BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the general art of land vehicles, and to the particular field of accessories for land vehicles. 
   2. Discussion of the Related Art 
   During a traffic stop of a vehicle by a law enforcement officer, the officer generally pulls his car up behind the car being stopped. The officer then exits his car and approaches the stopped car. This is entirely routine. Generally, the driver of the stopped vehicle waits in his or her car to speak with the officer. Again, this is part of a routine traffic stop. 
   However, in some isolated instances, the driver of the stopped vehicle does not wish to speak with the officer. In some instances, the driver of the stopped car attempts to flee by driving away from the traffic stop. This can engender a high speed automobile chase which can be dangerous. Even when an officer has identified the fleeing car and may even have assistance, the fleeing car can be dangerous. 
   Therefore, there is a need for a means to prevent a driver of a car that has been stopped by a law enforcement officer during a traffic stop from fleeing from the law enforcement vehicle. 
   In order to be as safe as possible, the officer should be able to take as many precautions as possible before he exits his vehicle. This should include taking steps to prevent the stopped car from fleeing while the officer checks records and takes any other precautions which are required for traffic stops. 
   Therefore, there is a need for a means to prevent a car that has been stopped by a law enforcement officer during a traffic stop from fleeing from the law enforcement vehicle and which can be activated before the officer exits his vehicle. 
   If an officer suspects that the driver of a stopped vehicle may attempt to flee, the officer may sometimes take steps to prevent this. Presently, these steps include parking the officer&#39;s vehicle in a location with respect to the stopped vehicle which blocks movement of the stopped vehicle. However, such position may place the officer in danger as he exits his car and may locate the officer&#39;s car in a less than desirable position with respect to the stopped car and/or by-passing traffic. 
   Still further, it would be advantageous if the driver of a stopped car can be prevented from fleeing without endangering the officer&#39;s car. If the officer&#39;s car is blocking the path of the stopped car, the officer&#39;s car may be damaged by the stopped car if flight is attempted. 
   Therefore, there is a need for a means to prevent the driver of a car that has been stopped by a law enforcement officer during a traffic stop from fleeing from the law enforcement vehicle wherein the means can be activated before the officer exits his vehicle and in a manner that prevents flight of the driver of the stopped car without endangering the officer&#39;s car. 
   Still further, any device which can assist an officer during a traffic stop should be amenable to rapid and easy deployment. The officer must be able to focus his entire attention on the procedure associated with the stop and should not be distracted by complex or cumbersome steps required to deploy an accessory. 
   Therefore, there is a need for a means to prevent a driver of a car that has been stopped by a law enforcement officer during a traffic stop from fleeing from the law enforcement vehicle and which can be activated before the officer exits his vehicle and in a manner that prevents flight of the driver of the stopped car without endangering the officer&#39;s car and which is also capable of easy and rapid deployment without distracting the officer&#39;s attention from his tasks associated with the traffic stop. 
   PRINCIPAL OBJECTS OF THE INVENTION 
   It is a main object of the present invention to provide a means to prevent a car that has been stopped by a law enforcement officer during a traffic stop from fleeing from the law enforcement vehicle. 
   It is another object of the present invention to provide a means to prevent a driver of a car that has been stopped by a law enforcement officer during a traffic stop from fleeing from the law enforcement vehicle and which can be activated before the officer exits his vehicle. 
   It is another object of the present invention to provide a means to prevent a driver of a car that has been stopped by a law enforcement officer during a traffic stop from fleeing from the law enforcement vehicle wherein the means can be activated before the officer exits his vehicle and in a manner that prevents flight of the driver of the stopped car without endangering the officer&#39;s car. 
   It is another object of the present invention to provide a means to prevent a driver of a car that has been stopped by a law enforcement officer during a traffic stop from fleeing from the law enforcement vehicle and which can be activated before the officer exits his vehicle and in a manner that prevents flight of the driver of the stopped car without endangering the officer&#39;s car and which is also capable of easy and rapid deployment without distracting the officer&#39;s attention from his tasks associated with the traffic stop. 
