Patent Publication Number: US-6705135-B2

Title: Excavator lock

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Serial No. 60/363,274, filed Mar. 11, 2002. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to anti-theft devices for vehicles. More specifically, the invention is an anti-theft device to prevent unauthorized control and use of a mechanical excavator. 
     2. Description of the Related Art 
     The related art of interest describes various locking devices, but none discloses the present invention. There is a need for a locking device that prevents the theft of a mechanical excavator even if a thief has an ignition key to start up the excavator&#39;s engine. 
     Excavators are vulnerable to misuse and theft, particularly at night when excavators are often left unattended on construction sites. Thieves often have little difficulty in illicitly starting up an unattended mechanical excavator with or without an engine ignition key. Once a mechanical excavator&#39;s engine is running the excavator may be driven onto a trailer or flat bed truck and stolen. Such thefts lead to higher insurance premiums which inevitably translate into higher construction costs. 
     Several efforts have been made to address these problems. U.S. Pat. No. 4,653,296 issued Mar. 31, 1987 to T. Kajikawa describes a handle locking mechanism for vehicles. The &#39;296 device is adapted to secure a steering shaft operably connected to a pair of bike like handles. Whatever the merits of the &#39;296 patent there is no teaching or suggestion of a device to prevent theft of a mechanical excavator. 
     U.S. Pat. No. 5,042,754 issued Aug. 27, 1991 to R. Heath describes a device for securing the throttle control levers of an aircraft in their closed position. The &#39;754 device is useful in preventing vertical motion of the aircrafts key controls thus preventing the aircraft from leaving the ground. The &#39;754 patent does not teach or suggest a device to prevent theft of a mechanical excavator. 
     U.S. Pat. No. 5,347,835 issued Sep. 20, 1994 to D. L. Dewey describes a device for locking a control lever, such as a clutch control lever, on a handlebar of a vehicle such as a motor cycle. Whatever the merits of the &#39;835 device it is not adapted to securing the forward and reverse control levers of a mechanical excavator which are very different from those of a vehicle with handlebars. Specifically, the &#39;835 patent does not teach or suggest a device that locks the forward and reverse control levers of a mechanical excavator. 
     U.S. Pat. No. 5,359,868 issued Nov. 1, 1994 to F. L. Villani describes several devices including a device for preventing the movement of a floor-mounted gear shift lever of an automobile, and a gas pedal lock. Whatever the merits of the &#39;868 patent it does not teach or suggest an apparatus or method for securing the control levers of a mechanical excavator which are very different from those of an automobile. Specifically, the &#39;868 does not teach or suggest a device that locks the forward and reverse control levers of a mechanical excavator. 
     U.S. Pat. No. 5,829,282 issued Nov. 3, 1998 to D. G. Surridge describes a control lever lock assembly for preventing accidental activation of a coupling apparatus for controlling the coupling and decoupling of a tool attached to work machines such as a wheel loader. The &#39;282 device is not designed to prevent the theft of the work vehicle. 
     U.S. Pat. Nos. 5,911,391, 5,953,941, and 6,116,065 each describe an apparatus for locking aircraft controls and the like; and U.S. Pat. No. 5,906,121 describes a pedal lock for vehicles. The &#39;391, &#39;941, &#39;065, and &#39;121 patents do not teach or suggest a device that locks the forward and reverse control levers of a mechanical excavator. 
     None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus, an excavator lock solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The present invention is an excavator lock adapted to limit the motion of a pair of control levers such as the forward and reverse drive control levers of a mechanical excavator thereby preventing the theft of a mechanical excavator. The excavator lock comprises a main body and a locking plate. The main body has a first and second channels adapted to accommodate a first and second control levers of a mechanical excavator. The locking plate is adapted to cover the first and second channels. A locking mechanism attached to the main body actively engages with the locking plate to temporarily lock the main body to the lock plate thereby providing an excavator lock for limiting the motion of a first and second control levers of a mechanical excavator to inhibit theft of the mechanical excavator. Accordingly, it is a principal object of the invention to provide a device to prevent the theft of a mechanical excavator. 
