Abstract:
A handle assembly of luggage comprised of a handle grip with a push button, two first sliding tubes, at least one pair of second sliding tubes, two supporting tubes, two first locking devices, each provided below each first sliding tube, at least one pair of second locking devices, each provided below each second sliding tube, a pair of first connecting means attached between the handle grip and the first locking devices, and at least one pair of the second connecting means for controlling the second locking devices. The length of the fully extended handle is expected to be longer than the height of the luggage body so as to provide the user with a luggage handle which can be extended to a sufficient height to meet the user&#39;s various towing needs.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    Reference is made to pending application (Attorney Docket No. 890.003.018), entitled LOCKING DEVICE WITH IMPROVED JUMPING MEANS FOR RETRACTABLE HANDLE OF LUGGAGE, assigned to the assignee of this application and filed on even date herewith.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a retractable handle of luggage and more particularly to a locking device for a retractable handle of luggage.  
           [0004]    2. Description of Related Art  
           [0005]    Conventionally, a retractable luggage handle uses a single-stroke locking device and is equipped with only one locking device to control the luggage handle&#39;s movement. This one locking device is usually installed at the bottom of a single sliding tube and is provided as a medium element between the one sliding tube and a supporting tube. However, it is possible to design the locking device&#39;s sliding tube in such a manner that the engagement between the sliding tube and the supporting tube is done through a plurality of retaining slots provided on the supporting tube. As a result, more height options are created for the retractable handle. Conventionally, the length of an extendable luggage handle, which precedes the full height of an upright luggage should be no taller than the height of the luggage case itself. Warsaw Convention also stipulates the permissible maximum dimensions for carry-on luggage. Therefore, the total bulk height of an upright luggage body, plus the extra height spanned by a fully extended luggage handle, should still be shorter than the straight-line distance measured from the draping fingertips of a naturally-posed, standing individual to the ground. This means that the user is often urged to bend his/her back to reach the luggage handle in order to get hold of the luggage. It is obvious that the conventional design is not a handy design for most users.  
           [0006]    Moreover, in order for the user to move his/her luggage in and out of luggage storage areas inside an airplane or an automobile, the user often needs to retract the handle to its lowest position to perform a smooth loading task. Since, in the conventional design, there is only one retraction stroke provided on the locking device of the luggage handle, the lowest position of the handle grip also means the closure of the sliding tube to the supporting tube of the luggage handle. That is to say, no allowance is ever given between the user&#39;s handhold position and the luggage body when the user is trying to partially retract the handle and move it to the luggage storage space in a transportation vehicle. Such a luggage handle&#39;s on-the-run positioning leads to an unfavorable physical placement of the luggage body, which in turn causes the center line of the luggage handle grip to be tilted away from the center line of the luggage body when the luggage is lifted. In other words, the lower portion of the luggage will come nearer to the user than the top portion thereof. Thus, the unfavorable physical position of a dangling piece of luggage interferes with the user&#39;s physical movement.  
         SUMMARY OF THE INVENTION  
         [0007]    It is therefore an objective of the present invention to produce a multi-stroke locking device for the retractable handle of a luggage piece in order to minimize the problems which were encountered in the prior art.  
           [0008]    Another objective of the present invention is to produce a locking device for the retractable handle of a luggage piece, wherein the mechanical structure of the new locking device is generally simplified so as to effect a quick assembly in the manufacturing process.  
           [0009]    It is still another objective of the present invention to produce a locking device for the retractable handle of a luggage piece, wherein the handle grip can be raised a small distance in height from its bezel recess located on top of the luggage and also be locked there so as to be used as a carry-on handle for the luggage for the possibility of tilting when it is lifted. Consequently, such a new design will improve the luggage&#39;s balance when the user is attempting to use as a carry-on handle.  
