Abstract:
A universal shift apparatus and method for a swimming pool cover motor has a rotatable drive shaft and a rope attached to the end of the swimming pool cover. A reel element collects the rope, and a roll-up element collects the swimming pool cover. A gear drive assembly on the rotatable drive shaft drives the reel element in a first rotational direction as the shaft rotates in a first direction and drives the roll-up element in a second rotational direction as the shaft rotates in a second direction. A shift assembly is associated with the gear drive assembly to selectively reverse the first rotational direction of the wind-up reel element and to selectively reverse the second rotational direction of the roll-up element.

Description:
FIELD OF INVENTION 
     The present disclosure relates to swimming pools, and, more particularly, to a universal shift apparatus and method for a swimming pool cover assembly. 
     BACKGROUND 
     Swimming pool covers are often used for keeping the water free of trash, to shield the water from sunlight that could degrade protective chemicals in the water and for other purposes. Automatic pool covers are often preferable over manually-operated covers, because the cover can be easily extended when the pool is not in use and retracted during use. In most cases, a pool cover box is located at one end of the pool to hold the pool cover system. 
     Referring to  FIG. 1A , an abstract view of a typical pool cover system  10  is shown. System  10  includes a motor  12 , a drive shaft  14  extending from motor  12 , a wind-up reel  16  for collecting a rope  18 , a gear box  20 , a swimming pool cover  22  and a roll-up tube  24  on which to wind the cover  22 . Rope  18  extends to a remote pulley system (not shown) and then back to a leading edge of the cover  22 . Reel  16  and a roll-up tube  24  are usually mounted in a free-wheeling fashion on drive shaft  14  to turn independently therefrom. Gear box  20  includes mechanisms to engage either the reel  16  or the roll-up tube  24 , depending on whether the cover  22  is to be extended or retracted. 
     By turning drive shaft  14  in direction A, clockwise relative to motor  12  as shown, shaft  14  engages the gear mechanism in gear box  20  to drive reel  16  in direction A. This action winds rope  18  on reel  16 , thereby causing cover  12  to be extended outward over the pool (not shown). Alternately, by rotating drive shaft  14  in direction B, counter-clockwise relative to motor  12 , roll-up tube  24  is engaged by drive shaft  14  via the mechanism in gear box  40 , so that the pool cover  22  is retracted on tube  24  and removed from above the pool. The pool cover system  10  shown in  FIG. 1A  is referred to as a right-hand system, since the pool cover motor is located on the right side in the pool cover box (not shown). 
     Sometimes the layout of the pool and its surroundings dictate that the pool cover motor be located on the left-hand side of the pool cover box, as shown in  FIG. 1B . The pool cover system  30  shown in  FIG. 1B  is referred to as a left-hand system, since the pool cover motor  32  is situated on the left side of the pool cover box. As in  FIG. 1A , the drive shaft  34 , reel  36 , rope  38 , cover  42  and roll-up tube  44  are substantially identical to the corresponding elements shown in  FIG. 1A . The main distinction is that different mechanisms are needed in gear box  40 , compared to the mechanisms in gear box  20 , in order for reel  36  and roll-up tube  44  to be engaged to rotate in directions opposite to the directions of rotation in the right-hand pool cover system shown in  FIG. 1A . 
     Accordingly, in  FIG. 1B , if the drive shaft  34  rotates in a direction C, counter-clockwise to motor  32 , this action turns reel  16  in direction C to collect the rope  38  on reel  36 . Alternately, if drive shaft  34  rotates in a direction D, clockwise to motor  32 , then cover  42  is retracted onto roll-up tube  44 . 
       FIG. 2A  shows a gear box  20  having a prior art gear mechanism  50  for the right-hand system in  FIG. 1A . A single dog gear  52  is fixedly mounted to roll-up tube  24  (shown in  FIG. 1A ). Another single dog gear  54  is fixedly mounted to reel  16  (shown in  FIG. 1A ). A double dog gear  56  is rotatably mounted on drive shaft  14  to be free-wheeling along shaft  14 . A shear pin  57  is secured into drive shaft  14  to extend orthogonally outward from the drive shaft  14 . The shear pin  57  extends into a slanted slot  58  formed in double dog gear  56 . 
     Accordingly, as drive shaft  14  is rotated in direction A, double dog gear  56  is moved along drive shaft  14  in the direction E, so that double dog gear  56  couples single dog gear  54  to drive reel  16  and collect rope  18 , shown in  FIG. 1A . Alternately, as drive shaft  14  is rotated in direct B, double dog gear  56  is moved along drive shaft  14  in the direction F, engaging single dog gear  52 . This action drives the roll-up tube  24  and collects the pool cover  22 , shown in  FIG. 1A . 
