Patent Publication Number: US-8968159-B2

Title: Folding elliptical exercise machine

Description:
RELATED APPLICATIONS 
     The application claims priority to Taiwan Application Serial Number 101117946, filed May 18, 2012, which is herein incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an indoor exercise machine. More particularly, the present disclosure relates to a folding elliptical exercise machine. 
     2. Description of Related Art 
     The applicant discloses a folding elliptical exercise apparatus as disclosed in U.S. Pat. No. 7,946,962. The footprint of the elliptical exercise apparatus is much more compact after folding. In addition, a user can quickly and conveniently operate the folding or unfolding procedures. With a traditional folding elliptical exercise apparatus, the linked elements such as crank mechanisms, foot pedals, and handle links are not locked while the elliptical exercise apparatus is folded. The linked elements may be moved by an external force or a shift of their centers of gravity, and this movement may occur randomly and in an uncontrolled manner, possibly during the folding process, the unfolding process, or while transporting the elliptical exercise apparatus. This uncontrolled and unintended motion is undesirable in an elliptical exercise apparatus. 
     U.S. Pat. Publication No. 2008/0280733 discloses another type of a folding elliptical exercise apparatus which has a mechanism for locking a crank unit while the elliptical exercise apparatus is oriented in a storage position. The user turns a locking mechanism which fastens a predetermined pin of the crank unit for locking a crank mechanism. However, the foregoing technique is not automatic, and requires an extra step for engaging the locking mechanism to lock the crank mechanism, so that the operation will be very inconvenient. 
     SUMMARY 
     According to one embodiment of the present invention, a folding elliptical exercise machine includes a main frame, a guider frame, a rotatable crank mechanism, two supporting members, two pedals and a locking device. The guider frame is pivotally coupled to the main frame for being moved between a use position and a storage position, and the guider frame has two tracks. The rotatable crank mechanism has a crank shaft, two crank units, a flywheel and a transmission mechanism. The crank shaft is pivotally arranged on the main frame. The two crank units are fixed on two ends of the crank shaft respectively. The flywheel is pivotally coupled to the main frame. The transmission mechanism is coupled to the crank units and the flywheel. Each of the two supporting members respectively has a rotating portion, a reciprocating portion and a supporting portion. The two rotating portions are pivotally coupled to the two crank units respectively, and move along a circular path about the crank shaft. The two reciprocating portions are carried by the two tracks respectively. The two reciprocating portions are movable back and forth along the two tracks respectively while the guider frame is oriented in the use position. The two pedals are respectively coupled to the two supporting portions of the two supporting members. The locking device is arranged between the guider frame and the rotatable crank mechanism, the position of the locking device is affected by the position of the guider frame, and the locking device has a latch having an unlocked position and a locking position. When the guider frame is oriented in the use position, the latch is set to the unlocked position so that it does not interfere with the rotation of the rotatable crank mechanism. When the guider frame is moved from the use position to the storage position, the latch set to the locking position to prevent a predetermined element of the rotatable crank mechanism from rotating. 
     According to another embodiment of the present invention, a folding elliptical exercise machine includes a main frame, a guider frame, a rotatable crank mechanism, two supporting members, two pedals and a locking device. The guider frame is pivotally coupled to the main frame for being moved between a use position and a storage position, and the guider frame has one or more guide tracks. The rotatable crank mechanism has a crank shaft, two crank units, a large pulley, a flywheel and a transmission mechanism. The crank shaft is pivotally arranged on the main frame. The two crank units are fixed on two ends of the crank shaft respectively, and rotation of the two crank units simultaneously rotates the two crank units and the large pulley about the crank shaft. The large pulley has two catches which are spaced 180 degrees apart from each other on the large pulley. The flywheel is pivotally coupled to the main frame. The transmission mechanism is coupled to the large pulley and the flywheel. The two supporting members are coupled to the respective crank unit so that each supporting member has a first portion, a second portion and a supporting portion. The two first portions are pivotally coupled to the two crank units respectively, and rotatable about the crank shaft. The two second portions are constrained by the one or more guide tracks respectively to move along a reciprocating path while the guider frame is oriented in the use position. The two pedals are respectively coupled to the two supporting portions of the two supporting members. The locking device is operatively coupled to the guider frame and the rotatable crank mechanism, the movement of the guider frame as the guider frame is pivotally moved with respect to the main frame engages and disengages the locking device. The locking device has a latch movable between an unlocked position and a locking position. The latch is retracted into an unlocked position when the guider frame is positioned in the use position. The latch is extended into a locking position when the guider frame is pivotally rotated away from the use position so that the latch will engage with one of the two catches on the large pulley when the large pulley is rotated into a position where one of the two catches aligns with the latch, thereby preventing rotation of the rotatable crank mechanism. 