           [0010]    To achieve the above mentioned and other objectives, the present invention embodies a handle system for the luggage which comprises two symmetrically identical portions, each having a handle grip and a push button thereon, a first sliding tube affixed to the end of the handle grip, a first locking device detachably attached to the bottom of the first sliding tube, a second sliding tube with a plurality of holes drilled upon it for allowing the first sliding tube to glide freely therein, a second locking device detachably attached to the bottom of the second sliding tube, a supporting tube with a plurality of holes drilled upon it for allowing the second sliding tube to glide freely therein, and a first connecting means linked between the push button and the first locking device; wherein the second locking device comprises an upper portion, a lower portion, a sliding block longitudinally slidable within the upper portion, a spring laterally biased in the lower portion, a locking block laterally slidable within the lower portion, and a second connecting means having the top end clung to the first locking device and the bottom end clung to the longitudinally allocated sliding block.  
           [0011]    The above and other objectives, features, and advantages of the present invention will become apparent from the following detailed description made in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is an exploded view of a preferred embodiment of a locking device for the retractable handle of luggage according to the invention;  
         [0013]    [0013]FIGS. 2A and 2B are first and second sectional views showing the retracted positions of the fully retracted handle, respectively;  
         [0014]    [0014]FIGS. 3A and 3B are similar to FIGS. 2A and 2B, respectively, where the push button is pressed to cause the handle grip to be pulled up a small distance from the bezel recess located on top of the luggage and be fixedly locked thereat;  
         [0015]    [0015]FIGS. 4A and 4B are similar to FIGS. 3A and 3B, respectively, where the push button is again pressed to cause the handle grip to be pulled up again so that the first locking device is locked into the upper hole of the second sliding tube and the second locking device is locked into the lower hole of the supporting tube;  
         [0016]    [0016]FIGS. 5A and 5B are similar to FIGS. 4A and 4B, respectively, where the push button is pressed again to cause the handle grip to be further pulled up so that the first locking device is cleared from the upper hole of the second sliding tube, and the second locking device is moved up;  
         [0017]    [0017]FIGS. 6A and 6B are similar to FIGS. 5A and 5B, respectively, where the second locking device is locked into the upper hole of the supporting tube so as to pull the second locking device in an extension position, and the first locking device is pull by the steel cable and retracted into the second sliding tube;  
         [0018]    [0018]FIGS. 7A and 7B are similar to FIGS. 6A and 6B respectively, where the handle is fully extended and locked; and  
         [0019]    [0019]FIGS. 8A and 8B are similar to FIGS. 7A and 7B, respectively, where the first locking device is retracted into the second sliding tube by pressing the push button so that the bottom of the first locking device is engaged with the top of the second locking device, wherein the lock pin of the second locking device is not fully extended such that the second locking device is suppressed by the first locking device to clear the second locking device from the upper hole of the supporting tube. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    [0020]FIG. 1 shows a multi-stroke locking device for the retractable handle of a luggage piece constructed in accordance with the present invention, wherein the handle system is provided at the back of the luggage with a handle grip retractable to a recess located on top of the luggage.  
         [0021]    Note that since the present handle assembly is bilaterally symmetric, the description on one side of the handle system serves to speak for both the entities. The handle system of the present invention comprises a first sliding tube  10 , a first locking device  20 , a first sleeve member  30 , a second sliding tube  40 , a second locking device  50 , a second sleeve member  60 , and a supporting tube  70 . The first sliding tube  10  has a lower hole  13  and an upper hole  12 ; the upper hole  12  is connected to the receiving opening on one side of the handle grip (not shown) by a known fastener. The first locking device  20  is detachably attached to the bottom of the first sliding tube  10 . The second sliding tube  40  is provided to allow the first sliding tube  10  to glide freely therein and contains the top, middle, and lower holes  45 ,  46 , and  47  on a first side, two apertures  42  on the first and third sides, and two pin holes  43  on a second and fourth side. The first sleeve member  30  is fitted to the top of the second sliding tube  40  and has two slightly protruded projections  32  located at the two opposite sides of the sleeve member&#39;s  30  outer surface; the two projections  32  are provided to couple with the two apertures  42  of the second sliding tube  40 . The second locking device  50  is detachably attached to the bottom of the second sliding tube  40  and is secured to the second sliding tube  40  by a pin  44 . The supporting tube  70  is provided to allow the second sliding tube  40  to glide freely therein; the supporting tube  70  contains the top and lower holes  73  and  74  on a first side, two apertures  72  on the first and third sides, and two pin holes  75  symmetrically sited on the first and third sides, while one is below the lower hole  74 . The second sleeve member  60  is installed on the top of the supporting tube  70  and has two slightly protruded projections  62  located at the two opposite sides of the sleeve member&#39;s  60  outer surface; the two projections  62  are provided to couple with the two apertures  72  on the upper part of the supporting tube  70 .  