     Similarly,  FIG. 2B  shows gear box  40  having a prior art gear mechanism  60  that drives the left-hand system shown in  FIG. 1B . A single dog gear  62  engages roll-up tube  44 , and a single dog gear  64  engages reel  36 . A double dog gear  66  is mounted to free-wheel on drive shaft  34 . When drive shaft  34  rotates in direction C, double dog gear  66  is forced by shear pin  67  along shaft  34  in direction H. This engages the reel  36  to collect the rope  38 , shown in  FIG. 1B . When drive shaft  14  rotates in direction D, double dog gear  66  is forced by shear pin  67  along shaft  34  in direction G. This engages the roll-up tube  44  to retract cover  42 , as shown in  FIG. 2B . 
     Accordingly, prior art systems involve a swimming pool builder using both right-hand and left-hand motor systems, including different gear boxes, in order to work with various pool layouts and the requirements of customers. Consequently, both right-hand and left-hand types of motor systems must be readily supplied by a pool equipment supplier, adding to the supplier&#39;s inventory demands. Moreover, it is difficult to forecast which type of system will be in greater demand, resulting in over-supply and under-supply of right and left-hand motor systems. Furthermore, complex prior art gear boxes, such as shown in  FIGS. 2A and 2B , are relatively expensive and are maintenance-intensive. 
     A pool cover motor system may also be equipped with a torque limiter separately mounted, so that, in the event the cover or one of its components becomes jammed or stuck, the motor or other parts of the pool cover motor system will not be damaged. Typically, torque limiter apparatus includes some type of device that slips relative to the rotatable shaft in the event that a predetermined torque limit on the device is exceeded. However, adding a torque limiter to the motor system also adds extra cost to the manufacture of the motor system. 
     SUMMARY 
     In one exemplary implementation, a universal shift apparatus and method for a swimming pool cover motor has a rotatable drive shaft and a rope attached to the end of the swimming pool cover. A reel element collects the rope, and a roll-up element collects the swimming pool cover. A gear drive assembly on the rotatable drive shaft drives the reel element in a first rotational direction as the shaft rotates in a first direction and drives the roll-up element in a second rotational direction as the shaft rotates in a second direction. A shift assembly is associated with the gear drive assembly to selectively reverse the first rotational direction of the wind-up reel element and to selectively reverse the second rotational direction of the roll-up element. 
     In another exemplary embodiment, a method is provided for adapting a reel apparatus for a swimming pool cover motor having a rotatable drive shaft and a rope attached to the end of the swimming pool cover. The method comprises collecting the rope on a reel element and collecting the swimming pool cover on a roll-up element. The reel element is driven in a first rotational direction as the shaft rotates in a first direction. The roll-up element is driven in a second rotational direction as the shaft rotates in a second direction. The first rotational direction of the wind-up reel element and the second rotational direction of the roll-up element are reversed using a shift assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned features and other features and advantages of this disclosure will become more apparent and the disclosure will be better understood by reference to the following description of an exemplary implementation taken in conjunction with the accompanying drawings, wherein: 
         FIGS. 1A and 1B  are generalized top views of right-hand and left-hand swimming pool cover motor assemblies; 
         FIGS. 2A and 2B  are schematic representations of prior art gear mechanisms in the pool cover motor assemblies shown in  FIGS. 1A and 1B ; 
         FIG. 3  is a plan partial view of a right-hand pool cover motor assembly, with a shift arm in a first position, in accordance with the present disclosure; 
         FIG. 4  is a plan partial view of the right-hand pool cover motor assembly of  FIG. 3  with the shift arm in a second position, in accordance with the present disclosure; 
         FIG. 5  is a blown-up schematic view of the right-hand pool cover motor assembly shown in  FIGS. 3 and 4 ; 
         FIGS. 6A and 6B  are perspective and plan views of the reel assembly of the pool cover motor assembly shown in  FIGS. 3 and 4 ; 
         FIGS. 7A and 7B  are perspective and plan views of the drive cone assembly of the pool cover motor assembly shown in  FIGS. 3 and 4 ; 
         FIG. 8A  is an exploded perspective view of the torque limiter of the pool cover motor assembly shown in  FIGS. 3 and 4 ; 
         FIG. 8B  is a perspective view of the torque limiter of  FIG. 8A  and reel assembly of the pool cover motor assembly shown in  FIGS. 3 and 4 ; 
         FIG. 9A  is a plan partial view of a left-hand pool cover motor assembly, with a shift arm in a first position, in accordance with the present disclosure; 
         FIG. 9B  is a plan partial view of the left-hand pool cover motor assembly of  FIG. 9A , with the shift arm in a second position, in accordance with the present disclosure; 
         FIG. 10A  is an exploded perspective view of the torque limiter of a left-hand pool cover motor assembly in accordance with the present disclosure; and 
         FIG. 10B  is a perspective view of the torque limiter of  FIG. 10A  and the reel assembly of the left-hand pool cover motor assembly shown in  FIG. 9A . 
