Abstract:
A pair of cams having helical ramps rotate on each other to produce an extension or retraction of the cams. A handle on one of the cams provides leverage for turning the cam to convert radial force to axial force. The cams can be used in conjunction with a shaft and ratchets to produce jacks. The cams can also be used to produce clamps such as for securing lids to containers. When a shaft is secured at one cam and connected to a trailer, truck or other vehicle bed, an object can be secured to the vehicle bed by the other cam engaging and placing a downward force on the object when in the extended position. When used as a clamp the cams can secured or release the object being held with a partial rotation of the cam. The cams are simple one piece devices having a bearing portion on one cam inserted into a bore on the other cam to provide concentric rotation of the cams. There are no moving parts to wear out or break. The cams and handle can be scaled up or down to any size needed.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to devices for translating a radial force into axial motion and/or force and more particularly to a helical ramp with a bearing and/or bearing surface in the center for transforming a radial force to axial movement. 
     II. Discussion of the Prior Art 
     Most latches, clamps and jacks have a lever with a linear motion moving in the same direction as the object to be moved. The leverage obtained depends on the lever length. These devices are frequently not easy to use because the lever moves toward the object leaving very little room to maneuver and frequency limiting the length of the lever. 
     Many latches, clamps and jacks have more than one moving part which increases the cost of making and assembling the device. These devices have several parts with pivot points with one part inserted into and pivoting thereon. These multiple parts are subject to wearing out and breaking. 
     A lever arm that moves radially and translates an object axially is preferred in some applications. By using ramps sliding on each other there are no moving parts to assemble and no assembled parts to break. 
     SUMMARY OF THE INVENTION 
     A pair of opposing helical ramps are used for translating an object axially when the ramps are rotated relative to each other. A handle on one ramp when moved radially turns the ramp such that it slides up or down on the opposing static ramp to translate an object axially. 
     Upper and lower cams both have at least one opposing ramp surface such that they slide on each other. No levers having pivot points and connections therefore are used. A bearing on one cam extends into a bore on the other cam so that the helical ramps move concentrically. 
     The ramps have walls which prevent the ramps from being radially translated past the ends of the ramps. The ramps also have three dimensional sine wave portions which nest with each other to limit rotation and provide a locking position which takes some force to overcome. 
     A locking pin can be inserted into a bore through both the upper and lower cams to ensure that the cams will not rotate relative to each other. A locking pin member having two arms can fit over the lever on the upper cam. The locking pin member may have apertures for inserting a safety pin ensuring the locking pin cannot be removed from the handle, or a lock can be used through the apertures on the arms of the locking pin member, for security, ensuring the locking pin can not be removed. 
     A shaft through the center of the upper and lower cams can be attached to an object temporarily by inserting one end into a coupler, or the shaft can be permanently attached to an object. The upper cam receives the shaft and, with a threaded shaft, the usable length of the shaft can be adjusted by treading a nut on the shaft. 
     In some embodiments a pair of ratchets on the shaft allows multiple turns of the handle to raise or lower an object. 
     One embodiment of the invention uses a bar through an aperture on the lower cam member. The lower cam member is thereby fixed in position such that it cannot rotate. The upper cam rotates by use of the handle. The bar is moved upward or downward when the handle is translated. One use is for securing a snowmobile to a trailer. The shaft is inserted into a coupler on the trailer, the bar is placed over the skis on the snowmobile. The adjustment nut is threaded onto the shaft that runs through the center of the lower and upper cam for a tight fit of the bar on the snowmobile skis when the handle is rotated to the locking position such that the cams apply an axial force on the bar extending over the snowmobile skis, securing the snowmobiles to the trailer they are being transported on. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to provide a means for quickly clamping one object to another. 
     It is an object of the invention to raise or lower objects. 
     It is an object of the invention to convert a radial force to an axial force. 
     It is an object of the invention to secure an object from moving. 
     It is an object of the invention to extend and retract a pair of cams by using helical ramps. 
