Abstract:
The present invention is directed to a lock construction for securing to a trailer socket and thereby preventing attachment of the trailer socket to a connecting member of an unauthorized towing vehicle. The lock construction comprising a base with a first upstanding member extending from the base and adapted to engage the trailer socket of the trailer. A second upstanding member is disposed on the base in spaced relation to the first upstanding member. A shaft like member is positioned in the housing and is slidable toward the first upstanding member from an unlocked position where the third member is spaced away from the first upstanding member to a locked position wherein the third member engages the trailer socket once it is attached to the first upstanding member. A locking mechanism is operative connected to the third member and to allow slidable movement of the third member. A ratchet member and a ratchet surface are also included to allow slidable movement of the third member to different locked locations.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a lock construction and particularly to a lock for securing trailers against unauthorized attachment to a trailer hitch of a towing vehicle. Conventionally, trailers are connected to a trailer hitch secured to a towing vehicle for towing the trailer behind the vehicle. The trailers are constructed with a trailer hitch socket that extends from the trailer and is attached to a connecting member, such as a ball, mounted on a towing bar secured to the towing vehicle. The connecting member is normally held in the trailer hitch socket by retractable devices that are operated by a clasp or a lever. Once the socket is fitted over the connecting member, the retractable devices engage the lower half of the member and the lever secures the retractable devices over the member. Once engaged, the retractable devices prevent the separation of the trailer from the towing vehicle until the retractable devices are released by the lever. When the trailer is not being towed, it is often disengaged from the vehicle, leaving the trailer highly susceptible to theft due to the ease of attaching the trailer socket to a trailer hitch of an unauthorized vehicle. 
     Several devices have been developed to prevent trailer theft by preventing connection of the trailer hitch socket to the trailer hitch of an unauthorized towing vehicle. U.S. Pat. No. 5,332,251 to Farquhar discloses a trailer hitch lock assembly comprising an upper bolt plate with a bolt that engages a lower shield plate. A separate padlock is used to engage a hole in the bolt to secure the bolt plate and the shield plate togther. The use of the separate padlock for securing the plates together makes the lock more difficult to operate due to the additional attachment of parts. Additionally the padlock is exposed, allowing access for tampering with the locking mechanism. 
     U.S. Pat. Nos. 4,032,171 to Allen et al. and U.S. Pat. No. 5,873,271 to Smith both disclose trailer hitch locks that are adaptable for use with a trailer having a ball shaped connecting member. The Allen trailer hitch lock discloses a separate padlock for securing the locking assembly. As in the lock disclosed in Farquhar, the Allen lock construction leaves the padlock open to tampering. Smith discloses a lock having upper and lower jaws such that the upper jaw is moveable vertically between the locked and unlocked positions. The vertical construction makes the lock difficult to operate wherein the upper jaw must be manually lifted and adjusted to accommodate different sizes of trailer sockets. 
     Accordingly, there is a need for a lock that is adaptable to different types and sizes of the socket on the trailer and provides greater ease in operation while maintaining a high level of security. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a lock construction for securing to a trailer socket and thereby preventing attachment of the trailer socket to a connecting member of an unauthorized towing vehicle. The lock construction comprises a base with a first upstanding member extending from the base and adapted to engage the trailer socket of the trailer. A second upstanding member is disposed on the base in spaced relation to the first upstanding member. A shaft like member is positioned in the housing and is slidable toward the upstanding member from an unlocked position where the shaft is spaced away from the upstanding member to a locked position wherein the shaft engages the trailer socket once it is attached to the upstanding member. A locking mechanism is operatively connected to the shaft for movemenet between a first position to release the shaft for slidable movement and a second position to prevent the shaft from slidable movement. The lock additionally includes a ratchet member and ratchet surface, allowing slidable movement of the shaft to different locked locations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a lock construction according to the present invention; 
     FIG. 2 is side view of the lock construction in FIG. 1, showing a shaft extending toward a first upstanding member to engage a trailer socket; 
     FIG. 3 is a side view of the lock construction in FIG. 1, showing the shaft away from the first upstanding member to release the trailer socket; 
     FIG. 4 is a front view of the lock construction in FIG. 1; 
     FIG. 5 is an exploded view of the lock construction in FIG. 1, showing the operating elements prior to assembly; 
     “FIG. 6 is cross-sectional view taken along line  6 — 6  of the lock in FIG.  5 .” 