         [0022]    The first locking device  20  comprises a first housing  21 , a first connecting means  22 , a helical spring  23 , and a first locking block  24 . The first housing  21  contains an upper portion  210  and a lower portion  214 . The upper portion  210  consists of a longitudinal guide groove  212 , a longitudinal retaining groove  211 , and a laterally traversed pin hole  213  such that the pin  14  may be inserted through the lower holes  13  of the first sliding tube  10  and the pin hole  213  to secure the first locking device  20  to the first sliding tube  10 . The lower portion  214  contains a lateral tunnel cavity  215  and a smoothly curved portion  218  (see FIGS.  2 A- 7 A). The helical spring  23  is laterally provided inside the tunnel opening  215  at the bottom of the first housing  21  to be biased against the first locking block  24  for completing the operation of locking or unlocking it. The first locking block  24  is provided to be inserted into the lateral cavity  215  within the lower part of the first housing  21  and contains a projection  240  on a first side, an aperture  241  on a second side, and an opening  245  which is in communication with the side aperture  241 . The first connecting means  22 , in the form of a curvilinearly deformable steel cable, has two enlargements provided at the two ends. One end of the enlargements (not shown) is secured to the handle grip  90 , and the other end  221  is secured into the hollow opening  245  on the first locking block  24  through a path, which starts from the longitudinal retaining groove  211 , the smoothly curved portion  218 , the lateral cavity  215 , and reaches the hollow opening  245  of the first locking block  24  such that the mere pressing of the push button  91  on the handle grip  90  may actuate the first locking device  20  through the movement of the steel cable  22 .  
         [0023]    The second locking device  50  is formed by a second locking housing  50 A, which has an upper portion  51  and a lower portion  52 . The upper portion  51  contains a longitudinal groove  511  and two laterally traversed pin holes  512  (these two pin holes serve as the two opening mouths of the laterally penetrated pin tunnel) such that the pin  44  may be inserted through the lower hole  43  of the second sliding tube  40  and the pin holes  512  to secure the second locking device  50  and the second sliding tube  40  together. The lower portion  52  consists of a laterally allocated central dent  521 , a circular indentation  523  opened at the walled end of the central dent  521 , a helical spring  53 , a generally cubic shaped locking block  54 , a longitudinal sliding block  55 , and a second connecting means  56 . The helical spring  53  is horizontally placed into the laterally disposed central dent  521  at the lower portion  52  of the second housing  50 A and has one end biased against the circular indentation  523  on the walled end of the central dent  521 . The generally cubic shaped locking block  54  goes against the helical spring&#39;s  53  other end and is horizontally slidable within the central dent  521  at the lower portion  52  of the second locking housing  50 A. With one end biased against the helical spring  53 , the locking block  54  contains a frontal lock pin  541  and two triangular projections  542  symmetrically provided at the two opposing board sides of the locking block&#39;s  54  outer surface. The lock pin  541  is to go into the lower portion  553  of the longitudinal sliding block  55  to facilitate the coupling operation between the two triangular projections  542  and the two V-shaped recesses  555  of the lower portion  553  of the sliding block  55 ; each of the two triangular projections  542  has a lower slope  5421  and an upper slope  5422 .  