     It is an object of the invention to secure a snowmobile on a trailer. 
     It is an object of the invention to provide a lockable clamp to secure objects. 
     It is an object of the invention to provide a stop for the cams to prevent rotation beyond a portion of a revolution either clockwise or counterclockwise. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of the upper cam member and lower cam member in the retracted state. 
     FIG. 2 is a side view of the upper cam member and lower cam member in the extended state. 
     FIG. 3 is a side view of the sine wave segment of the upper cam member and lower cam member at the peak of the cams extension. 
     FIG. 4 is a perspective view of the upper cam member. 
     FIG. 5 is a perspective view of the lower cam member. 
     FIG. 6 is a perspective view of the upper cam member and lower cam member in the extended state. 
     FIG. 7 is a perspective view of the upper cam member and lower cam member in the retracted state. 
     FIG. 8 is a perspective view of the handle. 
     FIG. 9 is a sectional perspective view of the upper and lower cam members in a jack embodiment with ratchets engaging the shaft and the cams extended. 
     FIG. 10 is a sectional perspective view of the upper and lower cam members in a jack embodiment with ratchets engaging the shaft and the cams retracted. 
     FIG. 11 is a sectional perspective view of the upper and lower cam members with the shaft about to engage a coupler on a trailer bed. 
     FIG. 12 is a view of the upper and lower cam members with the shaft engaging a coupler and a bar pressing a pair of snowmobile skis down on a trailer bed. 
     FIG. 13 a top perspective view of the upper and lower cam members in their extended state with the shaft engaging the coupler. 
     FIG. 14 is an exploded view of the upper and lower cams with a bar and coupler for attachment to a trailer. 
     FIG. 15 is a perspective view of the lock pin member. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the device and associated parts thereof. Said terminology will include the words above specifically mentioned, derivatives thereof and words of similar import. 
     FIG. 1 shows the rotatable ramp jack  150  in a retracted position where the upper cam  24  and the lower cam  22  are engaged along all adjacent surfaces and the distance between the top surface  60  of upper cam  24  and the bottom surface  90  of the lower cam  22  is at a minimum. With the lower cam  22  fixed in position the upper cam  24  may be rotated by a force applied to handle  26  leftwardly forcing ramp surface  80  on upper cam member  24  to slide along adjacent ramp surface  30  on lower cam member  22  until stopped from further rotation, with the cams in their extended position, by sine wave segments  120  and  140  nesting in each other and end walls  125  and  145  blocking further rotation as shown in FIG.  2 . 
     The nesting of sine wave segments  120  and  140  when the cams  24  and  22  are being forced together will usually be enough to prevent further rotation of the cams  24 ,  22  relative to each other. End walls  125  and  145  ensure that no further rotation of the cams  24 ,  22  are possible particularly if the load on the cams forcing them together is not strong. 
     A portion of the upper and lower cam members  24  and  22 , illustrating the sine wave segments  120  and  140 , are shown in FIG. 3 with upper and lower cam members the sine wave segments engaging at their peaks  124  and  142  respectively. Just prior to this point, as the upper cam member  24  moves leftwardly, the upward slope portion  85  of the sine wave segment  120  engaged the ramp surface  30  on lower cam member  22 . The maximum pressure between the upper and lower cam members  24  and  22  occurs at this position requiring the most force on handle  26 . Thereafter the upper and lower cam member&#39;s  24  and  22  sine wave segments  120 ,  140  nest as shown in FIG. 2, with peak  124  in trough  144  and peak  142  in trough  122 , relieving some of the force on the upper and lower cam members  24  and  22  providing an energy well which must be overcome to further rotate the upper and lower cam members  22  and  24  relative to each other. Therefore the cams  24 ,  22  tend to stay in the nested position, particularly if the force pressing the upper and lower cam members  24 ,  22  together is great. The distance between the top surface  60  of upper cam member  24  and the bottom surface  90  of the lower cam member  22  is at a near maximum when the cams  24  and  22  are nested. The difference in distance from the top surface  60  to the bottom surface  90  in the retracted and extended positions represents the extent of the useful pulling or pushing force that can be applied by the rotatable ramp jack  150  in one cycle of operation. 
