Abstract:
A traveling and accelerating system for bicycles includes a frame having a front wheel at a front part and a rear wheel at a rear part thereof; a pair of pedals fixed at both sides of a shaft which is rotatably supported at a boss being fixed under a center of the frame, to be driven by a user&#39;s feet; a driving sprocket axially fixed on the shaft for transmitting rotation power via a chain to the rear wheel; a housing attached at one side of the boss to be closed with a cap and having a hollow cross-sectional shape to accommodate accessories; a pinion axially fixed on the shaft beside the driving sprocket in the housing; a first gear member accommodated in the housing and having an inner gear part along its inner diameter; a second gear member movably contacting the first gear member and provided with planetary gears to be engaged with the inner gear part of the first gear, the planetary gears being fixed by pins and rotatable in relation to the pins; a pair of latch means respectively inserted and fixed in the first gear member and the second gear member by being penetrated with a shaft of the pedals so as to rotate the gear members respectively in one direction; and a conversion control part connected to a release cable outside the housing for setting a travel mode or an acceleration mode corresponding to rotation directions of the pedals by controlling engagement of the first gear member and the second gear member according to the user&#39;s selection.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a traveling and accelerating system for bicycles, and more particularly to, an improved traveling and accelerating system for bicycles by which the bicycle may travel forward regardless of rotation direction of pedals and accelerated travel is also possible without changing gears. 
     2. Description of the Prior Art 
     In general, bicycles include front and rear wheels, pedals to generate power by being stepped by a user, and a power transmission means to transfer the power generated by rotation of the pedals to the rear wheel. 
     The power transmission means includes a driving sprocket mounted at the pedals, a driven sprocket having a latch for transmitting power toward the rear wheel in one direction, and a chain to connect the driving sprocket to the driven sprocket. 
     The driven sprocket is provided with a latch member to be engaged with the rear wheel only in one direction. 
     As described above, the conventional bicycle travels only in one direction, that is, in the forward direction by rotation power which is generated by rotating the pedals forward and transmitted through the chain connecting the driving sprocket to the driven sprocket. 
     Therefore, the user has to rotate the pedals only in the forward direction, and such a same movement makes the user&#39;s leg-muscles unbalanced and makes the user feel bored and tired easily, while it is impossible to relieve his fatigue while riding the bicycle. 
     In the conventional traveling device, even though it is possible to stop rotation of the pedals or rotate the driving sprocket and the chain reversely in response to reverse rotation of the pedals, the power is cut off and not transmitted by a forward latch means provided inside the driven sprocket so that the driven sprocket races. 
     In order to resolve the above disadvantages, Korean Patent Publication No. 95-13589 has suggested a reverse traveling device which includes a forward clutch to alternatively transmit driving power to a driving sprocket, a feed shaft of which engagement state is changeable by means of an operation lever, an idle gear and a reversing gear wheel, so that the bicycle may travel forward even in case of backward rotation of the pedals, developing the user&#39;s feet and legs in balance. 
     The reverse traveling device has, however, still problems that the structure thereof is too complicated and this reverse traveling device cannot be adapted to the driving wheel at the driven sprocket side of the currently widespread bicycles, so that a new bicycle should be purchased. 
     Furthermore, such a proposed reverse traveling device has no change gear, so that there is a tendency to avoid use of it. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a traveling and accelerating system for bicycles which may transmit power in case of not only forward rotation but also backward rotation of pedals. 
     It is another object of the present invention to provide a traveling and accelerating system for bicycles which may operate in both forward and backward directions of pedal rotation so that users may develop their leg-muscles in balance without feeling as bored and tired as riding the prior art bicycle. 
     It is a further object of the present invention to provide a traveling and accelerating system for bicycles which is provided with a change gear integrally for accelerated traveling so that an additional change gear is not necessary any more and users may purchase a bicycle at a relatively low cost. 