     The locking device is configured to engage the lock between the large pulley and the main frame as the guider frame is pivotally rotated from the use position to the storage position. When the large pulley is locked so as to prevent it from rotating with respect to the main frame, the large pulley, the crank units, the supporting members and the pedals are prevented from engaging in any uncontrolled or unintended motion. The locking device is configured to disengage the lock between the large pulley and the main frame as the guider frame is pivotally rotated from the storage position back to the use position. When the large pulley is unlocked so as to allow it to freely rotate with respect to the main frame, the supporting members and the pedals are permitted to move in relationship to the guider frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  and  FIG. 2  are perspective views of a folding elliptical exercise machine which is oriented in a use position according to one embodiment of the present invention; 
         FIG. 3  is a lateral view of  FIG. 2 ; 
         FIG. 4  is a perspective view of the folding elliptical exercise machine which is oriented in a storage position; 
         FIG. 5  is a lateral view of  FIG. 4 ; 
         FIG. 6  is also a lateral view of the folding elliptical exercise machine which is oriented in the storage position, but with the relative position of various elements opposite to that shown in  FIG. 5 ; 
         FIG. 7  is a detail view of  FIG. 2 ; 
         FIG. 8  is a detail view of  FIG. 4 ; and 
         FIG. 9A  to  FIG. 9D  are schematic movement diagrams of a locking device while the folding elliptical exercise machine is moved from the use position to the storage position. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. 
     In other instances, well-known structures and devices are schematically depicted in order to simplify the drawings. 
       FIG. 1  and  FIG. 2  are perspective views of a folding elliptical exercise machine which is oriented in a use position according to one embodiment of the present invention.  FIG. 3  is a lateral view of  FIG. 2 . As shown in  FIGS. 1-3 , a folding elliptical exercise machine  1  includes a main frame  10 , a guider frame  20 , a rotatable crank mechanism  30 , two supporting members  40 , two pedals  50  and a locking device  60 . The guider frame  20  is pivotally coupled to the main frame  10  for being moved between a use position and a storage position. The rotatable crank mechanism  30  is arranged on the main frame  10 . One end of each of the two supporting members  40  are coupled to the rotatable crank mechanism  30 , and the other ends are carried by the guider frame  20 . One end of each of the two supporting members  40  is therefore constrained to move about a circular path, and the other end of each of the two supporting members  40  is therefore constrained by the guider frame  20  to move along a reciprocating path, so that these two motions are combined to form an elliptical-like closed path in between these two ends of each of the two supporting members  40 . The two pedals  50  are coupled to the two supporting members  40  respectively for carrying the two respective feet of a user. When the folding elliptical exercise machine  1  is oriented in the storage position, the locking device  60  is used for locking the rotatable crank mechanism  30 . Due to the two supporting members  40  being coupled to the rotatable crank mechanism  30 , when the rotatable crank mechanism  30  is locked, the other elements such as the supporting members  40  also become correspondingly locked. 
     The main frame  10  is arranged on a floor. The present embodiment of the main frame  10  includes a base  11 , a rack  12 , a post  13  and a handgrip  14 . The base  11  rests on a ground surface. The rack  12  is mounted on a top of the base  11 . The post  13  is formed by a top portion of the rack  12 . The handgrip  14  is arranged on a top portion of the post  13  for the user to grip while exercising. In addition, the present embodiment can be equipped with a control console on the top end of the post  13  as well. 
