Patent Publication Number: US-2013234418-A1

Title: Collapsible  golf bag cart with improved folding mechanism

Description:
This is a non-provisional application, claiming priority from U.S. provisional applications Nos. 61/608,503 by one of the same inventors, filed 8 Mar. 2012, and 61/692,575 by the same inventors, filed 5 Sep. 2012. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to accessories for golfers and particularly to golf bag carts (push carts) and methods for transporting golf bags used by golfers. 
     BACKGROUND ART 
     Although the purists in the golf community insist that the only way to properly play golf is to carry the golf bag, either personally or through the use of a caddy, many golfers prefer to use carts to transport the golf bags and associated equipment. While riding carts are required by many courses, a great number of players desire to gain the exercise benefits of walking during the round, without carrying the bag and equipment. For this reason walking carts are popular. 
     For many years pull carts, usually two-wheeled, were the norm. However, with the introduction in 2000 of the SPEED CART® three-wheeled push cart (U.S. Pat. Nos. 6,698,789 and 7,128,333) from Sun Mountain Sports, Inc. the landscape changed. Push carts, particularly collapsible push carts, have become the most popular versions. 
     Developments have continued, including the inventor&#39;s own Micro-Cart® model, also from Sun Mountain Sports, Inc. which reduced the size and weight of the cart, particularly of the footprint in the compact mode. 
     Nonetheless, demand continues for more compact, more stable, more convenient and lighter golf bag carts. 
     DISCLOSURE OF INVENTION 
     Accordingly, it is an object of the present invention to provide an improved collapsible golf bag cart for transporting a golf bag in a highly stable manner. 
     Another object of the invention is to provide a bag cart system which transitions by expansion and collapsing between a folded (compact) state and an expanded (operational) state with minimal effort and an elegant mechanism. 
     A further object of the present invention is to provide a bag cart system with improved geometry for greater stability and strength per weight than prior versions. 
     Yet another object of the invention is to provide a cart which collapses into a compact mode which has a minimal footprint and a minimal height. 
     Another object of the invention is to provide a multi-position handle arrangement for the convenience of the golfer, allowing the golfer to propel the bag cart from behind or from the side. 
     Still another object of the invention is to provide a cart structure where each of the folded components has approximately the same longitudinal extent, for minimal folded size. 
     Yet another object is to provide a cart structure where the folded components nest effectively with each other for compactness. 
     Briefly, one preferred embodiment of the present invention is a golf bag push cart having a base frame, a torso frame, and a rear wheel subassembly, all radially extending from a central pivot joint subassembly, with a front wheel subassembly, a handle subassembly pivotally mounted on the distal ends of the frame components. The pivot joint includes a central transverse axle and a reciprocal rotational gear (RRG) assembly which operate together to control the positioning of the rear wheels in accordance with the relative rotational positions of the base frame and torso frame of the bag support system. Rotationally separating the torso frame and the base frame operates the RRG to rotate the rear wheel position rearward and laterally expand the position outward from a compact (folded) mode to an expanded mode for use by a golfer. The front wheel subassembly and the handle subassembly are separately manually expanded. Top and bottom bag cradles are provided on the bag support to receive a golf bag for rolling transport. The handle subassembly includes handle grips which are pivotally mounted to adjust to most efficient vertical position for the user&#39;s convenience. 
     An advantage of the present invention is that it provides great stability: with a substantial rear wheel base in the expanded mode; a central pivot point for the rear wheels; and a centralized balance point (with a center of gravity relatively low to the ground). 
     Another advantage of the invention is that it has a wheelbase which is greatly expanded on two axes when expanded, thus providing excellent stability when loaded with a golf bag. 
     Yet another advantage of the present invention is that the tapered shapes of each extension from the central pivot point and the cast or extruded construction of structural components provide optimal strength while the lightweight materials result in a lightweight cart which is easily lifted and handled by most golfers. 
     Still another advantage of the present invention is that the compound actions provided by the unique RRG pivot joint structure for the wheels and the frame members results in greater height and width in the use mode, without sacrificing stability. 