     To achieve the above objects, the present invention is directed to a traveling and accelerating system for bicycles which includes a frame having a front wheel at a front part and a rear wheel at a rear part thereof; a pair of pedals fixed at both sides of a shaft which is rotatably supported at a boss being fixed under a center of the frame, to be driven by a user&#39;s feet; a driving sprocket axially fixed on the shaft for transmitting rotation power via a chain to the rear wheel; a housing attached at one side of the boss to be closed with a cap and having a hollow cross-sectional shape to accommodate accessories; a pinion axially fixed on the shaft beside the driving sprocket in the housing; a first gear member accommodated in the housing and having an inner gear part along its inner diameter; a second gear member movably contacting the first gear member and provided with planetary gears to be engaged with the inner gear part of the first gear, the planetary gears being fixed by pins and rotatable in relation to the pins; a pair of latch means respectively inserted and fixed in the first gear member and the second gear member by being penetrated with a shaft of the pedals so as to rotate the gear members respectively in one direction; and a conversion control part connected to a release cable outside the housing for setting a travel mode or an acceleration mode corresponding to rotation directions of the pedals by controlling engagement of the first gear member and the second gear member according to the user&#39;s selection. 
     According to the traveling and accelerating system for bicycles of the present invention, the user may simply change the pedals&#39; rotation direction forward and backward by operating the conversion lever while keeping forward traveling of the bicycle, thereby promoting balanced development of leg-muscles. 
     Also, it becomes possible to selectively accelerate traveling speed by increasing rotation number with relation to a certain rotation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is a disassembled perspective view showing the construction of principal parts of a traveling and accelerating system for bicycles according to the present invention; 
     FIG. 2 is a partially taken unfolded view showing the construction of the traveling and accelerating system for bicycles according to the present invention, which is in an assembled state; 
     FIG. 3 is a partially taken unfolded operational view for explaining forward normal travel mode in case of stepping pedals forward; 
     FIG. 4 is a partially taken unfolded operational view for explaining accelerated travel mode in case of stepping pedals forward; 
     FIG. 5 is a partially taken unfolded operational view for explaining forward accelerated travel mode in case of stepping pedals backward; 
     FIG. 6 is a perspective view showing the construction of principal parts of a traveling and accelerating system for bicycles according to the present invention, in which a conversion control part is set to a forward normal travel mode; 
     FIG. 7 is a perspective view showing the construction of principal parts of a traveling and accelerating system for bicycles according to the present invention, in which a conversion control part is set to a forward accelerated travel mode; and 
     FIG. 8 is a perspective view showing the construction of principal parts of a traveling and accelerating system for bicycles according to the present invention, in which a conversion control part is set to a backward accelerated travel mode. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 to FIG. 8 show a construction of a traveling and accelerating system for bicycles according to an embodiment of the present invention, in which clutch bearings are adapted as forward and backward latch means. 
     FIG. 1 is a disassembled perspective view showing the construction of principal parts of a traveling and accelerating system for bicycles according to the present invention, and FIG. 2 is a partially taken unfolded view showing the construction of the traveling and accelerating system for bicycles according to the present invention, which is in an assembled state. 
     FIG. 3 is a partially taken unfolded operational view for explaining forward normal travel mode according to a selection of a conversion control part  100 , FIG. 4 is a partially taken unfolded operational view for explaining accelerated travel mode by a selection of the conversion control part  100 , and FIG. 5 is a partially taken unfolded operational view for explaining forward accelerated travel mode in case of stepping pedals  20  backward by a selection of the conversion control part  100 . 
     FIG. 6 to FIG. 8 are perspective views respectively showing principal parts of the traveling and accelerating system for bicycles according to the present invention, in which it is apparent to understand the movement of moving plates for controlling clutches according to the selections of the conversion control part  100 . 
     The bicycle includes a frame  10  forming a frame body of the bicycle, front and rear wheels, which are not shown but provided rotatably to the frame  10 , and a boss  21  fixed to mount the pedals  20  under a center of the frame  10  to support rotation of the pedals  20 . 
     The pedals  20  are fixed inside the boss  21  and a shaft  22  is rotatably inserted through the inside of the boss  21  by means of bearings (unshown). Therefore, when a user steps the pedals  20  at both sides of the boss  21 , rotational power is transmitted to the shaft  22  so that the rotational power drives a driven sprocket (unshown) at the rear wheel via a chain  31  by means of the driving sprocket  30  which is axially mounted on the shaft  22 , thereby the bicycle traveling forward. 
