the garage. The turntable is preferably rotated with a remotely controlled electric motor that is coupled to the main frame with belts, gears, chain and sprockets, or other similar means. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top plan view of the sub frame; 
       FIG. 2  is a top plan view of the carriage; 
       FIG. 3  is a top plan view of a moveable platform; 
       FIG. 4  is a cross-sectional view of the central pivot plate and angle beams of the moveable platform, taken through section line  4 - 4  of  FIG. 2 ; 
       FIG. 5  is an enlarged top plan view of a cam follower and pivot assembly; 
       FIG. 6  is a partial cross-sectional view of of the cam follower and pivot assembly, taken through section line  6 - 6  of  FIG. 5 ; 
       FIG. 7  is an enlarged bottom plan view of a moveable platform; 
       FIG. 8  is a top plan view of the carriage having a pair of moveable platforms installed thereon, all of which is rotatably mounted atop the subframe; 
       FIG. 9  is a top plan view of flange bearing used to couple the carriage to the subframe; 
       FIG. 10  is a side elevational view of the flange bearing of  FIG. 9 ; 
       FIG. 11  is a top plan view of the assembly of  FIG. 8  after it has been partially covered with metal decking plates; 
       FIG. 12  is a top plan view of the assembly of  FIG. 11  after it has been rotated 90 degrees; 
       FIG. 13  is a top plan view of the assembly of  FIG. 12  at the same rotational position, but with another metal decking plae installed; and 
       FIG. 14  is a top plan view of the assembly of  FIG. 13  at the same rotational position, but with a final central metal decking plate installed thereon. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The dual vehicle turntable of the present invention is designed for installation in a double garage. For new construction, it may be installed within a generally circular recessin the garage floor. However, as its total height around the circumferential edges is only about 100 milimeters (4 inches), it may also be installed in relief on the garage floor itself, so that both vehicles will climb up stationary ramps (not shown) installed adjacent the circumferentail edge of the turntable. For small and intermediate size vehicles, the diameter of the turntable is about 22 feet. For larger vehicles and full-size pickup trucks, the diameter is about 24 feet. The invention and its method of manufacture of a 22-foot-diameter turntable will now be described in detail with reference to the attached drawing  FIGS. 1 through 10 . Fabrication of a 24-foot-diameter turntable is similar, with the structural components being strengthened commensurate with the expected increased load. Although an attempt has been made to ensure that the drawings are approximately to scale, it should be understood that they are meant to be merely illustrative. 
   Referring now to  FIG. 1 , a generally circular subframe  100  is fabricated from outer and inner concentric rings  101  and  102 , respectively. A currently Each ring  101  or  102  is made by rolling a length of 3 inch×¾″ steel stock on its edge and preferably welding the ends together. The concentric rings  101  and  102  are interconnected by sixteen radial spokes  103 A- 103 P, each of which is fabricated from 2 inch×¼ inch or 1-½ inch×¼ inch steel stock. Each of the sixteen spokes  103 , generally, is welded or bolted to each of the concentric rings  101  and  102  and to a 12-inch diameter ½ inch thick central collector plate  104 . A dual-lobe rail cam  105  fabricated from flat stock 1-½ inches in height and ¾ inch thick is welded to each of the spokes inside the inner ring  102 . For a preferred embodiment of the invention, the rail cam  105  is both bilaterally and quadrilaterally symmetrical about perpendicularly intersecting vertical planes, one plane passing through the apex of each lobe  106 -A and  106 -B, the other passing through the center of the collector plate  104 . It will be noted that the collector plate  104  is equipped with four bolt holes  107 . A flange bearing, shown in  FIGS. 9 and 10 , will be bolted to the collector plate  104  and will provide a central pivot axis. 