     FIG. 7 is a front view of a ratchet member for the lock in FIG. 1; 
     FIG. 8 is a side view of the ratchet member for the lock in FIG. 1; 
     FIG. 9 is a side view of the ratchet surface for the lock in FIG. 1; 
     FIG. 10 is a cross-sectional view taken along line  10 — 10  of the lock construction of FIG. 6, showing the lock in a locked position; 
     FIG. 11 is a cross-sectional view taken along line  11 — 11  of the lock construction of FIG. 6, showing the lock in a ratcheting position; 
     FIG. 12 is a cross-sectional view taken along line  12 — 12  of the lock construction of FIG. 6, showing the lock in an unlocked position; and 
     FIG. 13 is a perspective view of another embodiment of a lock construction according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, the lock  100  of the present invention is shown having a base  102  with first and second upstanding members  104  and  106  disposed respectively on first and second portions  108  and  110  of the base  102 . The base  102  may be constructed of any ferrous or non-ferrous material such as steel, aluminum, zinc or molded plastic. Additionally, an insert constructed of a rubber or other non-slipping materials may also be attached to the bottom side of the base to prevent slippage of the lock  100  during storage of the lock  100 . 
     The first upstanding member  104  is shown as a spherical ball similar to the ball typically used in a trailer hitch for engaging a trailer socket  112  from the trailer, as shown in FIG.  2 . The ball  104  of the present lock  100  substitutes for the connecting member of a trailer hitch that is normally welded to a tow bar of a towing vehicle. The lock  100  is secured to the trailer socket by inserting the ball  104  within the socket  112  and secured the lock thereto to prevent the attachment of the trailer socket  112  to the connecting member of an unauthorized towing vehicle. The ball  104  has an outer configuration that is shaped to match the inner configuration or cavity of the socket  112  to maximize the contact surface area between the ball  104  and the socket  1   12  and for a more secure attachment when the socket  112  is attached to the ball  104 . 
     “The second upstanding member  106  is in the form of a lock housing and is disposed on the second portion  110  of the lock  100  for retaining the operating elements of the lock  100 . A shaft like member  114  is slidable from the housing  106  toward the ball  104 , as shown in FIG. 2, to a locked position for securing an object such as a trailer socket  112  between the shaft  114  and the ball  104 . The shaft  114  is slidable away from the ball  104 , as shown in FIG. 3, to an unlocked position for releasing the socket  112 . Preferably, the tip  116  of the shaft  114  is shown as having a spherical recess matching the outer surface of the ball  104 , as shown in FIG.  1 . Similar to the outer configuration of the ball  104 , the spherical recess of the shaft tip  116 , with a shape to match the outer surface of the socket  112 , further increases the surface area of contact with the socket  112  and thereby hence increases the security of the attachment of the trailer socket  112  between the shaft  114  and the ball  104 .” 
     Referring now to FIG. 4, a keyway  118  is located on the front of the lock  100  for inserting an authorized key to operate the lock  100 . A pivotable cover  120  is disposed over the keyway  118  to protect the lock housing  106  from dirt or other debris that may enter the lock housing  106 . In the operation of the lock  100 , the shaft  114  is movable with respect to the ball  104  when the lock  100  is in the unlocked position and is prevented from movement when the lock  100  is in the locked position. The unlocked position additionally includes two different operational positions, a releasing position where the shaft  114  is permitted to move toward and away from the ball  104 , and a ratcheting position where the shaft  114  is only permitted to move toward the ball  114  to different lock locations. Accordingly, the lock  100  has three operational positions, locked, ratcheting and releasing. These operational positions are accomplished by the insertion of the authorized key into the keyway  118  and rotating the key to the desired position, the details of which will be discussed in greater depth hereinafter. 