     The driving sprocket  30  which is axially mounted on the shaft  22  is positioned in a housing  40  to transmit the rotational power via the chain  31 . 
     The housing  40  is fixed on the frame  10  at one side of the boss  21  and closed with a cap  41  at its opening, accommodating various accessories therein, so that external impurities may be prevented from being introduced therein and viscosity of oil which is necessary for operating the accessories may be protected. 
     The housing  40  accommodates the driving sprocket  30 , a pinion  50 , a first gear member  60 , and a second gear member  70  therein. That is, in the housing  40 , the pinion  50  is axially fixed on the shaft  22  at one side of the driving sprocket  30  to rotate together with the driving sprocket  30 . 
     A clutch  80  for preventing reverse-driving is fixedly interposed between the driving sprocket  30  and the pinion  50 , thereby rotating together with the driving sprocket  30  and the pinion  50 . 
     When the pedals  20  are rotated in the clockwise direction for forward traveling, the clutch  80  interposed between the driving sprocket  30  and the pinion  50  connect the driving sprocket  30  and the pinion  50  and rotate them with each other. When the pedals  20  are stepped backward, the second gear member  70  is released from the driving sprocket  30  by means of a below-mentioned bearing clutch. 
     The housing  40  accommodates the first gear member  60  formed with an inner gear part  62 . 
     The inner gears  62  of the first gear member  60  are engaged with planetary gears  74  of the second gear member  70 , and the planetary gears  74  are mounted by means of a pin  75  and rotatable with relation to the pin  75  in the housing  40 . 
     The sleek inner peripheral  62  of the first gear member  60  has a peripheral formed without teeth, so that a clutch bearing  91  is inserted on the inner peripheral, the clutching bearing  91  being provided with a plurality of balls  91   c  and springs  91   d  in a predetermined interval. 
     The second gear member  70  is also inserted with a clutch bearing  92  in the same manner as the first gear member  60 . 
     The clutch bearings  91  and  92  are respectively formed with a plurality of grooves  91   a  and  92   a  in a predetermined interval and have slanted surfaces  91   b  and  92   b  respectively, so that the balls  91   c  and  92   c  and the springs  91   d  and  92   d  are respectively fitted into the grooves  91   a  and  92   a.    
     Therefore, when rotation direction of the clutch bearings  91  and  92  is different from that of the first and second gear members  60  and  70 , that is, different from that of the slanted surfaces  91   b  and  92   b , the balls  91   c  and  92   c  slide along the slanted surfaces  91   b  and  92   b  into positions where a distance from the first and second gear members  60  and  70  to the slanted surfaces  91   b  and  92   b  becomes narrow. 
     Then, the balls  91   c  and  92   c  are closed in the narrow space between the clutch bearings  91  and  92  and the first and second gear members  60  and  70 , so that the clutch bearings  91 ,  92  and the first and second gear members  60  and  70  become coupled integrally, thereby being controlled to rotate respectively in one direction. Detailed description with regard to the operation of the clutch bearings  91  and  92  is omitted since it has already been widely known in the routine mechanical fields. 
     Since the slanted surface  91   b  of the clutch bearing  91  is formed in an opposite direction to the slanted surface  92   b  of the clutch bearing  92 , the first gear member  60  and the second gear member  70  are controlled to rotate in a different direction from each other. 
     As the pedals  20  are stepped, the first gear member  60  and the second gear member  70  are selectively driven. In this case, the planetary gears  74  control traveling speed of the bicycle, for example, in 1:1 Forward Traveling Mode, Accelerated Traveling Mode or Backward Traveling Mode. 
     A conversion control part  100  is mounted outside the housing  40  to selectively control the latch member  85  to function in the 1:1 Forward Traveling Mode, Accelerated Traveling Mode or Backward Traveling Mode. The conversion control part  100  controls the traveling by fixing any one or both of the first and second gear, members  60  and  70  not to rotate, or by making them rotate freely. 
     A lever  110  is positioned through outside and inside of the housing  40  and connected with the release cable  104  which is provided at a convenient position with the user, for example, a position around a handle of the bicycle, so that the user may change a position of the lever  110  by means of the release cable  104 , thereby controlling the rotation of the first gear member  60  and the second gear member  70  by means of a forward driving clutch bearing  130  and a backward driving clutch bearing  140 . 