       FIG. 4  is a perspective view of the folding elliptical exercise machine which is oriented in a storage position.  FIG. 5  is a lateral view of  FIG. 4 . As shown in  FIGS. 2-5 , the guider frame  20  is pivotally coupled to the main frame  10  and has two tracks which are parallel. Each track  21  has a front end  21   a  and a rear end  21   b . The front ends  21   a  of the two tracks extend to form an arm  23 . A front end of the arm  23  is pivotally coupled to a rear end of the rack  12  via a guider shaft A 1  so that the guider frame  20  can be rotated in relation to the main frame  10  between a use position (shown in  FIGS. 1-3 ) and a storage position (shown in  FIGS. 4-6 ). In the embodiment shown, the angle between the use position and the storage position is about eighty degrees. 
     As shown in  FIG. 3 , pads of the guider frame  20  are rested on the ground surface while the guider frame  20  is oriented in the use position. The two tracks  21  are substantially parallel to the ground surface. As shown in  FIG. 5 , when the guider frame  20  is rotated up to be oriented in the storage position, an angle between the two tracks  21  and the ground surface is about eighty degrees. 
     The main frame  10  has a two-position ROM plate  15  which is fixed to the rack  12  and is located near the front end of the arm  23 . The two-position ROM plate  15  is a curved plate with a substantially constant radius which takes the guider shaft A 1  as a center and has a first hole  15   a  and a second hole  15   b  (see  FIGS. 7-8 ). The first hole  15   a  and the second hole  15   b  are separated by an angular distance of eighty degrees as measured from the guider shaft A 1 . The angular distance and the angle between the use position and the storage position are the same. 
     The control methods and the operation of the guider frame  20  are similar to the embodiment disclosed in the U.S. Pat. No. 7,946,962. The guider frame  20  has a pull-pin locking mechanism  70  including a switch  71  which is arranged on a rear end of the guider frame  20 , a pin  72  which is arranged on a front end of the arm  23 , a pin spring (not shown) which is configured to extend the pin  72  outward and a steel cable  73  which is connected between the switch  71  and the pin  72 . As configured, the steel cable  73  links the action of the switch  71  with the pin  72 , so that as the user pulls the switch  71 , the steel cable  73  causes the pin  72  to retract, and as the user ceases to pull the switch  71 , the pin spring causes the pin  72  to extend outward again. When the pin  72  is extended, the pin  72  may engage with the first hole  15   a  or the second hole  15   b , or it may slide along the two-position ROM plate  15 . When the pin  72  is aligned with the first hole  15   a , the guider frame  20  is oriented in the use position. When the pin  72  is aligned with the second hole  15   b,  the guider frame  20  is oriented in the storage position. 
     Looking again at  FIG. 3 , the rotatable crank mechanism  30  is arranged on the rack  12  of the main frame  10  and has a crank shaft  31 , two crank units  32 , a flywheel  33  and a transmission mechanism  34 . The crank shaft  31  is pivotally arranged on the rack  12 . The two crank units  32  are pivotally coupled to the rack  12  and are configured to rotate about the crank shaft  31 . The flywheel  33  is pivotally coupled to the rack  12 . The transmission mechanism  34  is coupled to the crank units  32  and the flywheel  33 . The transmission mechanism  34  further includes a large pulley  35 , a small pulley  36  and a pulley-belt  37 . The large pulley  35  is coaxial to the crank shaft  31  and is fixed to the crank units  32 . The large pulley  35  is also pivotally coupled to the rack  12  and configured to rotate with the crank shaft  31  and the crank units  32 . The small pulley  36  is coaxial with the flywheel  33  and is fixed to the flywheel  33 . The pulley-belt  37  is coupled to the large pulley  35  and the small pulley  36  so that the crank units  32  and the flywheel  33  rotate with each other at a predetermined speed ratio. 
