Abstract:
A retrofit for a thumb-lever throttle vehicle includes a rotatable handgrip which can be sleeved over a handlebar of a vehicle and a lever shoe which engages a thumb-lever throttle. Also included is an elongated coupler which couples between said handgrip and said lever shoe, such that said handgrip manipulates the thumb-lever throttle to control a fuel supply to an engine of the vehicle.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a hand-controlled throttle of a vehicle.  
         BACKGROUND OF THE INVENTION  
         [0002]    Motorcycles and other lightweight vehicles are generally controlled by a hand throttle, which moderates the engine speed of the vehicle. The throttle is generally mounted on the handlebar of the vehicle and connected by means of a cable or cables enclosed in conduits to the vehicle&#39;s engine.  
           [0003]    On motorcycles it is very common for the throttle to be controlled by a rotatable handgrip comprised of an elongated tubular handgrip commonly called a twist throttle. The handgrip is mounted on the end of the motorcycle&#39;s handlebar and held in place by means of a collar clamp assembly, which gives the handgrip the freedom to rotate. The collar clamp assembly further encloses a cable spool guide fastened to the end of the handgrip for winding and unwinding a control cable as the handgrip is rotated. Rotation of the handgrip controls the supply of fuel to the engine thus increasing or decreasing the speed of the vehicle.  
           [0004]    In some vehicles such as all terrain vehicles (ATV), sea scooters and snowmobiles there is commonly used a handlebar-mounted throttle with a thumb-controlled lever, which moderates the speed of the vehicles.  
           [0005]    Some users find the standard thumb controlled lever uncomfortable or inhibiting and manufacturers offer lever lengthening devices called thumb savers, which allow using the palm base to control the lever instead of the thumb.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention aims to provide a retrofit rotatable throttle control, which replaces a thumb-lever throttle used on various vehicles, such that the user is able to control the vehicle more easily with a rotatable hand grip device. This eliminates the fatigue that is often common to the continuous use of a thumb-lever throttle over lengthy periods of time and over long distances.  
           [0007]    According to a preferred embodiment of the present invention, there is provided a retrofit for thumb-lever throttle vehicles including a rotatable handgrip which can be sleeved over a handlebar of a vehicle, lever shoe which engages a thumb-lever of a thumb-lever throttle, and an elongated coupler which couples between the handgrip and the lever shoe, such that the handgrip manipulates the thumb-lever throttle to control a fuel supply to an engine of the vehicle.  
           [0008]    In accordance with some embodiments of the present invention, the handgrip is connected to a thumb-controlled lever using an enveloped and guided cable.  
           [0009]    Alternatively, the handgrip is connected to the thumb-controlled lever using an external flexible strap.  
           [0010]    Further alternatively, the handgrip is connected to the thumb-controlled lever using an external resilient strap.  
           [0011]    In accordance with some embodiments of the present invention, the handgrip includes a return spring, which returns the thumb-controlled lever to a set position, when the handgrip is released.  
           [0012]    In accordance with some embodiments of the present invention, a user can select between different response modes of the handgrip, in which, turning the handgrip by a set angle, moves the thumb controlled lever a smaller or larger distance.  
           [0013]    According to another preferred embodiment of the present invention, there is provided a direct-acting retrofit for a thumb-lever throttle vehicle including a rotatable handgrip adapted for rotatably sleeving over a handlebar of a vehicle. There is also included a retrofit thumb-lever member, having a thumb-lever, an axial operating shaft and a coaxial spool guide, arranged for operating a thumb-lever throttle, and an elongated coupler arranged for operatively coupling the handgrip to one or other of the thumb-lever and the coaxial spool guide, thereby to operate the thumb-lever throttle.  
           [0014]    According to an added embodiment of the present invention, the direct acting retrofit in which the retrofit thumb-lever member includes attachment means for fixably coupling the elongated coupler to the thumb-lever and for fixably coupling the elongated coupler to the coaxial spool guide.  
           [0015]    According to one other embodiment of the present invention, the direct acting retrofit, in which there is an elongated coupler, includes an enveloped and guided cable.  
           [0016]    According to another embodiment of the present invention, the direct acting retrofit includes the spool guide attachment means, which is radially adjustable so as to provide a variable operative association between the rotatable handgrip and the retrofit thumb-lever member.  