     The forward driving clutch bearing  130  and the backward driving clutch bearing  140  are respectively positioned in the housing  40  and in the cap  41  to perform the 1:1 Forward Traveling Mode, Accelerated Traveling Mode or Backward Traveling Mode by fixing or releasing outer diameters of the first gear member  60  and the second gear member  70 . 
     The lever  110  is connected at its one end part to a conversion selection lever (unshown) and the release cable  104  which is positioned around the handle of the bicycle, so that rotation angle of the lever  110  is converted by a wire which is pulled in response to manipulation of the conversion selection lever. 
     In this case, the function of the forward driving clutch bearing  130  and the backward driving clutch bearing  140  correspond to that of the above clutch bearings  91  and  92 . 
     The first gear member  60  has the sleek inner peripheral  62  without teeth, so that the clutch bearing  130  is inserted in the inner peripheral  62 , the clutch bearing  130  being provided with a plurality of balls  131   c  and springs  131   d  in a predetermined interval. 
     The second gear member  70  is also inserted on its outer diameter with the clutch bearing  140  in the same manner as the first gear member  60 . 
     The clutch bearings  130  and  140  are respectively formed with a plurality of grooves  131   a  and  141   a  in a predetermined interval and have slanted surfaces  131   b  and  141   b  respectively, so that the balls  131   c  and  141   c  and the springs  131   d  and  141   d  are respectively fitted into the grooves  131   a  and  141   a.    
     Therefore, when rotation direction of the clutch bearings  130  and  140  is different from that of the first and second gear members  60  and  70 , that is, different from that of the slanted surfaces  131   b  and  141   b , the balls  131   c  and  141   c  slide along the slanted surfaces  131   b  and  141   b  into positions where a distance from the first and second gear members  60  and  70  to the slanted surfaces  131   b  and  141   b  becomes narrow. 
     Then, the balls  131   c  and  141   c  are closed in the narrow space between the clutch bearings  130  and  140  and the firsthand second gear members  60  and  70 , so that the clutch bearings  130 ,  140  and the first and second gear members  60  and  70  become coupled integrally, thereby being controlled to rotate respectively in one direction. 
     The rotation of the first gear member  60  and the second gear member  70  is controlled by clutch pins  151 ,  161  of moving plates  150 ,  160  which move in response to position change of the lever  110  and control positions of the balls  131   c ,  141   c , thereby performing the Forward Traveling Mode, Accelerated Traveling Mode or Backward Traveling Mode. 
     The lever  110  is elastically mounted by a spring  111  and controlled its position according to manipulation of the user by means of the release cable  104 , thereby performing the Forward Traveling Mode, Accelerated Traveling Mode or Backward Traveling Mode. 
     The clutch pins  151 ,  161  of the moving plates  150 ,  160  are protruded toward the balls  131   c ,  141   c . The moving plates  150 ,  160  are elastically installed on a hook protrusion  163  to return to initial positions if external force of the spring  133  is not applied, and have protrusions  156 ,  166  to be inserted to grooves  112 ,  113  of the rotatably mounted lever  110 . 
     Therefore, as the protrusions  156 ,  166  moves by the lever  110 , the clutch pins  151 ,  161  controls the positions of the balls  131   c ,  141   c  and the coupling state of the clutch bearings  130 ,  140  and the first gear member  60  and the second gear member  70  to perform the travel modes. 
     The groove  112  of the grooves  112  and  113  of the lever  110  controls the protrusion  166  and is wide enough to allow the protrusion  166  to move therein. Accordingly, in case of normal accelerated forward traveling of two-stage dynamics to be described below, the protrusion  166  is released from the groove  112  of the lever  110 , and only in case of speed change of triple-stage dynamics for accelerated backward traveling, is controlled by the lever  110 . 
     In order to prevent possible damage caused by inside load of the housing  40 , a bracket  140  is provided and a thrust bearing  171  is preferably provided in the contact portions with the housing  40  and the cap  41 . 
     Now, operation by steps will be described in more detail. 