     A still further advantage of the present collapsible golf bag cart invention is that the dual front wheel yoke facilitates folding until the common axle hits the base frame, with the front wheels passing under and past the base frame, nesting inside the rear wheels, for minimal height in compact mode. 
     Yet another advantage of the present invention is that the lateral spacing of the components allows each to nest effectively with the others, minimizing the width and height of the compact mode. 
     Another advantage of the present invention is that the base struts, torso strut and leg struts are shorter in length than in prior folding carts, as facilitated by the central pivot axle, which provides greater overall strength with lighter materials. 
     These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of the best presently known mode of carrying out the invention and the industrial applicability of the preferred embodiment as described herein and as illustrated in the several figures of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The purposes and advantages of the present invention will be apparent from the following detailed description in conjunction with the appended drawings in which: 
         FIG. 1  is a perspective view of the expanded mode of the present invention; 
         FIG. 2  is a front view of the invention in the expanded mode of the invention; 
         FIG. 3  is a rear plan of the expanded mode of the invention; 
         FIG. 4  Is a perspective view of the compact mode of the present invention; 
         FIG. 5  is a top plan view of the golf bag cart of the present invention, shown in the folded mode; 
         FIG. 6  is a side elevational view of the preferred embodiment in the compact mode; 
         FIG. 7  is a detail front right perspective view of the pivot joint subassembly; 
         FIGS. 8   a  and  8   b  are opposing perspective detail views of the interior components of the pivot joint subassembly, without the frame and leg members attached; and 
         FIGS. 9   a ,  9   b , and  9   c  are partially cut away side detail views of the pivot joint subassembly, shown respectively in the expanded, transitional, and compact mode positions. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     The present invention is collapsible golf bag cart with improved folding mechanism used to transport golf bags loaded with golf clubs and accessories. The collapsible cart is referred to by the general reference character  10  in the drawings and description. The collapsible cart  10  may be used with various golf bags and may exist in multiple embodiments. 
     In one preferred embodiment of the invention illustrated in  FIG. 1 , the collapsible cart  10  is shown in a perspective view as appropriate for transporting a typical golf bag  12  (not shown). The cart  10  is illustrated in  FIGS. 1-3  in an expanded mode  14 , also known as the “use” mode, where it is capable of carrying and transporting the golf bag  12 . The invention is illustrated in  FIGS. 4-6  in a compact mode  16  or “folded” mode where it is collapsed into a minimal volume configuration for storage in an auto trunk compartment or garage, for example. 
     The preferred embodiments  10  are generally laterally symmetrical about a vertical plane  18  (see, especially,  FIGS. 2 ,  3  and  5 ) with corresponding left and right components (or components which are bisected by the plane  18 ). The cart  10  may be thought of as having various principal assembles or subsystems which operate together in order to function as a compact, lightweight and extremely easy to use method of transporting a golf bag on the rolling surfaces of a golf course and in other locations such as parking lots and storage facilities. The primary subassemblies include a bag support frame  20 , a front wheel subassembly  22 , a rear wheel subassembly  24 , a pivot joint subassembly  26 , and a handle subassembly  28 . It is understood that some components of the invention interface with others and may be considered to be a part of more than one of the subassemblies. The pivot joint subassembly  26  is the fulcrum and central component of the overall cart  10  so terms such as proximal and distal refer back to that component. 
     The bag support subassembly includes a base frame  30  on one side of the pivot joint subassembly  26  and a torso frame  32  on the other. The preferred base frame  30  includes a pair of symmetrical base struts  34 , each pivoting at the proximal end on the pivot joint  26  and being spanned by a cross pin  36  at the distal end, with an intermediate gap  38  therebetween. As shown particularly in  FIG. 1 , each base strut  34  is tapered so as to have a greater vertical height at the proximal end and a lesser height at the distal end. The base frame  30  and the torso frame  32  have approximately the same longitudinal length. 
     A bottom bag cradle  40  is mounted on the cross pin  36  so as to pivot over a limited arc from a support position ( FIGS. 1-3 ) to a storage position ( FIGS. 4-6 ). 