         [0024]    The sliding block  55  is longitudinally slidable along the groove  511  of the upper portion  51  of the second locking housing  50 A and during sliding, the sliding block  55  glides itself through the mouth of the horizontally disposed central dent  521  of the lower portion  52  of the second locking housing  50 A. The sliding block  55  has an upper portion  551  and a lower portion  553 . The upper portion  551  has a protruded groove  552  on top and a longitudinal tracking surface below it. The lower portion  553  has a side profile wider than the upper portion  551  and contains a longitudinally deployed rectangular recess  557  and two V-shaped recesses  555 . The rectangular recess  557  is provided to communicate with the upper portion  551 , and the two V-shaped recesses  555  are located on the two opposite sides of the sliding block&#39;s  55  outer surface; each of the two V-shaped recess  555  has an upper slope  554  and a lower slope  556 . The second connecting means  56 , in the form of a slim rigid metal section, has a top hook end  561  clung to the guide groove  212  of the first housing  21  of the first locking device  20  and a bottom hook end  562  clung to the arch-shaped hook receiver  552  on the upper portion  551  of the sliding block  55 .  
         [0025]    The following narrative is a description of the operation procedure for the handle system of the present invention. To provide a proper setting to accommodate the forthcoming discussion, the luggage handle&#39;s locking device is initially assumed to be at its dormant retracted position. By making references to the adjoined illustrations FIGS.  2 A- 8 A, the following narrative can be best understood.  
         [0026]    Originally, when the push button  91  is not pressed by the user, the handle  90  is at its recessed position (see FIGS. 2A and 2B). At this stage, the first sliding tube  10  is retracted into the second sliding tube  40  and the second sliding tube  40  is retracted into the supporting tube  70 . While the retraction of the first sliding tube  10  into the second sliding tube  40  is accomplished because the projection  240  of the locking block  24  is biased by the spring  23  to engage with the lower hole  47  of the second sliding tube  40 , the retraction of the second sliding tube  40  into the supporting tube  70  is achieved because the bottom of the first locking device  20  is biased against the top of the sliding block  55  of the second locking device  50  and thus incurs the first end  5411  of the lock pin  541  of the locking block  54  (see FIG. 2A) to engage with the lower hole  74  of the supporting tube  70 . Thus, the luggage handle is locked at its retracted position. However, the engagement of the locking pin  541  to the lower hole  74  of the supporting tube  70 , unlike the engagement of the guide pin  240  to the lower hole  47  of the second sliding tube  40 , does not mean the handle is fully locked. The reason for this is that, at the initial stage of the locking device, i.e., when neither the first nor the second sliding tube is protracted, the bottom of the first locking device  20  is biased against the top of the longitudinal sliding block  55  of the second locking device  50  and thus pushes it down to descend over the exact mating position which leads to a full locking of the lock pin  541  provided on the locking block  54 . Therefore, only the first end  5411  of the lock pin  541  of the locking block  54  is induced to engage with the lower hole  74  of the supporting tube  70 .  
         [0027]    When the push button  91  is first pressed down by the user, as shown in FIGS.  3 A- 3 B, the cable  22  is instantly strained to move upward to induce compression force to the spring  23 , displace the locking block  24 , and withdraw the guide pin  240  from its initial position at the lower hole  47 . This is the disengagement action of the projected guide pin  240  on the locking block  24  from the lower hole  47  of the second sliding tube  40 . The handle is then pulled up by the user to cause the locking block  24 , now disengaged from the hole  47 , to begin to move from its original position at the lower hole  47  to a second position at the center hole  46  on the second sliding tube  40  (see FIG. 3A). The first locking device  20  is therefore relocated to a new elevated position. Concurrently, the user&#39;s grasp of the handle grip  90  and raising of the first sliding tube  10  causes the lateral locking block  54  to be fully engaged into the lower hole  74  of the supporting tube  70 . When the user pulls up the first sliding tube  10 , the bottom of the first locking device  20  is separated from the top of the second locking device  50 . Since, at this moment, the top of the sliding block  55  is no longer biased by the bottom of the first locking device  20 , and the sliding block  55  itself is vertically slidable on the second locking device  50  in the first place, the incurred ascent of the sliding block  55  causes the locking block  54  to be pushed to the further right direction (see the right half of FIG. 1) by the expansion of the horizontally deployed spring  53  and thus induces the lock pin  541  of the locking block  54  to be fully extended. In other words, the bottom face  5412  of the lock pin  541  is fully extended to lock itself in place to the lower hole  74  of the supporting tube  70 . In such a manner, the locking block  54  is entirely locked into the lower hole  74  of the supporting tube  70 , and the second sliding tube  40  is also thus fixedly secured in place. At this time, the upper slopes  5422  of the triangular projections  542  are closely engaged to the upper slope  554  of the sliding block  55  (see the left half of FIG. 1).  