     
    
    
     Throughout the drawings, identical reference numbers may designate similar, but not necessarily identical, elements. The examples herein illustrate selected implementations of the disclosure in certain forms, and such exemplification is not to be construed as limiting the scope of the disclosure in any manner. 
     DETAILED DESCRIPTION 
     The present apparatus and method described herein make it possible to have a universal shift or transposer mechanism that can be employed as either a right-hand system or a left-hand system for pool cover motor assemblies. The present apparatus and method uses the same gear mechanism for both right-hand and left-hand systems, only requiring a change in the orientation of one component in the gear mechanism to make the conversion. This simple gear structure eliminates the need to stock separate right-hand and left-hand pool cover motor assemblies, substantially reducing the inventory required for pool cover motor assemblies. 
     In addition, the embodiments of the present invention described herein incorporate a torque limited connected to the above gear mechanism. This arrangement utilizes the torque limiter to function both to limit the torque applied to the pool cover motor assembly and to connect the gear mechanism to the drive shaft of the motor. This structure substantially simplifies having a torque limiter as part of the system and reduces the cost of manufacturing accordingly. 
     Right-hand Pool Cover Motor System 
     Referring now to the drawings, and more particularly to  FIG. 3  illustrates a portion of a right-hand pool cover motor system  70  according to one exemplary implementation. Motor system  70  includes a rope reel unit  72  (also referred to as “reel unit  72 ”) having dual side-by-side reels  74 ,  75  for collecting ropes on spindles  76 ,  77  from each of the two sides of a pool cover (not shown). Reel unit  72  is mounted on a bushing  79  to freely turn on a drive shaft  80  which comes from a pool cover motor (not shown). One side of reel unit  72  comprises a reel disc  78 , for interfacing with the gear mechanism to be discussed later. 
     A drive cone unit  82  is also mounted to freely turn on drive shaft  80  and attached by a roll-up collar  85  to a roll-up tube to the left of drive cone unit  82  (not shown) for collecting a pool cover. Drive cone unit  82  includes a cone piece  84  that is connected to a neck piece  86  and then to a drive cone disc  88 . Drive cone disc  88  interfaces with the gear mechanism  90 , as discussed below. As can be seen the pool cover motor system  70  is a right-hand system because the pool cover motor would be on the right side with the roll-up tube on the left hand side of the system  70 . 
     A gear mechanism  90  is shown between reel disc  78  and drive cone disc  88 . The gear mechanism includes a torque limiter  92  resistively mounted on drive shaft  80  by clamp ring  95 , to be discussed later. A shift base  94  is mounted on torque limiter  92  and a shift arm  96  pivotally mounted on shift base  94 . Reel disc lugs  100  are spaced around the surface  102  of reel disc  78  that faces toward gear mechanism  90 . Likewise drive cone disc  88  includes drive cone disc lugs  104  spaced around the surface  106  of drive cone disc  88  that faces toward gear mechanism  90 . 
     Gear mechanism  90  includes a shift arm  96  (also referred to as “shift member  96 ”) mounted on a pivot mount  98  on shift base  94 . The shift arm  96  pivots at 45 degrees relative to the axis of the drive shaft  80 . The pivot action of shift arm  96  responds to the pull of gravity to fall against the reel disc lugs  100  as the drive shaft  80  rotates in the direction A (clockwise, looking in from the end of shaft  80 ) as shown in  FIG. 3 . This pivot action rotates torque limiter  92  that is fixedly mounted on drive shaft  80 . The rotation of torque limiter  92  places shift arm  96  behind and in contact with reel disc lug  100   a,  thereby driving reel unit  72  also in direction A′. This rotation causes the rope (not shown) to wind up on reel unit  72  by coming in at the bottom of reels  76  and  77 , similar to that shown in  FIG. 1A . 