     Each of the two supporting members  40  has a rotating portion  41 , a reciprocating portion  42  and a supporting portion  43 . A front end of each of the two supporting members  40  forms the rotating portion  41  which is pivotally coupled to the crank units  32  and is therefore constrained to move about the circular path. A rear end of each of the two supporting members  40  is pivotally connected to a roller wheel (not numbered) which is slidably supported by the corresponded track  21  and forms the reciprocating portion that can move back and forth along each of the two tracks. In the present embodiment, the supporting portion  43  of each of the two supporting members  40  is arranged between the rotating portion  41  and the reciprocating portion  42 . The reciprocating portion  42  is configured to move along the reciprocating path along the track while the guider frame  20  is oriented in the use position and the rotating portion  41  moves along the circular path. At the same time, the supporting portion  43  moves along the elliptical-like closed path. 
     Each of the two pedals  50  is coupled to the corresponding supporting portion  43  of each of the two supporting members  40 . The pedal  50  is guided by the supporting portion  43  so that the pedal  50  can move along the elliptical-like closed path. 
     In the present embodiment, a front end of each pedal  50  is pivotally coupled to the supporting portion  43 . Moreover, the present embodiment further includes two handle links  80  and two control links  90 . The two handle links  80  are pivotally coupled to the left and right side of the post  13  respectively. Each of the two handle links  80  has a bottom end and a top end. The top end is formed as a handle  81 , and can be swung forth and back during exercise. A rear end of each of the two control links  90  is fixed to the outside of each of the two pedals  50  respectively, and a front end of each of the two control links  90  is pivotally coupled to the bottom end of each of the two handle links  80  respectively. In this embodiment, as the crank units  32  rotate through a full rotation, the supporting portion  43  of each supporting member  40  moves through an elliptical-like closed path, a front end of each pedal  50  moves through an elliptical-like closed path, a rear end of each pedal  50  moves up and down relative to the front end, and each handle link  80  pivots relative to the post  13 . 
     It is worthy to note that the linkage relationship among the supporting members  40 , the pedals  50  and the control links  90  can be modified without changing the basic function of the folding elliptical exercise machine  1 . For instance, the linkage relationship can be changed as disclosed in the U.S. Pat. No. 5,540,637. That is, each of the two control links is directly pivotally connected to each of the two supporting members and each pedal is directly connected to a rear portion of the respective control link. In this configuration, each pedal would be indirectly pivotally coupled to the respective supporting member, and each pedal would still regularly change the angle relative to the corresponding supporting member during exercise. Another possible embodiment may provide the user only a function of leg exercising, i.e. the possible embodiment does not have the handle links  80  and the control links  90 . These and other embodiments would be allowed without changing the scope of this patent. 
     The elliptical exercise machine  1  is configured to be folded up into the storage position as shown in  FIG. 4  and  FIG. 5 , when the elliptical exercise machine  1  is not in use. Generally speaking, the user stands behind the elliptical exercise machine  1  and triggers the switch  71  to retract the pin  72  out of engagement with the first hole  15   a  in the two-position ROM plate  15 . This allows the guider frame  20  to be freely rotated about the guider shaft A 1 . During the folding process, the pin  72  of the pull-pin locking mechanism  70  may slide along the inside face of the two-position ROM plate  15 . As the guider frame  20  is rotated up into the storage position, the pin spring will cause the pin  72  to engage with the second hole  15   b  to lock the guider frame  20  into the storage position. 
     Conversely, the user can unfold the elliptical exercise machine  1  into the use position by unlocking the guider frame  20 . The user triggers the switch  71  to retract the pin  72  out of engagement with the second hole  15   b  while lowering the guider frame  20  into the use position. Once the guider frame  20  rests on the ground surface, the pin  72  will engage with the first hole  15   a  to lock the guider frame  20  in the use position. 
     Additionally, there is a gas spring  24  interconnected between a front end of the guider frame  20  and the main frame  10 . The gas spring  24  can assist the user to lift up the guider frame  20  while folding up into the storage position as well as slow the descending speed to reduce the downward force while folding down into the use position. 
     After the elliptical exercise machine  1  is folded up into the storage position, the present embodiment is configured to position the various linked elements (supporting members  40 , pedals  50 , handle links  80 , handles  81  and control links  90 ) in either the configuration as shown in  FIG. 5  or the opposite configuration as shown in  FIG. 6 , even though the user does not use the locking device  60 . With regard to the movement of the various linked elements of the elliptical exercise machine  1  as they move from the use position to the storage position, the reader can refer to the specification of U.S. Pat. No. 7,946,962. 