     (Forward Normal Travel) 
     Referring to FIG. 3 to FIG. 6, since the lever  110  connected to the release cable  104  is not pulled yet by the manipulation of the user, the lever  110  is in a most slanted position (see FIG. 3) so that the protrusions  156 ,  166  are separated to both end parts. Therefore, the clutch pins  151 ,  161  push the balls  131   c ,  141   c  into the deepest position of the slanted surfaces  131   b ,  141   b . 
     When the user steps the pedals  20  in the clockwise direction as shown by an arrow in FIG. 3, the clutch bearings  91  and  92  put on a square end portion of the shaft  22  rotate in a same direction, since the clutch bearings  130  and  140  are not engaged with the first and second gear members  60  and  70  by the balls  131   c ,  141   c.    
     Since the balls  92   c  are closed between the slanted surfaces  92   b  of the clutch bearing  92  and the second gear member  70  and the balls  91   c  are closed between the opposite slanted surfaces  91   b  of the clutch bearing  91  and the first gear member  60 , the clutch bearings  91  and  92  become coupled with the first and the second gear members  60  and  70  integrally, preventing backward rotation of the first gear member  60 . 
     The planetary gears  74  movably mounted to the second gear member  70  are engaged with the inner gear  62  of the first gear member  60 , so that it becomes impossible for the planetary gears  74  to rotate. 
     Therefore, when the pedals  20  are stepped by the user for forward traveling, the latch member  85  which is coupled with the first gear member  60  and the second gear member  70  rotates, so that the planetary gears  74  supported by the pins  75  race and the pinion  50  which is fixed by the driving sprocket  30  rotates in the clockwise direction, being engaged among the planetary gears  74 , thereby the driving power being transmitted to the rear wheels via the chain  31 . 
     In this case, the clutch  80  which is rotatably interposed between the driving sprocket  30  and the pinion  50  also rotates in the same direction when the pedals  20  are stepped by the user for forward traveling with the driving sprocket  30  and the second gear member  70  coupled. However, when the user steps the pedals  20  in the opposite direction, the second gear member  70  is released from the driving sprocket  30  by functions of the clutch bearings as described below. 
     Therefore, if the user stops stepping the pedals  20  or steps the pedals  20  backward, the latch  82  of the latch member  85  rotates in a direction to be released from the latch gear  73  of the second gear member  70 , so that the stopping of the rotation of the pedals  20  while traveling the bicycle or backward stepping of the pedals  20  become possible without transmitting the power. 
     (Accelerated Forward Traveling) 
     As shown in FIG.  4  and FIG. 7, according to manipulation of the lever positioned around the handle, the lever  110  connected to the release cable  104  becomes positioned in the center of its range of operation. 
     In this time, if the protrusion  156  of the moving plate  150  which is located toward the clutch bearing  130  is moved by the manipulation of the lever, the clutch pin  151  of the moving plate  150  makes the ball  131   c  retreat into the deepest position of the slanted surface  131   b  by elasticity of the spring  131   d.    
     Therefore, the first gear member  60  is fixed by the ball  131   c  which is forced to be pressed and only the second gear member  70  is rotatable. If the pedals  20  are stepped in the clockwise direction of an arrow of FIG. 5 for forward travel, the clutch bearings  91  and  92  rotate in the same direction. 
     Since the slanted surface  91   b  of the clutch bearing  91  is formed in an opposite direction to the slanted surface  92   b  of the clutch bearing  92 , the first gear member  60  is fixed by the forcibly pressed ball  131   c , while the second gear member  70  can be freely rotated. 
     The planetary gears  74  rotatably mounted on pins  75  of the second gear member  70  are engaged with the inner gear  62  of the first gear member  60 . When the second gear member  70  rotates, the planetary gears  74  race in response to the rotation of the second gear member  70  since a common center of the planetary gears  74  rotates in the sane direction with the second gear member  70 . 
     Simultaneously, the planetary gears  74  rotate by the inner gear  62  of the first gear member  60 , so that the pinion  50  being engaged among the planetary gears  74  obtains a rotation number which is increased by both racing and the rotation of the planetary gears  74 . 