     The torso frame  32  has only a single torso strut  42  in the preferred embodiment. The torso strut  42 , like the base struts  34  is tapered from its proximal end at the pivot joint  26  to its distal end. The proximal end of the torso strut  42  interfaces with the pivot joint  26  intermediate the two base struts  34  and is adapted to nest into the intermediate gap  38  in the compact mode  16  ( FIGS. 4 and 5 ). The distal end of the torso strut  42  includes a dogleg  44  which terminates at a toothed handle attachment pivot  46  while a top bag cradle  48  is attached at a top cradle mount  50  situated at or near the dogleg  44 . The top bag cradle  48  is adapted to elastically and mechanically adjust to receive and support the upper portion of the golf bag  12  to keep it in position during use. 
     The front wheel subassembly  22  includes a yoke  52  pivotally mounted on the cross pin  36 . The yoke  52  includes a pair of yoke arms  54  spaced apart just wider that the width of the base frame  30  such that in the compact mode  16 , the yoke arms  54  may nest about the base struts  34  (see  FIG. 5 ). Each yoke arm supports an exterior axle  56  upon which a corresponding front wheel  58  is mounted. In this manner the front wheels  58  do not block the space between the yoke arms  54  and inhibit minimal space nesting. A yoke lock lever  60  is provided at one end of the cross pin  36  to manually lock the yoke  52  in the expanded mode  14  of  FIGS. 1-3  or the compact mode  16 . 
     The rear wheel subassembly  24  also pivots and expands laterally and rearward from the pivot joint  26 . The entire rear wheel subassembly  24  has approximately the same longitudinal length as do the base struts  34  and torso strut  42 . As with the other main components, the the rear wheel subassembly  24  is symmetrical about the bisecting plane  18  and includes a pair of symmetrical suspension subsystems  62 , spaced to each side of the bisecting plane  18  (see  FIGS. 2 ,  3  and  5 , particularly). In each suspension subsystem  62 , a central axle  64  extends into the pivot joint subassembly  26  (see further discussion with respect to  FIGS. 7 ,  8  and  9 ) and attaches to a spacer bracket  66  upon which a mounting plate  68  is secured. In at least the preferred embodiment, the spacer bracket  64  is integrally formed with the mounting plate  68  to form a single unitary piece. 
     The suspension subsystems  62  are a variation on the inventor&#39;s parallelogram suspension systems found on prior golf bag carts of Sun Mountain Sports, Inc. (see, e.g. U.S. Pat. Nos. 6,698,789 and 7,128,333). In the present case, a broad tapered structural leg strut  70  is pivotally mounted on the mounting plate  68  at its proximal end and to an axle pivot bracket  72  at its distal end. In parallel array to the leg strut  70 , a parallel link  74  member is also pivotally connected to the mounting plate  68  and the axle pivot bracket  72 . On at least one side of the cart, a manually activated pin and gap brake  75  is placed intermediate the axle pivot bracket  72  and a rear wheel  76 . The rear wheels  76  are then rotationally supported on rear axles  78  associated with the axle pivot brackets  72 . As described in the inventor&#39;s prior patents, this parallelogram suspension method maintains extremely stable and secure positioning and support of the rear wheels  76  in the expansion mode  14 , the compact mode  16  and during the transitions between these modes. 
     The structures associated with and/or parts of the spacer bracket  66 /mounting plate  68  are best illustrated in  FIGS. 7 ,  8   a,  and  8   b.  A strut bracket  80  is centered on the origin of the circular mounting plate  68  for mounting the associated rear leg strut  70  thereon, utilizing a strut pin  82  which extends though the leg strut  70  on each side of the strut bracket  80 , through the portions of the strut bracket  80  on each side of the central axle  64  and also through the central axle  64  itself. The leg strut  70  pivots about the strut pin  82  and includes an extension portion  84  which extends beyond the fulcrum provided by the strut pin  82 . 
     Similarly, a link bracket  86  is provided parallel to and separated from the strut bracket  80  to pivotally mount the proximal end of the parallel link  74 . A link pin  88  (see  FIG. 2 ) pivotally supports the parallel link  84 . 