     During the folding process, the linked elements are affected by many variables: the last stopped position of the linked elements, the center of gravity of the linked elements, forces applied by the user to the guider frame, and others. Due to the geometry of the linked elements, the position of right and left elements will be opposite to each other. Whatever the displacement process, the elliptical exercise machine  1  will always naturally tend to balance as shown in  FIG. 5  or  FIG. 6  when it is positioned in the storage position. In this balanced state, the handle links  80  are substantially aligned from a lateral view. 
     Referring to  FIGS. 2-5 , the locking device  60  is interconnected between the guider frame  20  and the rotatable crank mechanism  30 . The position of the locking device  60  is affected by the position of the guider frame  20 . The locking device  60  has a spring-loaded latch  61  which is arranged on the rack  12  and can be moved between a locking position and an unlocked position. An elastic member  62  is interconnected between the rack  12  and the spring-loaded latch  61 . In the present embodiment, the elastic member  62  is a tension spring for providing a restoring force to bias the spring-loaded latch  61  to the locking position. 
       FIG. 7  is a detail view of  FIG. 2 .  FIG. 8  is a detail view of  FIG. 4 . As shown in  FIG. 7  and  FIG. 8 , the spring-loaded latch  61  has a hook  61   a  for stopping the large pulley  35  of the rotatable crank mechanism  30 . The present embodiment of the large pulley  35  has two catch portions  63  spaced one hundred and eighty degrees apart from each other on the large pulley  35 . The locations of these two catches cause the crank units  32  to lock into one of two predetermined locations when the spring-loaded latch  61  engages the one of the two catches. 
       FIG. 9A  to  FIG. 9D  are schematic movement diagrams of a locking device while the folding elliptical exercise machine is moved from the use position to the storage position. Referring to  FIG. 9C  and  FIG. 9D , each of the two catch portions  63  has a notch  63   a  and two curved chamfers  63   b  which are positioned on either side of the notch  63   a.  The notch  63   a  and the two curved chamfers  63   b  all protrude past the outer edge of the large pulley  35 . Each of the two catch portions  63  are positioned on the large pulley  35  in such a way that one or the other of the two catch portions  63  will be aligned with the hook  61   a  of the spring-loaded latch  61  when the elliptical exercise machine  1  is folded up into one of the two balanced storage positions as shown in  FIG. 5  and  FIG. 6 . 
     As shown in  FIG. 7  and  FIG. 9A , when the guider frame  20  is oriented in the use position, the front top of the arm  23  is in contact with the spring-loaded latch  61 , thereby rotating the spring-loaded latch  61  counter-clockwise about a hinge shaft A 2 . The spring-loaded latch  61  is oriented in the unlocked position, and does not interfere with the large pulley  35  or either of the catch portions  63 . 
     Referring to  FIG. 9B , when the user triggers the switch  71  to retract the pin  72  out of engagement with the first hole  15   a  and rotates the guider frame  20  up, the arm  23  loses contact with the spring-loaded latch  61  so that the elastic member  62  provides the restoring force to bias the spring-loaded latch  61  from the unlocked position to the locking position. If the catch portion  63  of the large pulley  35  is not aligned with the spring-loaded latch  61 , the hook  61   a  of the spring-loaded latch  61  will approach or slightly touch the surface of the pulley-belt  37  of the large pulley  35  and the rotatable crank mechanism  30  can still rotate. In other words, the spring loaded-latch  61  may be in the locking position, but if one of the two catch portions  63  is not aligned with the spring-loaded latch  61 , then the rotatable crank mechanism  30  is not yet locked in place by the spring-loaded latch  61 . 