           [0017]    According to an additional embodiment of the present invention, a preselected angle of rotation of the handgrip moves the thumb-lever from a minimum position to a maximum position.  
           [0018]    According a further embodiment of the present invention, the rotatable handgrip of the direct acting retrofit includes a returning spring for returning the thumb-lever throttle to a preselected position.  
           [0019]    According to one other embodiment of the present invention, in the elongated coupler of the direct acting retrofit is formed from a substance including: steel, non-ferrous metal and plastic.  
           [0020]    According to another embodiment of the present invention, the thumb-lever throttle is operable using the thumb-lever.  
           [0021]    According to one added embodiment of the present invention, the rotatable handgrip includes a locking element for retaining the rotatable handgrip in a preselected operative position.  
           [0022]    According to an additional embodiment of the present invention, the thumb-lever member includes an operatively attachable coaxial spool guide and the coaxial spool guide is operatively attachable to said axial operating shaft of said thumb-lever member.  
           [0023]    According to one further embodiment of the present invention, the coaxial spool guide is operatively attachable to an axial operating shaft of the thumb-lever throttle. 
       
    
    
     BRIEF DESCRIPTION OF FIGURES  
       [0024]    Particular exemplary embodiments of the present invention will be described with reference to the following figures, wherein identical structures, elements or parts, appearing in more than one figure are preferably labeled with the same or similar reference numbers in all the figures in which they appear, in which:  
         [0025]    [0025]FIG. 1 is an illustration of a prior art thumb throttle mounted on a vehicle&#39;s handlebar, useful in explaining an exemplary embodiment of the present invention;  
         [0026]    [0026]FIG. 2 is an illustration of a handgrip connected to a thumb throttle, in accordance with an exemplary embodiment of the present invention;  
         [0027]    [0027]FIG. 3 is an illustration of a handgrip, in accordance with an exemplary embodiment of the present invention;  
         [0028]    [0028]FIG. 4 is an illustration of an exploded view of a handgrip, in accordance with an exemplary embodiment of the present invention;  
         [0029]    FIGS.  5 A- 5 E are illustrations of optional variations of a handgrip, in accordance with some exemplary embodiments of the present invention;  
         [0030]    FIGS.  6 A- 6 B are illustrations of a variation of a handgrip connected to a thumb throttle, in accordance with an exemplary embodiment of the present invention;  
         [0031]    FIGS.  7 A- 7 B are illustrations of a variation of a handgrip connected to a thumb throttle, in accordance with an exemplary embodiment of the present invention;  
         [0032]    FIGS.  8 A- 8 E are illustrations of a variation of a handgrip connected to a thumb throttle, in accordance with an exemplary embodiment of the present invention;  
         [0033]    [0033]FIG. 9 is a perspective view illustration of a retrofit thumb-lever member in operative association with the rotatable handgrip;  
         [0034]    [0034]FIG. 10 is a plan view illustration of the retrofit thumb-lever member in operative association with the rotatable handgrip shown in FIG. 9;  
         [0035]    [0035]FIG. 11 is a perspective view illustration of the retrofit thumb-lever member in operative association with the rotatable handgrip assembled on a handlebar;  
         [0036]    [0036]FIG. 12 is a perspective view illustration of the retrofit thumb-lever member;  
         [0037]    [0037]FIG. 13 is a perspective view illustration of a retrofit thumb-lever member having a radially adjustable spool guide connector;  
         [0038]    [0038]FIG. 14 is a plan view illustration of the retrofit thumb-lever member shown in FIG. 13;  
         [0039]    [0039]FIG. 15 is a perspective view illustration of a thumb-lever of retrofit thumb-lever member in operative association with the rotatable handgrip;  
         [0040]    [0040]FIG. 16 is a perspective view of an attachable spool guide connector and a thumb-lever member;  
         [0041]    [0041]FIG. 17 is a perspective view of an attachable spool guide connector operatively attached to a thumb-lever member; and  
         [0042]    [0042]FIG. 18 is a perspective view of the retrofit thumb-lever member with the attached spool guide connector in operative association with the rotatable handgrip.  