     An expansion slide aperture  90  for slidably receiving an expansion slide post  92  extends axially though the mounting plate  68  and the associated spacer bracket  66  at a position radially offset from the central axle  64  opposite the side of the link bracket  86 . Similarly, a retraction slide aperture  94  receives a retraction slide post  96  at a position radially offset toward the link bracket  86 . 
     It may also be seen in the illustration of  FIG. 7  that the interior facing surfaces of the proximal ends of the base struts  70  are provided with a leg deployment ramp  98  which interacts with the expansion slide post  92  and the retraction slide post  96  as hereinafter described. 
     The pivot joint subassembly  26 , and particularly the transverse central axle  64  which extends therethrough, constitute the core fulcrum component of the present invention  10  in that the positioning and alignment of all of the other subassemblies are primarily controlled by this structure. The pivot joint subassembly  26  is best understood in connection with  FIGS. 7 ,  8  ( 8   a  and  8   b ) and  9  ( 9   a,    9   b  and  9   c ). In  FIG. 7   a,  a detail right front perspective view of the fully assembled joint structure  26  is shown in the expanded mode  14 , while in  FIGS. 8   a  and  8   b  the interior components of the joint are shown in different perspectives.  FIGS. 9   a,    9   b  and  9   c  illustrate a cut-away side view of the joint  26 , with  FIG. 9   a  illustrating the situation in the expanded mode  14 ,  FIG. 9   c  showing the compact mode  16 , and  FIG. 9   b  illustrating an intermediate position during transition. It is noted that the opposite side base strut  34  is shown, with the near side base strut being cut away, so the internal elements shown are not the ones associated with the base strut illustrated. 
     In  FIGS. 7  it may be seen that the central axle  64  (which extends completely through the pivot joint subsystem  26 ) and the spacer brackets  66 /mounting plates  68  all laterally extend beyond the base struts  34 . The torso frame  32  is fixedly attached to joint subassembly  26  on the bisecting plane  18 , such that moving the torso strut  42  acts to rotate the central axle  64  (as discussed below with respect to  FIG. 9 ). A protective sheath  100  minimizes the amount of dirt, dust and other foreign matter into the interior of the joint  26 . Side sheaths  102 , not shown in  FIG. 7 , but see especially  FIGS. 2 ,  4  and  5 , extend over the spacer brackets  66  and the central axle  64  between the base struts  34  and the mounting plates  68  to prevent influx of fouling agents from those directions. 
     The inner workings of the pivot joint subassembly  26  are shown particularly in  FIGS. 8 and 9  and the following discussion deals with both illustrations, with some elements being more prominent in one figure or another. 
     As shown in  FIGS. 8 and 9 , a pair of partially internally toothed ring gears  104  are provided about, but not directly connected to, the central axle  64 . Each ring gear  104  is fixedly connected to a corresponding base strut  34  by connecting bolts  106 . The base frame  30  and the ring gears  104  provide the “rotationally stationary” components of the cart  10 , with everything else being supported thereby. 
     Radially within each ring gear  104 , surrounding and affixed to the central axle  64 , is a central gear  108 . Mounted intermediate the central gear  108  and the ring gear  104  are a ratio gear  110 , an interior reversing gear  112  and an exterior reversing gear  114 . The ratio gear  110  and the interior reversing gear  112  are axially offset and (in the preferred embodiment) affixed to each other to be commonly carried on an interior shaft  116  with the ratio gear  110  mating with the central gear  108 . Similarly, the exterior reversing gear  114  is carried on an exterior shaft  118  and mates with both the interior reversing gear  112  and the corresponding ring gear  104 . The interior shaft  116  and exterior shaft  118  each pass through (with at least the interior shaft  116  being rotationally free on bearings in the preferred embodiment) the torso strut  42 , so as move therewith (see  FIG. 9 ). Each set of gears is duplicated on each side of the bisecting plane  18  to provide stability and balance, with each ring gear  104  being associated with one of the base struts  34 . Together, the various gears components form a reciprocal rotational gear (“RRG”) assembly  120 . The RRG assembly  120  facilitates the conversions between the expanded mode  14  and the compact mode  16 , as shown in  FIGS. 9   a,    9   b,  and  9   c.    