     Referring now to  FIG. 4 , the same portion of a pool cover motor system  70  is shown with the same components shown and described with respect to  FIG. 3 . However, in  FIG. 4  the drive shaft  80  is shown rotating in the direction B′ (counter-clockwise, looking in from the end of the shaft  80 ). This rotational direction B′ causes torque limiter  92  to rotate in the B′ direction. The pull of gravity causes shift arm  96  to shift behind and in contact with lug  104   a  on cone drive disc  88  thereby causing it to rotate. This rotation of drive disc  88  causes cone drive  82  and roll-up tube (not shown) to rotate in the B direction, thereby collecting the pool cover that comes in at the top of roll-up tube, similar to that shown in  FIG. 1A . 
     The foregoing description shows the simplicity and genius of the gear mechanism  90 . The reel unit  72  and the drive cone unit  82  are separately driven by the shift arm  96 , depending on the direction of rotation of drive shaft  80 . The only moving part is shift arm  96 , which simply pivots one of two directions to make contact with one of the appropriate lugs. The direction of rotation determines whether the reel unit  72  is to be driven to collect the rope, thereby extending the pool cover, or whether the drive cone unit  82  is to be driven to retract the pool cover. 
       FIG. 5  provides an exploded view of the pool cover motor system  70 . Drive cone unit  82  includes a roll-up tube collar  85  that connects to the roll-up tube (not shown). Drive cone unit also includes cone piece  84 , neck piece  86  and drive cone disc  88 , previously discussed. A plastic bushing  81  and a metal bushing  83  attach the drive cone unit  82  to freely turn on drive shaft  80 . Likewise, reel unit  72  is attached to freely turn on drive shaft  80  by a plastic bushing  72  and a metal bushing  73 . 
     The gear mechanism  90  is fixedly secured to drive shaft  80  by torque limiter  92  using the split hubs  91  and  93 . A split ring  97  is mounted on split hubs  91  and  93  and the combination is clamped onto the drive shaft  80  by clamp ring  95 . The torque limiter  92  has a base mount  99  on which the shift base  94  is secured. The shift arm  96  is pivotally secured on the shift base  94 . Various nuts, bolts, washers, pins and screws are shown in  FIG. 5  having obvious functions of connecting the components shown. 
       FIGS. 6A and 6B  show the structure of the reel disc  78  more clearly. Dual reels  74  and  75  are connected together on the same axis. The inner surface  102  of reel disc  78  has reel disc lugs  100  spaced around the periphery of surface  102 . A circular opening  103  extends through the center of reel disc  78  to accept bushings  71  and  73 , shown in  FIG. 5 . Bushing  71  is also shown in place in  FIG. 6B . 
       FIGS. 7A and 7B  show the structure of the drive cone unit  82  more clearly. Roll-up tube collar  85  is connected to cone piece  84 . The drive cone disc  88  includes inner surface  106  with several drive cone disc lugs  104  spaced around the periphery. A circular opening  107  extends through the drive cone unit  82  to accept drive shaft  80 . Holes  109  are disposed in drive cone disc  88  for access purposes. 
       FIG. 8A  shows the torque limiter  92  and gear mechanism  90  in more detail. The torque limiter  92  includes split hubs  91  and  93 , also shown in  FIG. 5 . Only split hub  91  is visible in  FIG. 8A . Hub  91  and  93  may be made of aluminum or other suitable material. A circular opening  120  extends through the center of hubs  91  and  93  to accommodate shaft  80 . Split ring  97  surrounds hubs  91  and  93  and is split to enable the ring  97  to be compressed to secure the torque limiter  92  on shaft  80 . Split ring  97  may be made of nylon or other suitable material to function as a split ring under compression. Outside ring clamp  95  surrounds split ring  97  and may be clamped tightly on ring  97  by a bolt  122  extending through a pinch member  124 . Clamp ring  95  may be made of cast stainless steel or other suitable material. 
     Torque limiter  92  is useful in preventing damage to the pool cover motor and other elements in the system in the event that the pool cover becomes jammed or the system otherwise cannot continue to rotate. In that case, the torque limiter acts as a breaker to prevent system damage. When the torque becomes greater than the clamping pressure of the ring clamp  95 , torque limiter  92  will allow slippage between the hub  91 ,  93  and the split ring  97 . Outside ring claim  95  may be tightened so that torque limiter  92  may withstand any amount of torque desired. Typical thresholds where one might want to begin slippage could be in the range of from 400 inch pounds up to 1100 inch pounds. 