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0043]    [0043]FIG. 1 is an illustration of a prior art thumb throttle referenced  10  mounted on a vehicle&#39;s handlebar referenced  35 . This illustration is useful in explaining an exemplary embodiment of the present invention. A user typically grasps a handlebar end referenced  37  of handlebar  35  and uses his thumb to move a lever referenced  20  of thumb throttle  10 , which regulates the fuel flow to the engine. Thumb throttle  10  is connected to the vehicle&#39;s engine by a cable referenced  30  typically made of a strong and flexible material. Examples of cable  30  include a twine made from steel or other metal or a flexible rod made from plastics or other substances. Cable  30  is typically protected in a reinforced plastic or rubber conduit referenced  25 .  
         [0044]    Some users of vehicles with handlebar steering prefer regulating the fuel flow to the engine with a handgrip such as implemented in motorcycles and some users prefer a thumb throttle  10  such as in vehicles mentioned in the background of this application.  
         [0045]    In an exemplary embodiment of the present invention, a cam device referenced generally  100 , illustrated in FIG. 3, is retrofitted over thumb throttle lever  20  and handlebar end  37  to allow control of lever  20  using a handgrip  15 . Cam device  100  converts the rotational motion of handgrip  15  to a linear motion of lever  20 .  
         [0046]    Although cam device  100  is illustrated and described as a retrofit over thumb-lever throttle  20  of a vehicle, it should be noted that it can be adapted to retrofit over other user controls of a vehicle, for example over a control for changing gears.  
         [0047]    [0047]FIG. 2 and FIG. 4 will be used in conjunction with FIG. 3 to explain the implementation and function of cam device  100 . FIG. 3 illustrates cam device  100 . FIG. 2 illustrates cam device  100  fully deployed on a handlebar  35  of a vehicle. FIG. 4 illustrates an exploded view of cam device  100 .  
         [0048]    In an exemplary embodiment of the present invention, handgrip  15  is inserted like a sleeve over handlebar end  37 . In accordance with some embodiments of the present invention, handgrip  15  is held in place with the freedom to rotate by the parts listed infra. One end of handgrip  15  comprises a spool guide referenced  85 , mounted transversely on handgrip  15  (illustrated in FIG. 4). Optionally spool guide  85  is shaped primarily as a circle. Alternatively spool guide  85  is elliptical or any other shape, providing a varying response to the rotation of handgrip  15  at different angles of rotation.  
         [0049]    In accordance with some embodiments of the present invention, an upper collar clamp referenced  40  and a lower collar clamp referenced  45 , fit over cable spool guide  85  at the end of handgrip  15 . Upper collar clamp  40  and lower collar clamp  45  are locked together with fastener pins referenced  70 . Alternatively other methods are implemented to hold handgrip  15  in place over handle bar end  37  which serves as an inner bearing and allows rotational freedom. For example by using a cap referenced  5  as will be described infra.  
         [0050]    In accordance with some embodiments of the present invention, handgrip  15  and lever shoe  60  are coupled by a cable  55  that converts the rotational motion of handgrip  15  to linear motion to move lever shoe  60 , which is fixably attached to lever  20 . Cable  55  is fastened to cable spool guide  85  at one end and to lever shoe  60  at the other end. Cable  55  is optionally formed from any flexible material such as plastic or metal twine.  
         [0051]    In accordance with some embodiments of the present invention, lever shoe  60  is optionally formed from an elastic material such as rubber in order to allow some freedom in fitting it over lever  20 . Alternatively lever shoe  60  is formed from a rigid material such as metal and attached to lever  20  for example with a screw (not shown). Alternatively, lever shoe  60  is configured as a slip-on case, for example, made from a fabric or cord and optionally fastened over lever  20  with a knot.  
         [0052]    In accordance with some embodiments of the present invention, cable  55  has a cable terminator referenced  75 , which latches into a cable terminator notch referenced  80  on cable spool guide  85 , and maintains cable  55  connected to cable spool guide  85 . Alternatively other methods are used to hold cable  55  to handgrip  15 , such as a fastener screw as suggested infra for the other end of cable  55 , terminating at lever shoe  60 .  