     Markers  122 ,  124  and  126  are disposed on the front of the lock  100  for visually assisting the user in locating these operation positions. Marker  122  marks the key position for locating the lock  100  in the locked position. Marker  124  marks the key position for locating the lock  100  in the ratcheting position. Finally, Marker  126  marks the key position for locating the lock  100  in the releasing position. With the various operation positions so marked, the operation of the lock  100  is greatly simplified since the user needs only to insert and rotate the authorized key to the marked location for performing the desired operation of the lock  100 . 
     The operating elements of the lock  100  are shown unassembled in FIG.  5  and assembled in FIG.  6 . The lock housing  106  defmes an interior cavity  128  having a longitudinal axis  130  extending therethrough. The operating elements, including the shaft  114 , a locking mechanism  132 , a ratchet member  134 , and a ratchet surface on a ratchet type plate  136 , are received within the interior cavity  128  of the lock housing  106 . The shaft  114  includes a shaft cavity  138  for receiving the lock mechanism  132  and the rachet member  134 . The shaft  114  further includes an elongated groove  140  for receiving a pin  142 . The pin  142  is inserted through a pin recess  144  disposed on the housing  106  for securing the shaft  114  to the housing  106 . When inserted, the pin  142  engages the elongated groove  140  on top of the shaft  114 , limiting the sliding movement of the shaft  114  toward and away from the ball  104  as the pin  142  travels the length of the groove  140 . 
     The locking mechanism  132  includes a lock cylinder  146 , which is shown in FIG. 5 as a conventional wafer lock assembly having a plurality of wafers that are fitted for the authorized key. Other locking mechanisms, such as pin tumblers or electronic access mechanisms may also be used. A protrusion  148 , in the shape of a finger, extends from the lock cylinder  146  for engaging the ratchet member  134 . A groove  150  is disposed partially around the outer perimeter of the lock cylinder  146  proximal to the finger  148  for receiving a retaining clip  152 . A slot  154  extends from the top surface of the shaft  114  to the shaft cavity  138  for mounting the retaining clip  152 . The retaining clip  152  engages the groove  150  around the perimeter of the lock cylinder  146  for retaining the lock cylinder  146  within the shaft cavity  138  of the shaft  114  while allowing the lock cylinder  146  to rotate therein about the longitudinal axis  130 . 
     Referring now to FIG. 6, the shaft  114  includes a ratchet opening  158  in the shaft cavity  138  that extends from the bottom surface of the shaft  114  toward a spring recess  160  on the upper surface of the shaft  114 . The ratchet member  134  is disposed in the ratchet opening  158  of the shaft cavity  138  at a first axial location. A compression spring  156 , is received in the spring recess  160  for resiliently and downwardly biasing the ratchet member  134  in a direction perpendicular to the longitudinal axis  130 . Although a compression spring is shown in the preferred embodiment, other types of springs or biasing devices may also be used. 
     “The ratchet member  134  is generally U-shaped with a first or lower outer side  162  and a second or upper outer side  164 . The lower and upper sides  162  and  164  form lower and upper legs  166  and  168 , defining a recess  170  therebetween, as shown in FIG.  7 . The ratchet member  134  has a toothed section  172  disposed on the first side  162 , as shown in FIG. 8, for engaging a toothed section  174  of the ratchet surface  136 , as shown in FIG.  9 . The toothed section  172  of the ratchet member  134 , however, may be in the form of a pawl for engaging the tooth section  174  of the ratchet surface  136 . The spring  156  is operatively connected to the upper outer side  164  for biasing the ratchet member  134  downwardly toward the ratchet surface  136 . Accordingly, the spring  156  biases the ratchet member  134  against the ratchet surface  136  forcing the toothed sections  172  and  174  of the ratchet member  134  and ratchet surface  136  into an intermeshing engagement with each other. The lock cylinder  146  is inserted in the shaft cavity  138  at a second axial location, adjacent to the first axial location of the ratchet opening  158 , such that the finger  148  of the lock cylinder  146  is received within the recess  170  of the ratchet member  134 .” 