         [0028]    Up to this point, if the user chooses to release the push button  91  when the locking block&#39;s  24  guide pin  240  reaches the center hole  46  of the second sliding tube  40 , then followed by the secured allocation of the second sliding tube  40  on the supporting tube  70 , the first sliding tube  10  is also relocated when the locking block&#39;s  24  guide pin is engaged into the center hole  46  of the second sliding tube (see FIGS.  3 A and  3 B); this accomplishes the retractable luggage handle locking device&#39;s first protraction height option. In this manner, a unique purpose of carry-on handle for luggage piece of the present invention is thus attained. However, at this time, if the user chooses to keep on pressing the push button  91  and continues to pull up the first sliding tube  10  when the locking block  24  slips over the center hole  46  of the second sliding tube  40 , then the first sliding tube  10  keeps on gliding upward until the locking block&#39;s  24  guide pin  240  reaches the top hole  45 . Here again, the user has two choices: if the user chooses to release the push button  91 , then the first sliding tube  10  is once more relocated to its second height position when the locking block&#39;s  24  guide pin  240  is engaged into the top hole  45  (see FIGS.  4 A and  4 B); this accomplishes the retractable luggage handle locking device&#39;s second protraction height option. However, if the user chooses to keep on pressing the push button  91  and continues to pull up the first sliding tube  10  when the locking block  24  slips over the top hole  45  of the second sliding tube  40 , then the first sliding tube  10  keeps on gliding upward until the longitudinal sliding block  55  of the second locking device  50  is incurred to move upward. Sometime after the locking block  24  (presently retracted due to the pressing of the push button  91 ) slips over the top hole  45  on the second sliding tube  40  and before the moment when the top edge of the first locking device&#39;s  20  lower portion  214  reaches the bottom end of the first sleeve member  30  and is stopped thereat, the second connecting means&#39;  56  top hook end  561  comes into engagement with the upper platform of the first locking device  20 . Since the escalating distance the first locking device  20  travels during this very short time period between the two engaging instants, when the locking block&#39;s  24  guide pin  240  passes through the top hole  45  of the second sliding tube  40  and when the second connecting means&#39;  56  top hook end  561  hits the upper platform of the first locking device  20  may present a great significance in the forthcoming discussion, it is therefore denoted here as the distance DELTA1. Since the second connecting means  56  is a slim rigid metal section with a bottom hook end  562  clung to the arch-shaped hook receiver  552  on the upper portion  551  of the sliding block  55 , and also because there is a small distance left between the contacting spot of the first locking device  20  and the second connecting means  56  and the clashing position of the first locking device  20  and the first sleeve member  30 , the sliding block  55  will move upward a small distance if the user keeps on lifting the first sliding tube  10  until the lifting action is stopped by the mutual engagement of the first locking device  20  and the first sleeve member  30 . The lifting span of the sliding block  55  from its initial standstill position to its later modestly lifted position exactly equals the distance between the locus of the top edge of the first locking device&#39;s  20  lower portion  214  when the first locking device  20  hits the second connecting means  56  at their tops and the bottom end position of the first sleeve member  30  at that same instant. Since this distance may also present great significance in our forthcoming discussion, it is hereby represented as the distance DELTA2.  