         [0053]    In accordance with some embodiments of the present invention, cable  55  is directed toward lever  20  by a cable guide referenced  50  in order to arrange for cable  55  to pull lever shoe  60  parallel to the direction of motion. Optionally, cable  55  wraps around cable spool guide  85 , passing through cable guide  50  and emerging in the direction of lever  20 . Optionally, cable guide  50  is free to rotate relative to lower collar clamp  45  in order to direct cable  55  toward lever  20 .  
         [0054]    In accordance with some embodiments of the present invention, cable  55  is fixably connected onto lever shoe  60 , with a cable fastener screw referenced  65 . Alternatively, other methods known in the art are used depending on the construct of lever shoe  60  as mentioned supra.  
         [0055]    In an exemplary embodiment of the present invention, as illustrated in FIG. 4, cable spool guide  85  is formed having a narrow recess around its circumference to keep cable  55  in place as it wraps around cable spool guide  85 .  
         [0056]    In accordance with some embodiments of the present invention, cam device  100  does not inhibit the use of thumb throttle lever  20 , for example, due to the flexibility of its components. Thus, a user can control the vehicle as preferred, using thumb throttle lever  20  or handgrip  15 , or alternate between the two.  
         [0057]    In accordance with some embodiments of the present invention, cam device  100  includes a switch (not shown) that is adapted to prevent handgrip  15  from rotating. For example, the switch may be placed on upper collar clamp  40  and when pushed into upper collar clamp  40 , prevents movement of cable spool guide  85  handgrip  15  also cannot rotate. Optionally, a switch is used to select operation of the vehicle with thumb-lever  20 .  
         [0058]    FIGS.  5 A- 5 E are illustrations of optional variations of a handgrip  15 , in accordance with some exemplary embodiments of the present invention.  
         [0059]    In an exemplary embodiment of the present invention as illustrated in FIG. 5D and FIG. 5E, cable spool guide  85  has an inner radius referenced  81 , which is approximately equal to the radius of handgrip  15 , and an outer radius referenced  82 . Radius  82  has a proportionate circumference about which cable  55  is wrapped. Circumference relative to radius  82 , as shown in FIG. 5D, is proportionately larger than that shown in FIG. 5E and more of cable  55  is pulled onto cable guide  85  for the same angle of rotation of handgrip  15 .  
         [0060]    In FIG. 5A, spool guide  85  has a radius  82 , which is much larger, relative to inner radius  81 , than spool guide  85  shown in FIG. 5B. Therefore, a small rotation of handgrip  15  shown in FIG. 5A will pull lever  20  (FIG. 2), a greater distance than an equally small rotation of handgrip  15  as shown in FIG. 5B, so as to cause a larger change to the rate of fuel supply to the engine.  
         [0061]    In accordance with some embodiments of the present invention, radius  82  is selected such that three quarters of a full rotation (270°) of handgrip  15 , causes thumb-lever  20  to move from its minimum position to its maximum position. In accordance with some embodiments of the present invention, half a rotation (180°) of handgrip  15 , is sufficient to move thumb-lever  20  from its minimum to its maximum position. Alternatively, a fourth of a full rotation (90°) is sufficient to move thumb-lever  20  from its minimum to its maximum position. Further, alternative radii  82  may be selected to provide additional angles of rotation so as to cause thumb-lever  20  to move from its minimum position to its maximum position.  
         [0062]    In accordance with some embodiments of the present invention, as shown in FIG. 5D, the selected size of radius  82  is much larger than the size of radius  81  of handgrip  15  (e.g. twice the size). Alternatively as shown in FIG. 5E the selected size of radius  82  is only slightly larger than the size of radius  81  of handgrip  15  (e.g. 10% larger).  
         [0063]    In accordance with some embodiments of the present invention, for example, cable spool guide  85  may be shaped like an ellipse having varying radii  82  at different angles.  
         [0064]    In accordance with some embodiments of the present invention as illustrated in FIG. 5C, handgrip  15  comprises two cable spool guides  85  such as those seen in FIGS. 5A and 5B. When installing cam device  100 , a user selects attachment of cable  55  (FIG. 4) to either the larger cable spool guide  85  or to the smaller cable spool guides  85 . Alternatively or additionally, means such as a switch, as described infra, are supplied to select the larger or smaller cable spool guide  85 . Optionally more than one cable is connected between handgrip  15  and lever shoe  60 , cable spool guides  85  are not fastened to handgrip  15  but rather rotate freely about handgrip  15 . A user can lock a selected spool guide  85  to handgrip  15  during installation, for example, with a tightening screw referenced  88 , as illustrated in FIG. 4.  