     The torque limiter  92  has a base mount  99  on top of ring clamp  95 . The shift base  94  is secured on base mount  99  by a bolt  126  extending through a hole  127  in base mount  99 , a corresponding hole  129  in shift base  94  and secured by a nut  128 . The shift arm  96  is pivotally secured on the shift base  94  by a bolt  130  extending through a hole (not shown) in pivot mount  98  to connect to a nut (not shown). The shift base  94  is mounted on base mount  99  so that the shift arm  96  pivots at a 45 degree angle relative to the vertical axis of torque limiter  92 . This enables the shift arm  96  to fall with the force of gravity against one of the lugs to drive either the reel unit  72  or the drive cone unit  82 , as described in connection with  FIGS. 3 and 4 . 
       FIG. 8B  shows torque limiter  92  mounted on drive shaft  80 . The shift arm  96  has pivoted to contact one of the reel disc lugs  100   a,  so as to drive reel unit  72  in a counter-clockwise rotation, as described in connection with  FIG. 3 . 
     Left-hand Pool Cover Motor System 
       FIGS. 9A and 9B  partially show a left-hand pool cover motor system  170  according to another embodiment. This system is essentially a mirror image of the right-hand pool cover motor system shown in  FIGS. 3 and 4 . As a result, the reference numbers used for similar element are offset by 100. Motor system  170  includes a rope reel unit  172  having dual side-by-side reels  174 ,  175  for collecting ropes on spindles  176 ,  177  from each of the two sides of a pool cover (not shown). Reel unit  172  is mounted on a bushing  179  to freely turn on a drive shaft  180  which comes from a pool cover motor (not shown). One side of reel  174  comprises a reel disc  178 , for interfacing with the gear mechanism to be discussed later. 
     A drive cone unit  182  is also mounted to freely turn on drive shaft  180  and attached to a roll-up tube (not shown) to the right of drive cone unit  182  for collecting the pool cover. Drive cone unit  182  includes a cone piece  184  that is connected to a neck piece  186  and then to a drive cone disc  188 . Drive cone disc  188  interfaces with the gear mechanism, as discussed below. As can be seen the pool cover motor system  170  is a left-hand system because the pool cover motor is on the left side and the roll-up tube is on the right-hand side of the system. 
     A gear mechanism  190  is shown between reel disc  178  and drive cone disc  188 . The gear mechanism includes a torque limiter  192  resistively mounted on drive shaft  180  by clamp ring  195 , to be discussed more later. A shift base  194  is mounted on torque limiter  192  and a shift arm  196  pivotally mounted on shift base  194 . Reel disc lugs  200  are spaced around the surface  202  of reel disc  178  that faces toward gear mechanism  190 . Likewise drive cone disc  188  includes drive cone disc lugs  204  spaced around the surface  206  of drive cone disc  188  that faces toward gear mechanism  190 . 
     Shift arm  196  is mounted on a pivot mount  198  on shift base  194  so that the shift arm  196  pivots at 45 degrees relative to the axis of the drive shaft  180 . The pivot action of shift arm  196  responds to the pull of gravity to fall against the reel disc lugs  200  as the drive shaft  180  rotates in the direction C′ (counter-clockwise, looking in from the end of shaft  180 ) as shown in  FIG. 9A . This pivot action rotates torque limiter  192  that is fixedly mounted on drive shaft  180 . The rotation of torque limiter  192  places shift arm  196  in front and in contact with reel disc lug  200   a,  thereby driving reel unit  172  also in direction C. This rotation causes the rope (not shown) to wind up on reel unit  172  by coming in at the bottom of reels  176  and  177 , similar to that shown in  FIG. 3 , except that system  170  is a left-hand system. 
     Referring now to  FIG. 9B , the same portion of a pool cover motor system  170  is shown with the same components shown and described with respect to  FIG. 9A . However, in  FIG. 9B , the drive shaft  180  is shown rotating in the direction D′ (clockwise, looking in from the end of the shaft  180 ). This rotational direction D′ causes torque limiter  192  to rotate in the D′ direction. The pull of gravity causes shift arm  196  to shift behind and in contact with lug  204   a  on cone drive disc  188  thereby causing it to rotate. This rotation of drive disc  188  causes cone drive  182  and roll-up tube (not shown) to rotate in the D direction, thereby collecting the pool cover that comes in at the top of roll-up tube, similar to that shown in  FIG. 4 , except that system  170  is a left-hand system. 