     A stop wedge  122  is provided on each central gear  108  to, at the extremes of rotation of the central axle  64 , abut against a fixed expansion limiter  124  and compact limiter  126 . The limiters  124  and  126  are mounted on the torso strut  42 . 
     A spring loaded pivot lock lever  128  is pivotally affixed to, extends about and brackets the torso frame  32 . The pivot lock lever  128  is used to lock the rotational position of the torso strut  42  in place in the expanded mode  14  or is pressed to release the torso strut  42  to rotate the central axle  64  with respect to the base frame  30  in order collapse the cart  10  into the compact mode  16 . The spring mounted pivot lock lever  128  (see  FIGS. 8   a  and  8   b ) raises or lowers a catch pin  130  which will engage an expanded slot  132  on the ring gear  104  in the expanded mode  14  ( FIG. 9   a ), ride on the exterior surface of the ring gear  104  in transition ( FIG. 9   b ) and engage a compact slot  134  in the compact mode  16  ( FIG. 9   c ). This facilitates locking the cart  10  into either the expanded mode  14  for use on the course or the compact mode  16  for storage, with an easy transition therebetween. 
     The operation of the pivot joint assembly  26  is primarily illustrated in  FIGS. 9   a - 9   c.  In the view of  FIG. 9   a,  the cart  10  is shown in the expanded mode  14 , with the torso frame  32  being at about a 130° angle to the base frame  30  and the leg strut  70  extending rearward from the pivot joint  26  and outward from the center plane  18 . This is the same condition illustrated in  FIGS. 1 and 7 , with the rear wheel assemblies supporting the pivot joint  26  substantially above the ground surface. The pivot lock lever  128  is engaged; with the catch pin  130  engaged with the expanded slot  132 . The central gear is positioned such that the stop wedge  122  is abutting against the expansion limiter  124 . 
     Conditions exterior to the cutaway of  FIG. 9   a  are shown in  FIG. 7 . When the central axle  64  is rotated to this extent, the mounting plate  68  is rotated such that the leg deployment ramp  98  engages the retraction slide post  96  to a minimal degree and the expansion slide post  92  to the maximal degree. This causes the expansion slide post  92  to protrude through the mounting plate  68  and force the leg strut  70  outward (the rotation of the central axle  64  forces the leg strut  70  backward). It is noted that when the rotation to the compact mode  16  occurs, the opposite condition obtains and the retraction slide post  96  is forced outward against the extension portion  84  such that the leg strut  70  is urged inward toward the frame. 
     When it is desired to fold the cart  10  into the compact mode  16 , the pivot lock lever  128  is disengaged and the catch pin  130  is released from the expanded slot  132  and rides along the outside of the ring gear  104 . In the transitional mode illustrated in  FIG. 9   b,  the torso frame  32  has been rotated to an angle of about 60° to the base frame  30 . The rotation of the torso strut  42  causes the interior shaft  116 , the exterior shaft  118 , and their associated gear components in the RRG assembly  120  (ratio gear  110 , interior reversing gear  112  and exterior reversing gear  114 ) to move accordingly with respect to the central gear  108 . In this manner the interaction between the ring gear  104  and the exterior reversing gear  114  rotates the interior reversing gear  112  to drive the interior shaft  116  such that the ratio gear  110  engages the central gear  108  and drives it in the opposite direction to the rotation of the torso frame  32 . This rotates the central axle  64  to drive the rear wheel suspension systems  62  forward as the retraction slide post  96  forces the rear wheels  76  inward. During this transition the pivot joint  26  will begin to descend toward the ground surface, once the leg suspensions  66  begin to approach parallel with the base frame  30 . 
     When the rotational limit is reached, as shown in  FIG. 9   c,  the central gear  108  will have been driven such that the stop wedge  122  abuts against the compact limiter  126  and the catch pin  130  snaps into the compact slot  134 . In this position, the base frame  30 , the torso frame  32  and the leg struts  70  are all generally co-aligned, as shown in  FIG. 6 , and the cart  10  is ready for storage. 