         [0065]    FIGS.  8 A- 8 E illustrate an exemplary embodiment of the present invention, in which the user can choose between one or more modes of operation by selecting an active cable spool guide  85 . As illustrated in FIG. 8A a switch referenced  77  replaces cable end  75  in order to allow selection of an active cable spool guide  85 . Switch  77  and cable spool guides  85  are enclosed in a protective housing  47  (FIG. 8B), which keeps switch  77  in place. FIGS.  8 A- 8 E illustrate embodiments of the present invention with two cable spool guides  85 .  
         [0066]    Optionally more than two cable spool guides are employed to allow selection of multiple modes providing varying response rates to rotation of handgrip  15 .  
         [0067]    In an exemplary embodiment of the present invention, when handgrip  15  is in its rest (untorqued) position, a user can select a larger or a smaller cable spool guide  85 , as described supra, by moving switch  77  to the right or left side as illustrated in FIGS. 8C and 8D.  
         [0068]    In accordance with some embodiments of the present invention one or more springs referenced  110  and/or  115  are placed on either or both sides of housing  47  (as illustrated in FIG. 8E) on switch  77  in order to set a preferential position for switch  77 .  
         [0069]    In accordance with some embodiments of the present invention, a returning spring referenced  105  (FIG. 4) is connected for example between handgrip  15  or cable spool guide  85  and upper collar clamp  40  or lower collar clamp  45 . The returning spring assists in returning handgrip  15  to its rest (untorqued) position (i.e. optionally releasing lever  20 , when handgrip  15  is released). A stronger spring requires a user to exert more force in order to turn handgrip  15 , thus, in accordance with some embodiments of the present invention a user selects a spring according to the force desired to rotate handgrip  15 .  
         [0070]    In accordance with some embodiments of the present invention, spring  105  is formed from metal or any other known elastic material. Alternatively spring  105  comprises an elastic material in the form of a flat elastic band.  
         [0071]    In accordance with some embodiments of the present invention, cable  55  comprises a spring or spring like material and acts as a returning spring. Alternatively or additionally, cable  55  is sheathed by a spring.  
         [0072]    FIGS.  6 A- 6 B are illustrations of an exemplary implementation of a variation of cam device  100  deployed on a vehicles handlebar  35  according to an exemplary embodiment of the present invention. In FIGS.  6 A- 6 B the connection between handgrip  15  and lever shoe  60  is achieved using an external flexible strap referenced  90  made, for example, from plastic or metal or any other suitable material. Flexible strap  90  wraps externally around a strap guide referenced  95  and differs from cable  55  by being generally more rigid. Thus, it is not installed internal to an enveloping guide  50  and encasement (upper clamp  40  and lower clamp  45 ) like cable  55  but rather is fastened at the ends and guided by strap guide referenced  95 . In accordance with some embodiments of the present invention, an external flexible strap allows a user to visually assure the functionality of the connection, whereas an internal cable may snap without warning.  
         [0073]    In an exemplary embodiment of the present invention, strap guide  95 , configured as a solid circular circumference (as shown in FIGS.  6 A- 6 B) is fitted onto handgrip  15 . Flexible strap  90  is fixed to strap guide  95  and connected to lever shoe  60 . By turning handgrip  15  lever  20  is pulled toward handgrip  15  or released, thus handgrip  15  moderates the fuel flow to the engine.  
         [0074]    In accordance with some embodiments of the present invention, strap guide  95  is configured as only parts of a solid circle, for example, an inner circumference, an outer circumference and two radial flaps, as shown by the dotted lines in FIG. 6A.  
         [0075]    FIGS.  7 A- 7 B illustrate an exemplary implementation of cam device  100  according to an exemplary embodiment of the present invention. In FIGS.  7 A- 7 B the connection between handgrip  15  and lever shoe  60  is achieved using an external resilient strap  90  made for example from plastic or metal or any other suitable material. Resilient strap  90  is able to push and pull lever shoe  60  and is guided by a strap guide  95  comprising only a small arc for example a fourth of a complete circle (as illustrated in FIGS.  7 A- 7 B). Optionally, strap guide  95  is non circular, for example an elliptic arc thus causing a varying response to turning handgrip  15 .  