     The foregoing description further shows the simplicity and genius of the gear mechanism  90 . The reel unit and the roll-up tube are selectively driven by the shift arm  196 , depending on the direction of rotation of drive shaft  180 . The only moving part is shift arm  196 , which simply pivots one of two directions to make contact with one of the appropriate lugs. The direction of rotation determines whether the reel unit  172  is to be driven to collect the rope, thereby extending the pool cover, or whether the drive cone unit  182  is to be driven to retract the pool cover. 
     Further, the present invention enables the use of a gear mechanism  190  that is the same as the gear mechanism  90 , shown in  FIGS. 3 and 4  except that the shift arm  196  has been rotated by 90 degrees to fall with the pull of gravity in a manner opposite to that described for a right-hand system. 
       FIGS. 10A and 10B  illustrate more clearly the ease in shifting or transposing the gear mechanism of the present embodiments so as to accommodate a left-hand system, rather than a right-hand system.  FIGS. 10A and 10B  show a left-hand system in contrast to the right-hand arrangement shown in  FIGS. 8A and 8B .  FIG. 10A  shows the torque limiter  192  that includes a split hub  191  and a second split hub  193  (not shown) on the opposite side of the torque limiter. A circular opening  220  extends through the center of hubs  191  and  193  to accommodate shaft  180 . Split ring  197  surrounds hubs  191  and  193 , being split to enable the ring  197  to be compressed to secure the torque limiter  192  on shaft  180 . Outside ring clamp  195  surrounds split ring  197  and may be clamped tightly on ring  197  by a bolt  222  extending through a pinch member  224 . 
     The torque limiter  192  has a base mount  199  on top of ring clamp  195 . The shift base  194  is secured on base mount  199  by a bolt  226  extending through a hole  227  in base mount  199  and a corresponding hole  229  in shift base  194  and then secured by a bolt  228 . The shift arm  196  is pivotally secured on the shift base  194  by a bolt  230  extending through a hole in pivot mount  198  to connect to a nut  232 . As shown, the shift base  194  is mounted on base mount  199  so that the shift arm  196  pivots at a 45 degree angle relative to the vertical axis of torque limiter  192 . This enables the shift arm  196  to fall with the force of gravity against one of the lugs to drive either the reel unit  172  or the drive cone unit  182 , as described with respect to  FIGS. 8A and 8B . 
     Since the shift arm  196  for the left-hand system has been rotated 90 degrees relative to the shift arm  96  for a right-hand system, shift arm  196  will pivot and fall in response to gravity 90 degrees differently than discussed with respect to a right-hand system. However, since a left-hand system has the pool cover motor system components located in a mirror image to a right-hand system, the shift arm  196  still falls in the correct directions to drive the reel assembly  172  and the drive cone assembly  182  correctly for a left-hand system, as described above. 
       FIG. 10B  shows torque limiter  192  mounted on drive shaft  180 . The shift arm  196  has pivoted to contact the reel disc lug  200   a,  so as to drive reel unit  172  in a counter-clockwise rotation, as further described in connection with  FIG. 9A . 
     In summary, the pool cover motor systems of the present embodiments offer a number of advantages. The gear mechanisms  90  and  190  for right-hand and left-hand systems of the present embodiments use simple components with only one moving part that pivots in response to gravity. Moreover, gear mechanisms  90  and  190  use the same components. Gear mechanism  90 , shown in  FIG. 8A  can easily be changed to become gear mechanism  190  shown in  FIG. 10A  by simply removing bolt  126  and rotating shift base  94  by 90 degrees relative to base mount  99  to place it in the position of shift base  194  shown in  FIG. 10A . This simple gear structure eliminates the need to stock separate right-hand and left-hand pool cover motor assemblies. One pool cover motor assembly functions as either a right-hand or left-hand assembly by simply changing the gear mechanism as described above. 
     A further simplification over the prior art is provided by mounting the torque limiters  92  and  192  on drive shafts  80  and  180 , respectively, to connect to the respective gear mechanism  90  and  190 . Thus, the torque limiter provides the necessary fixed connection of the gear mechanism to the drive shaft, as described above. Accordingly, the use of a torque limiter connected to the gear mechanism performs both the functions of securing the gear mechanism to the drive shaft and limiting the amount of torque applied to the gear mechanism and to the pool cover motor assembly generally. This structure substantially simplifies the task of including a torque limiter as part of the pool cover motor assembly and reduces the cost of manufacturing accordingly. 
     While this disclosure has been described as having a preferred design, the present disclosure can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.