     Referring to  FIG. 9C  and  FIG. 9D , during the folding process, the pin  72  may slide along the inside face of the two-position ROM plate  15 . Whether or not the pin  72  engages the second hole  15   b  to lock the guider frame  20  into the storage position, the arm  23  has lost contact with the spring-loaded latch  61 , and the spring-loaded latch  61  is oriented in the locking position. As the larger pulley  35  rotates to a position which nearly aligns the catch portion  63  with the spring-loaded latch  61 , the curved chamfer  63   b  of the catch portion  63  first reaches the hook  61   a  of the spring-loaded latch  61 . Under the guidance and the contact with the curved chamfer  63   b,  the spring-loaded latch  61  will turn counter-clockwise slightly. The catch portion  63  keeps moving until the hook  61   a  slides along the curved chamfer  63   b  and slips into the notch  63   a,  then firmly locks the large pulley  35  into place relative to the spring-loaded latch  61 . Almost at the same time, the pin  72  engages with the second hole  15   b  to lock the guider frame  20  into the storage position. 
     The foregoing locking process is the usual condition of the folding process of the elliptical exercise machine  1 . However, there is another possibility that the guider frame  20  is already oriented and locked in the storage position, but the catch portion  63  of the large pulley  35  is not yet aligned with the spring-loaded latch  61 . In other words, it is possible that the guider frame  20  may be locked in the upright storage position while the rotatable crank mechanism  30  is still free to rotate. In this situation, the user may move the handle link  80  to apply a rotational load to the large pulley  35 , causing it to rotate slightly. This rotation of the large pulley  35  causes one of the two catch portions  63  to be repositioned until it aligns with the hook  61   a  of the spring-loaded latch  61 , causing the spring-loaded latch  61  to engage with the notch  63   a  of the catch portion  63 . Again, the final outcome is that the guider frame  20  is locked into the upright storage position and the rotatable crank mechanism  30  is locked into place relative to the spring-loaded latch  61 . 
     Conversely, it is possible that if one of the catch portions  63  is aligned with the spring-loaded latch  61  before the elliptical exercise machine  1  is folded up into the storage position, the spring-loaded latch  61  will lock the rotatable crank mechanism  30  as soon as the guider frame  20  leaves the use position. In this state, even though the rotatable crank mechanism  30  cannot be rotated, the guider frame  20  can still be rotated up into the storage position. As the guider frame  20  is rotated up, the supporting members  40  are gradually moved vertical until the guider frame  20  is locked into the storage position as shown in  FIG. 5  or  FIG. 6 . Again, the final outcome is that the guider frame  20  is locked into the upright storage position and the rotatable crank mechanism  30  is locked into place relative to the spring-loaded latch  61 . 
     When the user wants to unfold the elliptical exercise machine  1 , the user triggers the switch  71  to retract the pin  72  out of engagement with the second hole  15   b  while lowering the guider frame  20  into the use position. The rotatable crank mechanism  30  will remain locked in place until the guider frame  20  is rotated almost all the way back down into the use position. The spring-loaded latch  61  is not affected by any other force until the front end of the arm  23  comes into contact with the spring-loaded latch  61 , so the hook  61   a  of the spring-loaded latch  61  will continue to engage with the notch  63   a  until it is disengaged by contact with the arm  23 . During the unfolding process, the pin  72  slides along the inside of the two-position ROM plate  15  from the second hole  15   b  until it almost reaches the first hole  15   a.  During this time, the hook  61   a  of the spring-loaded latch  61  is engaging with the notch  63   a  as well. In other words, during the time the guider frame  20  is rotated down from the storage position to the use position, the large pulley  35  is also cannot rotate. When the guider frame  20  is near to the use position, the front end of the arm  23  will first contact with the spring-loaded latch  61  to turn the spring-loaded latch  61  counter-clockwise to the unlocked position. As a result, the hook  61   a  of the spring-loaded latch  61  disengages with the notch  63   a  of the catch portions  63  and the large pulley  35  can be rotated again. 
     The present embodiment makes the ease of use of operation of the equipment the primary consideration. If the large pulley  35  were to be free to rotate during the unfolding process, the user possibly would not be able to control the displacement of those linked elements during the folding or unfolding operations. The present embodiment of the spring-loaded latch  61  automatically disengages the hook  61   a  from the notch  63   a  of the catch portions  63  just as the guider frame  20  is exactly oriented in the use position. 