         [0029]    The sliding block&#39;s  55  lifting reaction also causes the second end  5412  of the lock pin  541  of the second locking device  50  to move to the right to unlock itself from the lower hole  74  of the supporting tube  70  (see FIGS. 5A and 5B). Since the user&#39;s first pressing of the push button  91  on top of the luggage handle  90 , the second sliding tube  40 , even though originally not completely locked inside the supporting tube  70  due to the initial semi-engagement of the lock pin  541  to the tube&#39;s lower hole  74 , has always remained at the same lowermost position inside the supporting tube  70 . However, with the relief of the lock pin  541  in the second locking device  50  from the lower hole  74  of the supporting tube  70 , the second sliding tube  40  now also becomes maneuverable. At this time, however, if the user chooses to further pull up the luggage handle, since the top edge of the first locking device&#39;s  20  lower portion  214  is momentarily clashed with the bottom end of the first sleeve member  30  and is stopped thereat (i.e., the first locking device  20  and the first sliding tube  10  both have reached their highest stretching limit), the first sliding tube  10  and the second sliding tube  40  together will move upward until the locking block  54  of the second locking device  50  comes into engagement with the top hole  73  of the supporting tube  70  and locks itself therein (see FIGS. 6A and 6B). Within this stage of the locking device&#39;s movement (i.e., the resulting effect of the user&#39;s sole manual action of continuously lifting the luggage&#39;s handle grip), before the lock pin  541  of the locking block  54  enters the upper hole  73  of the supporting tube  70 , the coupled action of the first sliding tube  10  and the second sliding tube  40  contains several important features which later prove to be very useful for the handle locking mechanism&#39;s follow-up movement. After the relief of the lock pin  541  of the second locking device  50  from the lower hole  74  of the supporting tube  70  and the subsequent physical collision between the top edge of the first locking device&#39;s  20  lower portion  214  and the bottom end of the first sleeve member  30 , the first sliding tube  10  moves upward along with the second sliding tube  40  with no mutual relative motion, and the frontal head of the locking pin  541  is forced to lean against the inner wall of the supporting tube  70  and with its other end severely biased by the compressed helical spring  53  when the second locking device  50  along with the second sliding tube  40  is being pulled up. This suggests that the upward displacement of the longitudinal sliding tube  55  w.r.t. the main body of the second locking device  50 , although initially enacted by the upward dragging force evolved from the elevation of the first locking device  20  and the incurred tension of the rigid second connecting means  56 , is not now induced by the dragging force passed from the top end of the second connecting means  56  but by the constant withdrawal of the locking block  54  of the second locking device  50 , during which time the rigid second connecting means  56  is not strained. Throughout this entire period, if viewed from the side, the lower slope  5421  of the locking block&#39;s  54  triangular shaped side protrusion leans against the lower slope  556  of the triangular shaped indentation provided at the lower portion  553  of the longitudinal sliding tube  55 , which also means the locking block  54  of the second locking device  50  is squeezed by the spring  53  and confined inside the very limited cross sectional space of the supporting tube  70 .  
         [0030]    However, once the frontal head of the locking pin  541  of the locking block  54  meets an opening (in this case, the opening is the top hole  73  of the supporting tube  70 ), the suppressed locking block  54 , pushed by the compressed helical spring  53 , will instantly move toward the opening and exit the top hole  73  as far as the limiting frame behind the lock pin  541  allows. During this process, the longitudinal sliding block  55  will descend to its initial non-displaced position w.r.t. the main body of the second locking device  50 , and if again viewed from the side, the locking block&#39;s  54  triangular shaped two protrusion sides  5422  and  5421  now match precisely with the upper and lower sides  554  and  556 , respectively, of the triangle shaped indentation provided at the lower portion  553  of the longitudinal sliding tube  55 . Up to this point, followed by the engagement of the lock pin  541  of the locking block  54  to the upper hole  73  of the supporting tube  70 , a small distance DELTA2 (as defined earlier in the discussion), which originally was lifted for the purpose of retracting the locking block  54  of the second locking device  50  from the lower hole  74  on the supporting tube  70 , now is lowered again to accommodate a smooth protraction of the lock pin  541  of the locking block  54  from the upper hole  73  of the supporting tube  70 . Nevertheless, remember that before the actual occurrence of the lifting action of the small distance DELTA2, another small distance ascent DELTA1 was also lifted by the user; that elevation was for allowing the second connecting means&#39;  56  top hook end  561  to contact the upper platform of the first locking device  20  sometime after the locking block&#39;s  24  guide pin  240  slips over the top hole  45  of the second sliding tube  40 . Perceivably, the engagement of the locking block  54  of the second locking device  50  to the top hole  73  of the supporting tube  70  does not guarantee another engagement of the first locking device&#39;s  20  locking block  24  to the top hole  45  of the second sliding tube  40 . By studying the relative positions among the first locking device  20 , the first sleeve  30 , and the engagement holes&#39;  47 ,  46 , and  45  respective loci on the second sliding tube  40 , after the engagement of the locking block  54  of the second locking device  50  to the top hole  73  of the supporting tube  70 , there is still another small distance DELTA1 which needs to be descended by the first sliding tube  10  to facilitate a second engagement of the first locking device&#39;s  20  locking block  24  to the top hole  45  of the second sliding tube  40  (see FIGS. 6A and 6B).  