   Referring now to  FIG. 2 , a generally circular carriage  200  is fabricated with the following components: a circular hoop  201  is formed by rolling 3 inch×3 inch×angle stock having a wall thickness of ⅜ inch into a circular shape and welding the ends together. Alternatively, the circular hoop  201  may be formed by rolling one 3 inch×⅜ inch stock piece on its edge and rolling another 3 inch×⅜ inch stock piece to form a cylindrical band and then welding the two pieces together to form a hoop of L-shaped cross section. Two identical 2 inch×2 inch square tube beams  202  having a wall thickness of ¼ inch are welded at each end to the circular hoop  201  provide parallel track mounts. A pair of 1-½ inch×1-½ inch angle stock pieces  203 , having a wall thickness of ⅜ inch, are welded to each of the square tube beams  202  in an └, rather than a ┌, configuration. The angle stock pieces  203  provide the tracks for the moveable platforms which will be subsequently installed. A pair of 2 inch×2 inch central angle beams  204 , having a wall thickness of ⅜ inch, are perpendicular to the square tube beams  202 , and extend from one side of the circular hoop  201  to the other. It will be noted that the square tube beams  202  are continuous, while the central angle beams  204  are discontinuous, having an inner portion  204 -A and outer portions  204 -B. They are mounted back-to-back, with the flat portions on top and facing away from one another, as shown in  FIG. 4 . An 8 inch×8 inch×½ inch thick central pivot plate  205  is welded to both central angle beams  204 -A and  204 -B, with its upper surface level with the upper surfaces of the flat portions of the central angle beams  204 -A and  204 -B. A pair of lateral angle beams  206 , fabricated from the same material as the central angle beams ( 204 , generally), are welded to the circular hoop  201  at both ends thereof. It will be noted that the lateral angle beams  206  are parallel to the central angle beams  204 , and attach to the circular hoop  201  near the attachment points of the square tube beams  202 . They are installed with the flat portions on top and facing one another. A pair of 2 inch×2 inch square tube bracing beams  207 , having a wall thickness of 3/16 inch interconnect the circular hoop  201  and the lateral angle eams  206 . Ladder structures  208 , also fabricated entirely from 2 inch×2 inch, 3/16 inch wall square tubing interconnect the circular hoop  201  and the square tube beams  202 . The ladder structures  208  are positioned where the wheels of a vehicle nearest the center of the garage are expected to pass when the vehicles are driven onto and off the turntable. Additional square tube supports  209  handle the load from the other pair of wheels. Eight, 2-½ diameter, flanged ball-bearing roller assemblies  210  are bolted between the vertical portion of the circular hoop  201  and a support bracket  211  or  212 . For a preferred embodiment of the invention, these flanged ball-bearing roller assemblies  210  are procured from Osborn International, which calls them Flanged Load Runners®, with a part number FLR-2 ½. These roller assemblies  210  ride on the outer concentric ring  101  of the subframe  100  shown in  FIG. 1 . Two non-flanged ball-bearing roller assemblies  213 , which are bolted between a square tube beam  202  and a support bracket  213 . These two roller assemblies  213 , which ride on the inner concentric ring  102  of the subframe  100 , are also procured from Osborn Internation, which calls them Plain Load Runners®, with a part number PLRY-2 ½. 
   Referring now to  FIG. 3 , a moveable platform  300  is fabricated from a pair of ladder members  302 , each of which is fabricated entirely from 2 inch×2 inch square tubing having a wall thickness of 3/16 inch. The ladder members  302  are interconnected by a pair of square tube interconnects  304  made from 2 inch×2 inch square tubing having a wall thickness of ¼ inch. A cam follower and pivot assembly  305  is bolted to the moveable platform  300  between the square tube interconnects  304 . A pair of angle brakets (not shown) bridge the gap between the two square tue interconnects  304 , and provide a mounting base for the cam follower and pivot assembly  305 . Each end of a ladder member  302  is welded to a 2 inch×⅝ inch reinforcement bar  306 , which is, in turn, welded to a 3 inch×2 inch angle beam  301 , which has a wall thickness of ¼ inch. It will be noted that the wide portion of the angle beam  301  is horizontal and the narrow portion thereof faces down. 
   Referring now to  FIG. 4 , this cross-sectional view shows a solid cylindrical steel shaft  401  that has been welded to the lower surface of the central pivot plate  205 . It will be noted that opposite sides of the central pivot plate  205  are welded to central angle beams  204 -A and  204 -B. 
   Referring now to  FIG. 5 , the top of the the cam follower and pivot assembly  305  is shown in an enlarged view. The cam follower and pivot assembly  305  comprises an upper ½ inch thick plate  501  with six holes  502  therein, which permit the cam follower and pivot assembly  305  to be bolted to a moveable platform  300 . A cylindrical bearing housing  503  is welded into the center of the upper plate  501  with a circular weldment  504 . 
   Referring now to  FIG. 6 , this partial cross-sectional view of the cam follower and pivot assembly  305  shows a pair of flanged cam follower ball-bearing roller assemblies  601 , which for a preferred embodiment of the invention, are Osborn part numbers FLR 2 ½-1. Although not a part of the cam follower and pivot assembly  305 , the rail cam  105  is also shown in cross-sectional format. Each of the flanged cam follower ball-bearing roller assemblies  601  has a threaded shaft  602  that is anchored in a steel plate  603  that is rigidly attached to a steel shaft  604  that rides in a ball bearing assembly  605  that is installed within the bearing housing  503  that is welded to the upper plate  501 . The ball bearing assembly  605  permits the steel plate  603  to rotate so that a plane passing through the axes of the roller assemblies  601  is always about perpendicular to the vertical surfaces of the rail cam  105 . It will be noted that the rail cam  105  is welded to the radial spokes  103  of the subframe  100  with weldments  606 . 