     Therefore, when the pedals  20  are stepped by the user for forward traveling, the clutch  80  interposed between the driving sprocket  30  and the pinion  50  and the clutch bearing  92  which are coupled with the second gear member  70  rotate in the same direction with the second gear member  70 , so that the pinion  50  which is coupled with the driving sprocket  30  is accelerated in its rotation by a speed ratio of the planetary gears  74  positioned between the inner gear  62  of the stopped first gear member  60  and the pinion  50 , thereby the driving power being transmitted to the rear wheels via the chain  31 . 
     (Accelerated Forward Traveling by Backward Rotation of the Pedals) 
     As shown in FIG.  5  and FIG. 8, if the lever  110  connected to the release cable  104  is moved to be in most perpendicular position, the protrusion  166  of the moving plate  160  which is controlled by the groove  112  of the lever  110  moves in the opposite direction of the lever  110  and the protrusion  156  of the moving plate  150  moves in the opposite direction of the protrusion  166 , such that the protrusions  156  and  166  are arranged perpendicularly. Therefore, the clutch pins  151 ,  161  of the moving plates  150 ,  160  move the balls  131   c ,  141   c  to the lowest position of the slanted surfaces  131   b ,  141   b  by the elastic force of the springs  131   d ,  141   d.    
     Therefore, the first gear member  60  can be rotated, but the second gear member  70  becomes coupled with the clutch bearing  140 . The clutch bearing  92  can be rotated with the second gear member  70 . 
     If the user manipulates the pedals  20  in the counterclockwise direction as shown by an arrow of FIG. 5, the clutch bearings  91 ,  92  which are connected to the pedals  20  via the shaft  22  also rotate backward. 
     The balls  91   c  of the clutch bearing  91  are moved along the slanted surfaces  91   b  and closed to the first gear member  60 , such that the first gear member  60  is controlled in its rotation by the clutch bearing  91 . Accordingly, when the pedals  20  are rotated in the counterclockwise direction, only the planetary gears  74  can be rotated on the pins  75  in forward direction so as to transfer the power to the pinion  50 . 
     The driving sprocket  30  geared to the pinion  50  is rotated so as to transfer the rotary power to the rear wheel. 
     In this case, the balls  92   c  of the clutch bearing  92  are also moved along the slanted surfaces  92   b  and closed to the second gear member  70 . Therefore, the balls  91   c  may move toward the deepest position of the slanted surface  91   b , and the first gear member  60  is fixed forward and rotatable backward. 
     On the other hand, the second gear member  70  is fixed backward and rotatable forward by the clutch bearing  92 . 
     In the meantime, the planetary gears  74  movably mounted to the second gear member  70  are engaged with the inner gear  62  of the first gear member  60 , so that the planetary gears  74  rotate but not race. 
     Therefore, when the pedals  20  are stepped by the user for backward traveling, the latch member  85  and the clutch bearing  91  rotate backward being coupled with the first gear member  60 , so that the planetary gears  74  supported by the pins  75  rotates and the pinion  50  which is engaged among the planetary gears  74  rotate normally in the forward direction, thereby transmitting the driving power to the rear wheels via the chain  31  in the opposite direction to the rotation of the pedals  20 . At this time, the rotation ratio is accelerated. 
     In the meantime, if the pedals  20  are rotated in the forward normal direction, contrary to the above, by the functions of the clutch bearings  91 ,  92 ,  130 , and  140 , the clutch bearing  140 , the second gear member  70 , and the clutch bearing  92  can slide with each other, and the first gear member  60  is controlled in its rotation by the clutch bearing  130 . 
     Accordingly, the planetary gears  74  are rotated backward with the inner gear  62  of the first gear member  60  and transfer the accelerated driving power to the pinion  50 , thereby the driving sprocket  30  has the accelerated forward normal traveling. In this condition, the bicycle according to the present invention can perform uniformly accelerated forward traveling regardless of direction of the rotation of the pedals  20 . 
     EFFECT OF THE INVENTION 
     According to the present invention as described hereinabove, if the user simply manipulates the operation lever, the bicycle may run forward regardless of the forward rotation and the backward rotation of the pedals, so that the user may develop their leg-muscles in balance without feeling as bored and tired as riding the prior art bicycle, as well as accelerate the running speed selectively. additional change gear is not necessary any more and the users may obtain a bicycle at a relatively low cost 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as described in the accompanying claims.