     As is readily apparent to one skilled in the art the length of the ramp, the angle of incline of the ramps and length of the handle can all be varied to provide different mechanical advantages depending on the use of the device. 
     FIG. 4 shows a perspective view of the upper cam member  24 . The upper cam member  24  has a top surface  60  having three screw holes  62 , a lock pin bore  66  and a hexagonal raised portion  64 . 
     FIG. 8 shows a top perspective view of handle  26 . The handle  26  has a plate portion  75  having a hexagonal aperture  70 , screw holes  72  and lock pin hole  76 . 
     The hexagonal aperture  70  in handle  26  is placed over the hexagonal raised portion  64  of the upper cam member  24  ensuring that the screw holes  72  and lock pin hole  76  in handle  26  are aligned with the corresponding screw holes  62 , and lock pin hole  66  in upper cam member  24 . 
     The hexagonal raised portion  64  on upper cam member  24  can be used to turn the upper cam member  24  with a wrench, a socket wrench or with the handle  26 , with or without the handle  26  being secured by screws  57 . 
     The upper cam member  24  (see FIG. 1) has an edge  35  for engaging edge  36  on lower cam member  22 . When the two edges  35  and  36  meet further rotation of the upper and lower cam members  24 ,  22  is blocked and the cam members are in their retracted configuration. 
     In order to keep the ramp surfaces  80  and  30  on the upper and lower cam members  24  and  22  concentric as they rotate, the upper cam member  24  has a cylindrical bearing  100  (FIG. 4) extending downward to engage and rotate inside of a bore defined by wall  130  (FIG. 5) in lower cam member  22 . The beveled portion  102  of bearing  100  helps insert the upper cam member  24  into the lower cam member  22 . 
     Referring to FIGS. 1,  4  and  5 , the indented portion  41  on the upper cam member  24  receives the ridge  51  on the lower cam member  22  when the upper and lower cam members  24 ,  22  are in their retracked position. 
     Alignment ribs  160  and  162  are aligned when the upper and lower cam members  24 ,  22  are in their retracted position (see FIG.  7 ). In the embodiment with only one locking pin bore  67  in the lower cam member  22  it is important to align the alignment ribs  160  and  162  such that the lock pin  55  extends through lock pin bores  66 ,  67  to the ensure the that the upper and lower cam members  24 ,  22  are locked in position. An alternative design could include three bores  66  and  67  rotated 120° from the center of cams  24  and  12 , to eliminate the use of the alignment ribs  160  and  162 . 
     FIG. 14 shows a perspective view of the locking pin member  155  having two arms  156 ,  157  for extending over opposing sides of handle  26 . Apertures  171 ,  172 ,  173 ,  174  in the arms can receive a lock or safety pin  180  to ensure the locking pin member  155  can not be removed from handle  26 . 
     There are many uses for the rotatable ramp jack  150 . Whenever an object needs to be moved or one object needs to be secured to another the rotatable ramp jack  150  may be employed. 
     In one embodiment as shown in FIG. 9 ratchet  181  in the upper cam member  24  and ratchet  180  in bar  18  can be set to lift or lower shaft  40  as the upper cam  24  is turned by handle  26 . In the embodiment shown the lower cam member  22  engages bar  18  having a bore  38  such that shaft  40  having hook  185  can be attached to and raise or lower an object. As can be easily understood the rotatable ramp jack  150  can also have the shaft  40  extending upwardly to push on an object such as for lifting a car when used as a car jack. 