     Turning now to the handle subassembly  28  as shown in  FIGS. 1-3 , an open-Y-shaped handle frame  136  is pivotally attached in a lockable ratchet manner to the handle pivot  46  at the upper end of the torso frame  32  such that the angle of the handle subassembly  28  with respect to the torso frame  32  may be adjusted for the user&#39;s comfort. In addition to the handle frame  136 , the handle subassembly  28  includes a pair handle grips  138  at the upper lateral extents. 
     In the preferred embodiment, each handle grip  138  is individually pivotally attached to the handle frame at a grip pivot  140  so that it may rotate to different vertical orientations for the convenience of the user. This allows the handle grips  138  to be position to extend generally outward ( FIGS. 1-3 ), fold down to a compact position, ( FIGS. 4-6 ) or rotate upward for easy gripping from the side of the cart  10 , when the user wishes to guide the cart from the side. The grip pivot  140  is preferably a ratchet structure mating with the grip handle  138  and being lockable by the user in any position within the range of rotation. This facilitates the user maneuvering the cart  10  while being positioned behind behind it or walking along side of it so as to control the cart  10  with one hand. 
     The handle subassembly  28  of the preferred embodiment  10  also may include a variety of convenience features for the use of a golfer during a round of golf. As these are not critical to the present invention they are not specifically shown or enumerated in the drawing, but are described in the inventor&#39;s prior patents applications. One feature which is shown is a storage console  142  with a lid  144  hingedly attached thereto. The storage console  140  provides a compartment where the golfer can place yardage books, golf balls, notes, a slim wallet or other items to which occasional access may be desired during the round. Other features such as tee apertures and pencil apertures may be formed in the extended frame of the console  142  to receive and store frequently accessed golf tees and pencils during the round. Additionally and optionally, the cart  10  may include a drink holder. 
     A further innovation inherent in the preferred deluxe embodiment of the invention is a score card plate  146 . The score card plate  146  may either be fixed in a 90° angle to the handle frame  134  (See  FIGS. 4 and 6 ) or may be rotatably mounted to adjust to a comfortable angle for use by the golfer. Various mechanisms (clamps, magnetic retainers or the like, may be utilized to affix a score card to the score card holder  146 . 
     In order to minimize wobble or similar problems which may be caused by imperfect manufacturing tolerances, it is desirable to provide mechanisms for adjusting the spacing of some of the elements in the vicinity of the pivot joint subassembly  26 . To maintain axial pressure between the spacer brackets  66 /mounting plates  68  and the central gears  108  a pair of threaded adjustment sockets  148  are provided in each mounting plate  68  (See  FIG. 8   b ) to receive a first adjustment screw  150  and a second adjustment screw  152 . The preferably Allen-headed adjustment screws  148  and  150  extend through to abut against a spacer plate  154  (See  FIGS. 7 ,  8   a  and  8   b ) such that proper axial tension may be maintained. 
     It is also particularly desirable that a firm pressure be maintained for the expansion slide post  92  against the leg deployment ramp  98  for proper functioning. To this end an expansion adjustment screw  156  extends through each leg strut  70  (see  FIGS. 1 ,  4  and  6 ) to abut against the distal end of the expansion slide post  92 . Tightening the Allen-headed expansion adjustment screw  156  maintains firm contact between the proximal end of the expansion slide post  92  and the leg deployment ramp  98 . 
     It is noted that, while the RRG  120  greatly facilitates folding and unfolding the cart  10 , an alternate embodiment is envisioned where the torso frame is completely independent of the central axle  64 . In such an embodiment the expansion and retraction of the rear leg assembly  28  may be accomplished manually. Grasping a rear wheel  78  and manually rotating the central axle  64  will cause the interaction of the leg deployment ramp  98  with the slide posts  92  and  96  to force the distal ends of the leg struts  70  inward or outward (depending on the direction of rotation) in conjunction with the rotation. The torso frame would then be independently extended or folded inward, either before or after the legs and wheels. 