     It is a further object of the invention to provide an excavator lock which limits the relative motion of the forward and reverse drive control levers of a mechanical excavator to thereby prevent the theft of the vehicle. 
     It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes. 
     These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective environmental view of an excavator lock according to the invention. 
     FIG. 2A shows a perspective view of a main body member with generally rectangular channels, and a lock plate member according to one embodiment of the excavator lock of the present invention. 
     FIG. 2B is a perspective view of an excavator lock with channels of generally semi-circular cross section. 
     FIG. 3A shows a perspective view of a main body member with generally rectangular channels coupled to a locking plate. 
     FIG. 3B shows a perspective view of a main body member with channels of generally semi-circular cross section coupled to a locking plate. 
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is directed to an excavator lock to help prevent theft of a mechanical excavator. More specifically, the excavator lock of the invention limits the motion of two control levers, e.g. a forward and reverse drive levers, thereby preventing the theft of the mechanical excavator. 
     Referring to the figures in general, the excavator lock is denoted by the reference numeral  300  as a whole. The excavator lock  300  comprises two parts, a main body  310  and a lock plate  320 . The main body  310  reversibly mates with the larger lock plate  320  as shown in FIG.  2 A. The main body  310  and lock plate  320  are preferably made of steel, but any material of high durability may be used. 
     FIG. 1 shows an environmental perspective view of the excavator lock  300 . The excavator lock  300  is attached to, and thereby immobilizing, a first control lever  330   a  and a second control lever  330   b . The levers  330   a  and  330   b , which are shown for illustrative purposes only and are not intended to limit the scope of the present invention; the excavator lock  300  of the present invention can be used to immobilize any pair of control levers that align in the manner shown in FIG. 1 with regard to current and future mechanical excavators. In addition, it should be understood that the excavator lock  300  can be fitted to the illustrated levers so that the levers  330   a  and  330   b  are clamped in channels  350   a  and  350   b , respectively. 
     It is well known in the art of handling mechanical excavators that the control levers  330   a  and  330   b  are pivotally attached to an excavator (not shown). When the control levers  330   a  and  330   b  are generally aligned as shown in FIG. 1, they adopt a generally converging angle  335 . As will become clear below, the excavator lock  300  is adapted to accommodate the convergence angle  335  of the control levers  330   a  and  330   b.    
     Referring to FIGS. 2A and 2B, a lock mechanism  322  is shown installed in an external face  324   a  of the main body  310 . The lock mechanism  322  comprises a stock  322   b  (shown in phantom in FIG. 2B) terminating in a lock-bolt  322   c  which emerges from the interior face  324   b . An optional recessed section  328  is shown in the inner face  324   b  of the main body  310 . The lock mechanism  322  is preferably a spring biased lock and preferably adapted to function with a pick resistant key  326 . It should be understood that the lock mechanism  322  may vary and take any suitable form and may incorporate, for example, a keyless combination lock in cooperative communication with a lock-bolt  322   c ; therefore, the lock mechanism  322  is shown for illustrative purposes only and should not be viewed as limiting the present invention in any way. 
     With respect to FIG. 2A, the interior of the main body  310  comprises opposite ends  340   a  and  340   b  respectively defining converging channels  350   a  and  350   b ; the channels  350   a  and  350   b  are of generally rectangular cross-section. The channel  350   a  comprises parallel outer  360   a  and inner  370   a  sides, and a rear facing side  380   a . The channel  350   b  comprises parallel outer  360   b  and inner  370   b  sides and a rear facing side  380   b . Optional spacers  392   a  and  392   b  may be fitted, as shown, as optional liners respectively in converging channels  350   a  and  350   b.    
     Referring to both FIGS. 2A and 2B, the main body  310  further comprises an interior face  324   b  of generally trapezoidal shape defined by converging sides  370   a  and  370   b , and opposite parallel sides  390  and  400 , wherein side  390  has a greater length than side  400 . Since sides  370   a  and  370   b  are converging it follows that the channels  350   a  and  350   b  must also be converging at an angle  335  (see FIG.  1 ). 