         [0076]    In accordance with some embodiments of the present invention, lever shoe  60  is configured as one piece with resilient strap  90 , for example, a one-piece plastic molding.  
         [0077]    In accordance with some embodiments of the present invention strap guide  95  and lever shoe  60  are coupled using a rigid bar with a hinge on both ends (not shown), connected at one end to a strap guide  95  (such as shown in FIG. 6A) and at the other end to lever shoe  60 . This coupling effectively causes strap guide  95  to directly operate shoe  60 . The hinges allow a minimal degree of freedom so that the connection will not break as handgrip  15  is rotated.  
         [0078]    In accordance with some embodiments of the present invention, a cap  5  is inserted into the end of handlebar  35 . Cap  5  prevents dust and moisture from entering handlebar  35 , allows attaching streamers and/or helps to prevent handgrip  15  from sliding off handlebar end  37 . Alternatively, cap  5  is inserted into handgrip  15  or handgrip  15  is sealed on the end.  
         [0079]    In accordance with some embodiments of the present invention, the end of handgrip  15  as illustrated in FIG. 6A and FIG. 7A includes a circular ring similar to cable spool guide  85  as shown in FIG. 5B. Notch  80  is not needed in order to keep handgrip  15  in place on handlebar  35  under upper clamp  40  and lower clamp  45  and to allow rotational motion.  
         [0080]    Optionally, handlebar end  37  is covered with a protective cover for example a fixed handgrip made of rubber or plastic, over which handgrip  15  is fitted and able to rotate smoothly. Alternatively, the protective cover is removed in order to install handgrip  15 . In addition, handgrip  15  is manufactured having different diameters in order to fit different types and models of vehicles. Furthermore, cam device  100  may be fitted to a handle bar in accordance with a variety of configurations. For example, one exemplary configuration is a handgrip  15 , comprising an upper and lower portions, which are assembled over handlebar end  37 . Thus handgrip  15  may be assembled directly over handlebar end  37  instead of being slipped on.  
         [0081]    Additionally, one or more slip rings of suitable sizes are inserted over handlebar end  37  to support handgrip  15 , thus preventing handgrip  15  from wobbling and allowing smooth rotation. Optionally, the slip rings include ball bearings to further reduce friction. Alternatively, cam device kit  100  is provided with one or more slip rings of various sizes, in order to match various sized handlebar ends  37  and handgrip  15 . Further, a cylindrical shaped support, for example, formed from plastic or other suitable material, is slid onto handlebar end  37  in order to support handgrip  15 . Optionally, the cylindrical shaped support is configured having grooves or protrusions about its circumference, which match respective grooves or protrusions within handgrip  15  in order to achieve smooth rotation of handgrip  15 .  
         [0082]    Handgrip  15  is generally more comfortable to use than thumb throttle lever  20  since it is controlled by a users hand, which is generally already gripping handle bar end  37  to steer the vehicle. Muscles are not subject to fatigue or trauma as is the case when controlling a thumb throttle lever  20  continuously with the thumb. Handgrip  15  also offers less distraction for a user than a thumb throttle lever  20 , since a users hands are generally on handle bar ends  37 . A user need not divert his line of sight in order to place his thumb over thumb throttle lever  20 .  
         [0083]    Also, handgrip  15  overcomes user handicap limitations, for example, of users with problems using their thumbs. Optionally, in order to enhance a user&#39;s grip or enhance a user&#39;s comfort, handgrip  15 , is covered or coated with an optional substance such as rubber or sponge.  
         [0084]    Reference is now made to FIGS.  9 - 12 , in which are illustrated an alternative provision to operate the thumb-lever throttle  10 , in accordance with a further embodiment of the present invention. The original thumb-lever  20  is replaced with an alternative thumb-lever member generally referenced  110 . Thumb-lever member  110  is formed having a thumb-lever referenced  115 , an axial operating shaft referenced  120  and coaxial spool guides referenced  125 . Thumb-lever  115  has an attachment aperture referenced  130  and fastening screw referenced  135 , disposed at the extremity of lever  115 . Spool guides  125  have a cable terminator fastener referenced  140  so as to retain a cable terminator referenced  142  and operating cable referenced  55  between guides  125 .  