     The preferred embodiment is primarily constructed of cast anodized aluminum for light weight and durability. The wheels  58  and  76  are formed of lightweight structural plastic with cushioned traction surfaces and may either be provided with solid hubs or spoke hubs. In some embodiments rubberlike friction surfaces are also provided. 
     Many modifications to the above embodiment may be made without altering the nature of the invention. The dimensions and shapes of the components and the construction materials may be modified for particular circumstances or types of bags to be carried. 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not as limitations. 
     INDUSTRIAL APPLICABILITY 
     The collapsible golf bag cart  10  of the present invention is intended for use primarily by golfers who desire maximum convenience and safety while transporting a golf bag on a walking round. The cart  10  is lightweight and is can be folded into an extremely compact form to facilitate storage. It expands and folds with a minimum of effort. The expanded mode  14  is very stable for rolling and supporting the golf bag  12  during the round. The cart  10  also requires no straps or other fasteners to retain and support the golf bag, thus minimizing the amount of loose or dangling components and reducing effort. 
     For typical use, the golf bag cart  10  will begin in the compact mode  16 , for storage. In this mode it has only the effective height of the rear wheels  76  and a lateral extent approximately equal to the width of the rear wheels  76  themselves plus the width of the pivot joint subassembly  26  so the cart easily fits into an automobile trunk or on a garage shelf. Even in collapsed mode  16 , however, the wheels  24  are free to rotate and the cart  10  can be rolled to desired locations (providing that the friction brake  75  is not engaged). 
     When the golfer has moved the folded mode  16  cart to the desired location it is time to expand it to the mode where it is feasible to load a golf bag  12 . To do this the golfer simply grasps the torso frame  32  (or the handle frame  136 , as desired), disengages the pivot lock lever  128  and pulls upward from the base frame  30 . This causes the RRG assembly  120  to rotate the central axle  64  which causes the rearward rotation and lateral expansion of the suspension system  62  of the rear wheels  76 . As the rear wheels  76  will typically be on the ground this results in the fulcrum position of the pivot joint subassembly  26  to be lifted upward, resulting in the base struts  34  being angled upward and the torso strut  32  angling rearward of vertical to a lesser degree than if the base struts  34  remained horizontal to the ground. The shaping of the expanded cart also provides a gap such that the pockets of the golf bag  12  may comfortably fit between the bag and the pivot joint  26 . 
     The front wheel subassembly  22  may be transitioned to the expanded mode either before or after the bag support subassembly  24 . This expansion of the front wheel subassembly  22  is accomplished by manually releasing the yoke lock lever  60  and rotating the yoke  52  and front wheels  58  around the cross pin  36  to a position forward of and under the bag bottom cradle  40 . The yoke lock lever  60  is then again engaged to lock the position. 
     Similarly, the handle subassembly  28  may be positioned time-independently of the bag support subassembly  24 . The handle frame  136  is manually rotated about the handle pivot  46  to the desired position and secured at the optimal angle for the particular user. The angles of the handle grips  138  are also adjusted to the user&#39;s preference. 
     Once the cart  10  is in the expanded mode ( FIGS. 1-3 ) the user will load the golf bag  12  such that the bag bottom is supported within the bag bottom cradle  40  and the collar or top of the bag is elastically captured in the resilient bag top cradle  48 . The user then is positioned either directly behind the handle so as to be able to grasp either or both of the handle grips  136 , or to one side in order to grasp only one of the handle grips  136 . Thus the user can choose either to propel the cart  10  by pushing directly from behind or by guiding and pushing/pulling from a position walking beside the cart  10 . 
     When the round is over, the golfer simply: removes the bag  12  from the cart  10 ; and reverses the above steps to return the cart  10  to the compact mode  16  and stores it again. 
     The extreme convenience, ease of operation, compactness of storage volume and light weight of the inventive cart  10  make it a joy to own and use and a desirable accessory for any golfer who wishes to walk the course without carrying the weight of the bag. 
     For the above, and other, reasons, it is expected that the collapsible golf bag cart  10  of the present invention will have widespread industrial applicability. Therefore, it is expected that the commercial utility of the present invention will be extensive and long lasting. 

 
     IN THE CLAIMS 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.