     The lock housing  106  includes a ratchet opening  176  extending from the base  102  to the interior cavity  128  of the lock housing  106 . The ratchet surface  136  is inserted within the lock housing  106  with the base portion fitted within the ratchet opening  176 . A plug  186  is used to secure the ratchet opening  176  from the exterior of the lock housing  106 , preventing entry of dirt or other debris. 
     FIGS. 10-12 show the details of the operation of the lock  100 . As stated previously, the lock  100  has three operating positions and these positions are located by rotating the lock cylinder  146  of the locking mechanism  132  with an authorized key to the designated location. FIG. 10 shows the lock  100  in the locked position with the locking mechanism  132  in a first engagement position with the ratchet member  134 . In the first engagement position, the finger  148  of the lock cylinder  146  is received within the ratchet recess  170  in abutting engagement with the inside surface of the lower leg  166  of the ratchet member  134 . The finger  148  thereby displaces the ratchet member  134  against the ratchet surface  136 , pressing the toothed sections  172  and  174  of the ratchet member  134  and ratchet surface  136  into an intermeshing engagement. Accordingly, the shaft  114  is prevented from movement in either direction toward or away from the ball  104 . In use, the trailer socket  112  is fitted over the ball  104 , and the shaft  114  is moved to the locked position engaging the exterior of the socket  112 . With the lock cylinder  146  in the locked position, preventing the shaft  114  from movement, the socket  112  is securely held between the ball  104  and the shaft  114 . 
     In the ratcheting position shown in FIG. 11, the locking mechanism  132  is in a second engaging position with the ratchet member  134 . In the second engaging position, the finger  148  of the lock cylinder  146  is rotated such that it is between the two legs  166  and  168  of the ratchet member  134  without vertically displacing the ratchet member  134 . Accordingly, the ratchet member  134  is pressed into engagement with the ratchet surface  136  solely by the force of the spring  156 . The ratcheting position is maintained as long as the finger  148  of the lock cylinder  146  is received in the recess  170  and does not displace the ratchet member  134  in either direction perpendicular to the longitudinal axis  130 . 
     In the ratcheting position, the configuration of the toothed sections  172  and  174  of the engaging ratchet member  134  and ratchet surface  136  allows movement of the shaft  114  in only one direction toward the ball  104  when the force applied in that direction overcomes the downward force of the spring  156 . For this purpose, each tooth of the tooth sections  172  and  174  has one angled or sloped side  178  and  180  and one straight side  182  and  184 , respectively, as shown in FIGS. 8 and 9. The toothed sections  172  and  174  of the rachet member  134  and ratchet surface  136  are configured such that a lateral force applied by the user to the shaft  114  in the direction toward the ball  104  will cause the ratchet member  134  to glide over the angled surface  184  of the toothed section  174  of the ratchet surface  136  against the downward force of the spring  156 . Lateral movement of the shaft  114  away from the ball  104  is prevented, however, due to the non-sloping surfaces  182  and  184 . 