         [0031]    The descent of the longitudinal sliding block  55  to its original non-displaced position on the second locking device  50  does not incur a whole bulk descent of the second locking device  50 , yet the longitudinal small drop of the sliding block  55  does incur a sudden descent of the first locking device  20  through the actuation of a downward dragging force induced by the second connecting means&#39;  56  descent (because the second connecting means&#39;  56  bottom hook end  562  is clung to the longitudinal sliding block&#39;s  55  arch-shaped hook receiver  552  and its top hook end  561  is clung to the top of the first locking device  20 ). Although the downward action of the first locking device  20  is only affected by the second connecting means&#39;  56  top hook end&#39;s  561  downward dragging force when the second connecting means&#39;  56  top hook end  561  is in contact with the top platform of the first locking device  20 , yet the momentum evolved from the sudden descent of the first locking device  20  continues on even after the separation of the first locking device  20  from the second connecting means  56  and this momentum-related inertia further moves the first locking device  20  downward until the locking block&#39;s  24  guide pin  240  reaches the second sliding tube&#39;s  40  top engagement hole  45 . At this time, since the push button is not pressed, the first connecting means  22  is therefore not activated, and the release of the locking block  24  out of the second sliding tube&#39;s  40  top engagement hole  45  from the sudden expansion of the compressed helical spring  23  is not in any way obstructed. As a result, the needed descent of another small distance DELTA1 of the first sliding tube  10 , a smooth protraction of the locking block&#39;s  24  guide pin  240  at the top hole  45  of the second sliding tube  40 , and the retractable luggage handle locking device&#39;s third protraction height option are all accomplished (see FIGS. 7A and 7B). When the luggage handle is placed in a fully extended position, owing to the locking device&#39;s multi-stroke design feature, it can accommodate even the tallest user, allowing them to tow the luggage in considerable comfort.  