     It will be understood that the magnitude of the converging angle  335  may vary according to the degree of convergence of pairs of levers  330   a  and  330   b  found in excavator trucks. It should also be understood that while it is preferred that the lock plate  320  has a lengthwise trapezoidal shape, the lock plate  320  can be rectangular in shape or any other shape providing that the lock plate  320  covers the channels  350   a  and  350   b  in order to immobilize the controlling levers  330   a  and  330   b.    
     A plate  410 , which forms part of the lock mechanism  322 , is set into the recessed section  328 . The plate  410  is fastened to the main body  310  by fasteners such as security hex screws  420   a  and  420   b . Depressing the lock mechanism  322  inward causes the lock-bolt  322   c  to emerge through a hole defined in the plate  410  and emerge from the recessed section  328  to engage a blind hole  450   a  in the lock plate  320  to reversibly prevent the main body  310  moving relative to the lock plate  320 . It should be understood that the terms “reversible” and “reversibly” are intended to mean that the action can be reversed, e.g., by manipulating the position of the lock-bolt  322   c  with respect to the blind hole  450   a  (or  450   b , see FIG.  2 B and explanation below) the main body  310  can be repeatedly locked to and unlocked with respect to the lock-plate  320 . 
     The lock plate  320  comprises opposite L-shaped ends  430   a  and  430   b  and a back-plate  440 ; the L-shaped ends  430   a  and  430   b  are preferably attached by welds  315  to the back-plate  440 . The blind hole  450   a  comprises a hole drilled through the back-plate  440  and a portion of an L-shaped bracket  460  which covers the hole in the back-plate  440  to provide the blind hole  450   a . The L-shaped bracket  460  serves to prevent a putative thief from interfering with the lock-bolt  322   c . In addition, one end  462  of the L-shaped bracket  460  acts as a stop when the main body  310  reversibly mates with the lock plate  320 . An optional stop  470  may be attached to the main body  310  to stop against a top ledge  442  of the back-plate  440 . 
     In use, an operator (such as an excavator driver or owner) aligns the control levers of interest as represented herein by levers  330   a  and  330   b  and maneuverers them into the channels  350   a  and  350   b  of the main body  310 . The locking plate  320  is maneuvered until the L-shaped ends  430   a  and  430   b  are wrapped around the levers  330   a  and  330   b  at a position just below the main body  310 , and the locking plate  320  is lifted up to reversibly mate with the main body  310 ; a reversibly mated (i.e. docked) main body  310  and lock plate  320  is shown in FIG.  2 B. The locking mechanism  322  is operated to cause the lock-bolt  322   c  to engage the blind hole  450   a  thus locking the main body  310  to the lock plate  320  whereby the levers  330   a  and  330   b  are immobilized in channels  350   a  and  350   b  thereby inhibiting the theft of an excavator. To release the excavator lock  310  from the locking plate  320  the locking mechanism  322  is operated to retract the lock-bolt  322   c  from the blind hole  450   a  thereby freeing the main body  310  which can be moved from the lock plate  320  to expose the channels  350   a  and  350   b  to free the levers  330   a  and  330   b . It will be understood that an operator could use the excavator lock  300  in a variety of ways to immobilize and release the levers  330   a  and  330   b.    
     Referring to FIGS. 3A and 3B, a further embodiment of the excavator lock  300  is shown comprising channels  350   c  and  350   d , which are adapted to accommodate the control levers  330   a  and  330   b . The channels  350   c  and  350   d  are generally of semi-circular cross section in contrast to the channels  350   a  and  350   b  which were generally of rectangular cross section. The channels may be of any other suitable cross section shape that can accommodate the stems of the control levers  330   a  and  330   b.    
     Referring to FIGS. 2B and 3B, the blind hole  450   b  partly penetrates the back-plate  440  thereby rendering redundant the L-shaped bracket  460 . The optional stop  470  acts as a stop against the lock plate  320 , and more particularly the ledge  442  of the back-plate  440 . It should be understood that the stop functions of the L-shaped brackets  460  and  470  are optional, i.e. they may be left out, because they are not essential for the working of the excavator lock  300  according to the present invention. The invention includes other permutations that might be found in U.S. Provisional Patent Application Serial No. 60/363,274. U.S. Provisional Patent Application Serial No. 60/363,274 is incorporated herein by reference in its entirety. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.