     In a second embodiment as shown in FIG. 11 pin  42  extends though the shaft  40  for engaging a coupler  46  attached to the trailer bed  14 . The coupler  46  has curved arms  196 ,  197  designed to easily engage the pin  42  in shaft  40  when the shaft is placed between the arms  196 ,  197  and pulled upward. The upper cam member  24  has a counter bore  50  extending part way through the upper cam member  24 . A bore  48  extends downwardly from the counter bore  50  such that a threaded shaft  40  can be inserted into the bore  48  and a nut  54  screwed onto the shaft  40  will hold the shaft  40  to the upper cam member  24  preventing downward movement of the shaft  40 . The shaft  40  can be adjusted upwardly or downwardly on the upper cam member  24  by turning the nut  54  on shaft  40 . Since the nut  54  is recessed into the counter bore it will be relatively tamper proof and secure since no tool can easily access the nut  54  to remove it or loosen it. The shaft  40  can be extended upwardly and the nut  54  attached and then the shaft  40  with the nut thereon lowered into the upper core member  24 . If the nut  54  and the counter bore  50  are about the same size and the nut  54  is recessed into the counter bore  50  then it will be difficult to remove or loosen the nut  54 . 
     As shown in FIGS. 12 and 13, when the shaft  40  engages coupler  46  and bar aperture  118  on lower cam member  22  engages bar  18 , the lower cam member  22  will be prevented from rotating and secure the bar  18  with downward force to engage snowmobile skis  10 ,  12  securing the snowmobile to the trailer  14 . In this manner the snowmobile is prevented from moving around in the trailer during transport and is secured from theft when the lock pin  55  on locking pin member  155  is inserted into the lock pin bores  66 ,  67  on the upper and lower cam members  24 ,  22  and a lock shaft extends through a pair of apertures  171 ,  173 , or  172 ,  174  on arms  156 ,  157  of lock pin member  155 . 
     FIG. 14 is an exploded view of an embodiment of the invention used as a quick clamping device to hold snowmobile skis on a trailer. 
     In this embodiment a shaft  40  passes through the center of lower cam member  22 . Lower cam member  22  has aperture  118  for engaging bar  18 . The shaft  40  also passes through bar  18 . Upper cam member  24  engages lower cam member  22 . The upper cam member has a handle  26  secured thereto with screws  57 . One of the screws  57  has a tether  58  extending from the screw  57  to an aperture in locking pin member  155 , to ensure it does not get separated from the handle  26 . 
     A safety pin  175  or a lock can be used to secure the locking pin member  155  to the handle  26  to ensure the locking pin  55  stays inside of the upper and lower cam members  24 ,  22  to prevent rotation of one relative to the other. 
     A washer  56  placed on shaft  40  will engage upper cam member  24  and adjustment nut  54  will adjust the shaft  40  height relative the upper cam member  24 . A locking nut  53  on shaft  40  will fix the adjustment nut on the shaft  40 . 
     The shaft  40  has a squared portion  43  at its lower end and a pin  42  therethrough for engaging a coupler  46 . The coupler has a shaft  199  on which is placed a first washer  186  and a second washer  187  securing the shaft to a trailer or other object. A nut  188  and a locking nut  189  secure the shaft  199  and coupler  46  to a trailer or other object. 
     In another embodiment the lower cam member  22  can be built into a lid and shaft  40  is inserted into a coupler  46  attached to a container such that the lid is tightly secured to the container by turning the upper cam member to the extended position. 
     Many other embodiments of the rotatable ramp jack  150  for quickly clamping one object to another or raising and lowering objects using the upper and lower cam members  24  and  22 . The extension and retraction of the upper and lower cam members  24 ,  22  using their ramp surfaces provides a simple leverage device for translation of radial force to axial force. No moving parts are used. The upper and lower cam members  24 ,  22  may be made of lightweight strong materials with low coefficients of friction such as nylon which have slippery surfaces. 
     It is preferred to have three ramps in the upper and lower cam members  24 ,  22  such that the bearing member  100  is secured into bore  130  to maintain centricity with respect to the upper and lower cam members  24 ,  22 . With three ramps the spacing can be adjusted such that a quarter revolution of the handle  26  fully extends or retracts the cams. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.