     It is worthy to note that the position of the spring-loaded latch  61  in the present embodiment is chosen to be the nearest place to the large pulley  35  where it can be engaged directly by the guider frame  20 . Nevertheless, this position is not the only choice. According to the previous descriptions, the balanced storage position of the elliptical exercise machine  1  will be as shown as  FIG. 5  or  FIG. 6 . In another embodiment, the position of the catch portions  63  could remain unchanged, but the spring-loaded latch  61  might be located on a front side of the large pulley  35 , one hundred and eighty degrees relative to the original position, and the spring-loaded latch  61  still can lock the large pulley  35 . The guider frame  20  as it is described would not be able to engage the spring-loaded latch  61  directly, but might need to use other elements like steel cable (the method is similar to the pull-pin locking mechanism  70 ). Additionally, the efficacy of this embodiment is tantamount to the previously cited embodiment. Changing the positions of the two catch portions  63  is also possible so that the designer can change the position of the spring-loaded latch  61  to the top end and bottom end of the large pulley  35  or any other desired positions. One characteristic of the present invention is that the locking device  60  can lock or unlock the rotatable crank mechanism  30  automatically as the guider frame is repositioned from the use position to the storage position or from the storage position to the use position, respectively. For this reason, the position of the spring-loaded latch  61  in the foregoing embodiment is merely one example. 
     It should also be noted that another characteristic of the present invention is locking the rotatable crank mechanism  30  by the locking device  60 , and the present embodiment only describes a device where the locking device  60  locks the large pulley  35 . Because the motion/rotation of the rotatable crank mechanism  30 , the crank units  32 , the flywheel  33 , the large pulley  35 , the small pulley  36 , and the pulley-belt  37  are all interrelated, the locking device  60  locks other elements of the rotatable crank mechanism  30 , and as such, locking any of these interrelated components would have the same effect and would not be departing from the spirit of the present invention. 
     Furthermore, the transmission mechanism  34  of the rotatable crank mechanism  30  for interconnecting between the crank units  32  and the flywheel  33  is “the first drive”, but the transmission mechanism  34  of the present invention also may include “the secondary drive” that is using one belt to interconnect between a crank unit and a secondary driving shaft, then using another belt to interconnect between the secondary driving shaft and a flywheel. If using “the secondary drive”, the locking device can lock a medial pulley which is arranged on the secondary driving shaft as well. 
     More particularly, when the folding exercise machine  1  is folded up into its storage position as shown in  FIG. 5  or  FIG. 6 , the two handle links  80  are substantially aligned. The user can grip both handles  81  which are symmetrical to easily move the folding exercise machine  1  by a roller  16  which is arranged on the base  11 . Furthermore, the guider frame is partially held in the storage position by the force of the gas spring  24 , the guider frame  20  is locked in the upright storage position by the pull-pin locking mechanism  70 , and the rotatable crank mechanism  30  is locked by the locking device  60 , so the folding exercise machine  1  is quite stable in the storage position. Therefore, the user not only can concentrate on moving the folding exercise machine  1 , but need not concern themselves about whether elements will start moving during the transportation of the unit, or to worry about unbalanced torque as the result of moving elements during transportation. 
     Another embodiment involves using a high friction coefficient substance as a spring-loaded latch  61 . When the guider frame  20  is repositioned from the use position to the storage position, the high friction coefficient substance can press on the large pulley  35  and cause the friction to stop the rotation of the large pulley  35 . This method also can achieve the purpose of stopping the large pulley  35 , thereby preventing rotation of the rotatable crank mechanism  30  when the guider frame is oriented in the storage position. 
     According to the aforementioned embodiments, the user can lock or unlock the rotatable crank mechanism  30  automatically while the elliptical exercise machine  1  is folded or unfold without requiring an extra step for locking or unlocking, so that the operation will be very convenient. In addition, the folded elliptical exercise machine  1  is very stable for transportation when the rotatable crank mechanism  30  is locked. Moreover, the aligned handle links  80  and handles  81  can further aid in the convenience of transporting the elliptical exercise machine  1  when it is folded up into the storage position. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.