         [0032]    The following is a description of the luggage handle&#39;s retraction operation. The luggage handle&#39;s locking device momentarily is assigned to be at its initial highest protracted position (see FIGS. 7A and 7B), and the luggage&#39;s push button stays as non-depressed. When the user presses the push button, however, the first connecting means  22  is strained and pulled up. Since the first connecting means  22  is in the form of a curvilinearly deformable steel cable, the first connecting means  22  ascending action causes the guide pin  240  of the horizontally allocated locking block  24  to retract from the top hole  45  of the second sliding tube  40  and thus releases the first sliding tube  10  from its protractedly locked position. A ground is given to the user to further push down the first sliding tube  10  and retract it into the second sliding tube  40 . This further lowering operation of the first sliding tube  10  causes the guide pin  240  of the horizontally-allocated locking block  24  to slip through the center hole  46  of the second sliding tube  40  while the lock pin  541  on the locking block  54  is still protractedly secured to the upper engagement hole  73  of the supporting tube  70 . At this time, if the user chooses to release the push button, the guide pin  240  is immediately launched by the compressed spring  23  and comes out of the center hole  46  of the second sliding tube, which accomplishes the retractable luggage handle locking device&#39;s fourth protraction height option. Since the reaction is a lowering operation for the first sliding tube  10 , the luggage handle&#39;s fourth height option is uprightly shorter than its third height option but is taller than the second height option. However, if the user chooses to continue pressing the handle&#39;s button and meanwhile pushes further down the first sliding tube  10 , the guide pin  240  of the horizontally allocated locking block  24  slips over the center hole  46  of the second sliding tube  40  and continues to descend while the lock pin  541  on the locking block  54  is still protruded at the upper hole  73  of the supporting tube  70 . At this time, the bottom of the first locking device  20  comes into contact with the top of the sliding block  55 . The lower portion  214  of the first locking device  20  then pushes down the top of the sliding block  55  to cause the upper slopes  554  of the sliding block  55  to press against the upper slopes  5422  of the triangular projections  542 , thus pulling in the lock pin  541  of the second locking device  50  from the upper hole  73  of the supporting tube  70 . With the release of the engagement pin  541  from the upper hole  73  of the supporting tube  70 , the second sliding tube  40  is free to be retracted into the supporting tube  70 , and if the user chooses to push down the first sliding tube  10  and the second sliding tube  40  all the way down to their respective lower hole positions, the locking device eventually returns to its initial fully retracted location (as seen in FIGS. 2A and 2B). Thus, the cycle of the protraction-retraction operation is completed.  
         [0033]    In the preferred embodiment the first locking device  20  is a primary component and the second locking device  50  is a supplementary component in the luggage handle&#39;s locking mechanism. Thus in other embodiments, the number of the second locking devices  50  and the number of the second sliding tubes  40  may be increased. As a result, it is possible to produce luggage handle systems having a plurality of constituent tubes along with their adjoining locking devices, resulting in a great variety of luggage handle protraction heights.  
         [0034]    Note that the provision of the cable  56  and the center hole  46  of the second sliding tube  40  may be omitted if the design requirement does not include the pre-assigned first protraction height of the luggage handle, which is a small lifting length that allows the luggage handle to be extended a small distance on top of the luggage body to accommodate the smooth undertaking of a minor loading situation.  
         [0035]    Also note that the length of the elongated upper portion  210  of the first locking device  20  is designed to be longer than the length of the first sleeve member  30 . This is especially designed to strengthen the connection between the first sliding tube  10  and the second sliding tube  40 , because often this spot turns out to be the Achilles&#39; heel for luggage handle design.  
         [0036]    It is important to note that the most crucial innovation in the present invention is with the second locking device  50 . If, for example, the second locking device  50  is not provided, then, in order to maintain the multi-stroke handle system&#39;s normal function, another locking device very similar to the present first locking device  20  may have to be employed instead. With the addition of another locking device  20  to replace the present second locking device  50 , not only must the handle system include two independent control chains fitted into one tiny space, but also the user may have to press the two separate control buttons twice to achieve the luggage handle&#39;s protraction-retraction operation. By using such a design, the luggage handle&#39;s locking mechanism becomes clumsy, complicated, and easy to malfunction. In the preferred embodiment, the second locking device  50  is simplified to comprise only the two housings  51  and  52 , one horizontally allocated spring  53 , one horizontally deployed locking block  54 , a longitudinal sliding block  55 , and a second connecting means  56 . Amongst them, the uprightly located sliding block  55 , the lateral locking block  54 , and the second connecting means  56  (perhaps in the form of a slim rigid metal section) are actually the three threshold elements within the second locking device  50 . As stated above, the upper and the lower slopes  5421  and  5422  of the locking block  54  engage, respectively, against the upper slope  554  and the lower slope  556  of the sliding block  55 . Also, with the top and the bottom hook ends  561  and  562  of the second connecting means  56  attached, respectively, to the guide groove  212  on the first housing  21  and the protruded groove  552  on the upper portion  551  of the sliding block  55 , the locking functions as described above are accomplished.  
         [0037]    While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.