     “The angle of the sloped surfaces  178  and  180  is selected to assist the user in pushing shaft  114  toward ball  104 , while preventing movement in the opposite direction. The angle of the sloped surfaces  178  and  180  as shown is 45°. However, other angles may be used with consideration to the compression force of the spring  156  to ensure proper operation of the lock  100  in the ratcheting position. Once in the ratcheting position, the lock  100  can be moved from the fully open and unlocked position, where the shaft  114  is disposed axially away from the ball  104 , toward the locked and closed position, where the shaft  114  is in abutting engagement with the socket  112  fitted over the ball  104 . By moving the shaft  114  toward the ball  104  along the ratchet teeth surfaces  178  and  180 , the shaft  114  is moved as necessary to properly tighten the socket  112  over the ball  104  or to accommodate different socket sizes.” 
     In the releasing position of the shaft  114 , as shown in FIG. 12, the finger  148  of the lock cylinder  146  is pressed into engagement with t he upper leg  168  of the ratchet member  134 , displacing the ratchet member  134  against t he spring  156  and disengaging the toothed sections  172  of the ratchet member  134  from the toothed section  174  of the ratchet surface  136 . In this position, the shaft  114  is completely free to move in either direction between the locked and unlocked positions toward and away from the ball  104 . Movement away from the ball  104  i s effected by pulling o n the key. Movement toward the ball  104  is effected by pushing on the shaft  114  near the outer end of the lock cylinder  146 . 
     Preferably, the compression force of the spring  156  biases the cylinder  146  towards the ratcheting position such that to effect the releasing position, the user rotates the cylinder  146  to and manually maintain the cylinder  146  at the releasing position. Accordingly, when the lock  100  is in the unlocked position, the lock  100  defaults to the ratcheting position, allowing greater ease in the operation of the lock  100 . 
     An illustrative operation of the lock  100  will now be described with respect to the preferred embodiment. To secure the lock  100  to the trailer, a user inserts an authorized key within the keyway  118  of the lock cylinder  146  and rotates the cylinder to the releasing position, marker  126 , as shown in FIG.  4 . In the unlocked position, the shaft  114  is freely moveable to and away from the ball  104 , allowing greater ease in inserting the ball  104  within the socket  112 , as shown in FIG.  2 . 
     Once the socket  112  is inserted over the ball  104  of the lock  100  and wit h the lock  100  in the releasing position, the user further secures the lock  100  by keeping the lock  100  in the releasing position a and pushing the shaft  114  toward the sock et  112  until the tip  116  of the shaft  114  abuts the exterior surface of the socket  112 . The user thereafter releases the lock, allowing the lock to default to the ratcheting position, marker  124 , such that the space between the ball  104  and the shaft  114  can be easily adjusted and tightened, depending on the particular construction and size of the trailer socket. Once the shaft  114  is tightened against the socket  112 , the user rotates the key to the locked position, marker  122 , to prevent any movement of the shaft  114 . Once in the locked position, the socket  112  is securely locked between the shaft  114  and the ball  104 . 
     Another embodiment of a lock  200  according to the present invention is shown in FIG.  13 . The locking mechanism and operation thereof are similar to the lock  100  of the previous embodiment. In place of the spherical ball  104  of the previous embodiment, a vertical block member  202  is used for insertion into the socket of the trailer. The block member  202  provides a different attachment structure for trailers having different connection mechanisms. For example, in addition to a trailer with a socket, such as shown at  112  in FIGS. 2 and 3, a trailer having a eyelet type connection may easily fit over the block member  202  for attachment thereto. The eyelet connection is shown in phantom in FIG.  13 . 
     The lock  200  additionally includes an abutment  204  that extends from the vertical block member  202 . With respect to a trailer with the socket  112  of FIGS. 2 and 3, the abutment  204  engages the inner surface of the socket to allow secure engagement therewith. The abutment  204  is additionally adaptable for use with the eyelet type socket by securing the eyelet between the abutment and the base of the lock  200 . In this situation, the shaft  206  will be moved to a locked position engaging the abutment or close enough thereto to prevent removal of the eyelet. 
     It will be appreciated that those skilled in the art may devise numerous modifications and embodiments within the scope of the present invention. It is intended that the following claims cover all such modifications and embodiments.