   Referring now to  FIG. 7 , a moveable platform  300  has been turned upside down. The angle brackets  303 , to which the cam follower and pivot assembly  305  bolts, are visible in this view, as are eight 1-½ inch flanged ball-bearing roller assemblies  701  (Osborn part number FLR-1 ½) that are bolted through an angle beam  301  and a reinforcement bar  306 . When the moveable platform  300  is installed on the carriage  200 , the roller assemblies  701  ride on the upper surface of the horizontal portion of an angle stock pieces  203 . Two moveable platforms  300  are used for each carriage  200 . 
   Referring now to  FIG. 8 , two moveable platforms  300  have been installed on the carriage  200 , and the carriage  200  has been installed on the subframe  100 . The left movable platform will be identified as  300 -A, while the right movable platform will be identified as  300 -B. It will be noted that each cam follower and pivot assembly  305  has been positioned so that the roller assemblies  601  straddle the rail cam  105 . It will also be noted that the eight flanged ball-bearing roller assemblies  210  are positioned above the outer concentric ring  101  and the two non-flanged ball-bearing roller assemblies  213  are positioned above the inner concentric ring  102 . 
   Referring now to  FIGS. 9 and 10 , a double-row tapered roller flange bearing  900  is shown. For a preferred embodiment of the invention, this flange bearing  900  is Dodge® part number 023103, procured from the Rockwell Automation Company. The flange bearing  900  bolts to the central collector plate  104  of the subframe  100  through bolt holes  901  in in the mounting ears  902 . The flange bearing  900  has a stationary outer portion  903 , of which the mounting ears  902  are a part. It also has a rotatable inner part  904  with a cylindrical aperture  905 . The cylindrical steel shaft  401  (see  FIG. 4 ) fits into the cylindrical aperture  905  of the flange bearing  900 , which handles both vertical thrust loads and a share of the side loads of the circular carriage  200 , as it rotates about the subframe  100 . A Zerk grease fitting  906  facilitates lubrication of the flange bearing  900 . 
   Referring now to  FIG. 11 , the assembly of  FIG. 8  has been partially covered with sheet metal decking. Panels  1101 -A,  1101 -B,  1102 -A and  1102 -B are affixed to the carriage with removable screws (now shown), while panel  1103 -B is affixed to the right movable platform  300 -B, also with removable screws. Another panel  1103 -A, similar to similar panel  1103 -B, will be subequently affixed to the left movable platform  300 -A. The small, triangularly-shaped panels  1104 -A and  1104 -B are pivotably attached to the carriage  200  at points  1105  and  1106 , respectively. As the movable platforms  300 -A and  300 -B move toward the center of the carriage  200 , each of the small panels  1104 -A or  1104 -B is rotated by a series-connected cable and spring (not shown) that couple the small panel  1104 -A or  1104 -B to the nearest movable platform  300 , so that they cover an opening that results from the trimmed corners on panels  1103 -A and  1103 -B. On the 24-foot-diameter turntable, the small panels  1104 -A and  1104 -B are not necessary, as panels  1103 -A and  1103 -B may be fully rectangular. 
   Referring now to  FIG. 12 , the carriage  200  has been rotated, with the subframe  100  remaining stationary. As the carriage  200  has rotated, the cam follower and pivot assembly  305  has tracked the rail cam  105 , resulting in movement of the movable platform  300  toward the center of the carriage  200 . 
   For this particular embodiment of the invention, each movable platform moves a total of 18 inches toward the center. Thus, two vehicles resting on the two platforms will be 36 inches closer together within about 30 degrees of carriage rotation. It will be noted that each of the triangularly-shaped panels  1104 -A and  1104 -B have rotated to fill the gaps in the outer corners of panels  1103 -A (not yet shown) and  1103 -B. 
   Referring now to  FIG. 13 , panel  1103 -A has been installed on the left movable platform  300 -A, which is now positioned above the right movable platform  300 -A. When 180 degrees of rotation is complete, the movable platforms  300  exchange places, but will return to the original spaced-apart relationship of  FIG. 11 . It will be noted that panel  1103 -A has slid beneath panel  1103 -B. To avoid a collision of the two panels, small ramps are installed on the carriage beneath the center-most edge of panel  1103 -B so that it will curl slightly upward, thereby permitting panel  1103 -A to travel beneath it. 
   Referring now to  FIG. 14 , a central panel  1401 , which bridges the movable platforms  300  and the panels ( 1103 -A and  1103 -B), has been anchored at its ends to the carriage  200  with screws (not shown). The central panel  1401  covers the gap between panels  1103 -A and  1103 -B when platforms  300 -A and  300 -B are in a maximum spaced-apart relationship. 
   For a preferred embodiment of the invention, the turntable is fabricated so that the center is about two inches higher in elevation than the edges, so that water will drain from the upper surfaces of the sheet metal decking panels to the edges of the turntable. 
   Although only a single embodiment of the invention has been heretofore described, it will be obvious to those having ordinary skill in the art that changes and modifications may be made thereto without departing from the scope and the spirit of the invention as hereinafter claimed.