         [0085]    One end of operating cable  55  is connected to cable terminator notch  80  of spool guide  85  (as disclosed hereinabove in relation to FIG. 4) of handgrip  15 . Cable  55  passes through cable guide  50  so as to attach cable terminator  142  to cable terminator fastener  140 . Rotating handgrip  15  in accordance with arrow  145 , thumb-lever member  110  is rotated in accordance with arrow  147 , thereby to operate thumb-lever throttle  10 .  
         [0086]    There is seen in FIG. 12, that provision is only made for a single point of attachment of cable  55  to spool guides  125 , so that the operational association between rotation of handgrip  15  and throttle  10  is fixed. Optionally, a variety of spool guides  125  having different shapes and sizes are formed separately from and attachable to operating shaft  120 .  
         [0087]    Referring now to FIGS.  13 - 14 , there is seen, in accordance with an alternative embodiment of the present invention, a thumb-lever member referenced  150  having extended spool guides referenced  152  and  153 . Guide  153  has disposed therein an adjusting slot referenced  160  and slidably attached thereto is a cable attachment block referenced  155  and attachment screw referenced  157  as well as a slot locking screw referenced  175 . Cable  55  is adjustably attached between spool guides  152  and  153  by cable attachment block  155  and screw  157 . The radial distance of the point of attachment is variable between the extremities of slot  160  as indicated by arrows  165  and  170  so as to provide varying throttle operation in accordance with the rotation of handgrip  15 .  
         [0088]    In accordance with an additional embodiment of the present invention, referring now to FIG. 15, cable  55  is attached to attachment aperture  130  using fastening screw  135  so as to provide direct operation of thumb-lever  115  by rotating handgrip  15 . Further, in regard to each of the embodiments recited hereinabove in relation to FIGS.  9 - 15 , the driver of the vehicle is able to operate thumb-lever member  110  by pressing lever  115  instead of by rotating handgrip  15 .  
         [0089]    In accordance with further embodiments of the present invention, referring now to FIGS.  16 - 18 , there is seen a separately formed spool guide generally referenced  200  (FIG. 16), which is operatively attachable to an axial operating shaft referenced  220  of a thumb-lever member referenced generally  210 . Spool guide  200  is formed having one or more cable terminator fasteners referenced  202  spaced at different radial distances from the axis of rotation of thumb-lever member  210  to so as to provide varying throttle operation in accordance with the rotation of handgrip  15 . Furthermore, in accordance with one attachment variation, spool guide  200  has a sleeve referenced  204  thereby to sleeve-fit spool guide  200  over axial operating shaft  220  as seen in FIG. 17. In order to sleeve-fit spool guide  200  to thumb-lever member  210 , thumb-lever member  210  is removed from thumb-lever throttle  10  (as disclosed hereinabove in relation to FIG. 11). Furthermore, there is seen in FIG. 18, thumb-lever member  210 , having spool guide  200  attached thereto, in operative engagement with handgrip  15  by means of cable  55 .  
         [0090]    It will be appreciated by persons skilled in the art that the example, of a sleeve-fit mechanism disclosed hereinabove in relation to FIGS.  16 - 18 , represents one of many alternative attachment means for attaching a spool guide to a thumb lever throttle.  
         [0091]    The present invention has been described using non-limiting detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the present invention. It should be understood that features and/or steps described with respect to one embodiment may be used with other embodiments and that not all embodiments of the present invention have all of the features and/or steps shown in a particular figure or described with respect to one of the embodiments. Variations of embodiments described will occur to persons of the art.  
         [0092]    It is noted that some of the above described embodiments may describe the best mode contemplated by the inventors and therefore may include structure, acts or details of structures and acts that may not be essential to the present invention and which are described as examples. Structure and acts described herein are replaceable by equivalents, which perform the same function, even if the structure or acts are different, as known in the art. Therefore, the scope of the present invention is limited only by the elements and limitations as recited in the claims. When used in the following claims, the terms “comprise”, “include”, “have” and their conjugates mean “including but not limited to”.