   SUMMARY OF THE INVENTION 
   These, and other, objects are achieved by an accessory for use on a law enforcement vehicle which quickly places tire-piercing spikes adjacent to at least one tire of the stopped vehicle. The spikes are positioned such that should the driver of the stopped vehicle attempt to flee, the vehicle will drive over the spikes and the tire, or tires, will be flattened. The invention is thus embodied in a device for preventing a driver of an automobile from fleeing from a law enforcement vehicle after being stopped by the law enforcement vehicle and comprises a hydraulic unit adapted to be pivotally mounted on the undersurface of a law enforcement vehicle near the front end of the law enforcement vehicle, the hydraulic unit pivotally moving between a stored position and a deployed position, the hydraulic unit including a housing, a longitudinal axis of the housing, a push rod telescopingly accommodated in the housing and a wheel rotatably mounted on the push rod, the wheel being adapted to contact a ground surface adjacent to the law enforcement vehicle when the hydraulic unit is in the deployed position, the push rod being located inside the housing when the hydraulic unit is in the stored position; a biasing element connected to the push rod and biasing the push rod towards the inside of the housing; a second biasing element inside the housing; a source of fluid on the law enforcement vehicle and fluidically connected to the housing of the hydraulic unit; a tire-piercing spike unit on the hydraulic unit, the tire-piercing spike unit being movable between a stored position and a deployed position, the tire-piercing spike unit being in the deployed position when the hydraulic unit is in the deployed position, the tire-piercing spike unit including two arms having tire-piercing spikes thereon, and an actuating lever unit which movably connects each arm of the two arms to the hydraulic unit, each arm of the two arms being movable between a stored position and a deployed position, each arm of the two arms being in the deployed position when the hydraulic unit is in the deployed position; and a device control unit which includes a foot pedal located inside the law enforcement vehicle, the foot pedal being movable between a device-deploying position and a device-storing position, a lock unit on the foot pedal, a lock release in the law enforcement vehicle and connected to the lock unit, and a cable connecting the foot pedal to the housing of the hydraulic unit, the hydraulic unit being in the deployed position when the foot pedal is in the device deploying position. 
   The device embodying the present invention permits an officer to pull up behind a stopped vehicle and then to quickly and easily deploy the tire-piercing spikes to a location that will prevent the driver of the stopped vehicle from fleeing while the officer is otherwise occupied. The officer need not endanger himself or his vehicle to effectively prevent flight of the stopped vehicle and can do so without diverting his attention from the procedures associated with a traffic stop. 


   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       FIG. 1  is a perspective view of the device embodying the present invention. 
       FIG. 2  is an elevational view taken along line  2 — 2  of FIG.  1 . 
       FIG. 3  shows a device control unit used in the device embodying the present invention. 
       FIG. 4  illustrates a hydraulic version of the device embodying the present invention. 
       FIG. 5  illustrates a pneumatic version of the device embodying the present invention. 
   


   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description and the accompanying drawings. 
   Referring to the Figures, it can be understood that the present invention is embodied in an anti-escape mechanism  10  for use by law enforcement officers during a traffic stop to prevent a driver of a stopped car from fleeing. Device  10  comprises a first hollow tubular housing  12  which has a first end  14 , a second end  16 , and a longitudinal axis  18  which extends between the first end  14  of the first hollow tubular housing  12  and the second end  16  of the first hollow tubular housing  12 . A blind-ended bore  20  is defined between the first end  14  of the first hollow tubular housing  12  and the second end  16  of the first tubular housing  12 . An inner surface  22  is located adjacent to the blind-ended bore  20 . The inner surface  22  of the first hollow tubular housing  12  has an internal dimension  24 . Housing  12  further includes an outer surface  26  which has an outer dimension  28 . 
   A seal element  30  is mounted on the inner surface  22  of the first hollow tubular housing  12  adjacent to the second end  16  of the first hollow tubular housing  12 . An end cap  32  is on the first end  14  of the first hollow tubular housing  12 . 
   A fluid valve  34  is mounted on the first hollow tubular housing  12  adjacent to the first end  14  of the first hollow tubular housing  12 . The fluid valve  34  is in fluid communication with the blind-ended bore  20  for a purpose that will be understood from the teaching of the following disclosure. 
   A pivot connection element  40  (see  FIG. 3 ) is located on the first hollow tubular housing  12  adjacent to the first end  14  of the first hollow tubular housing  12 . The pivot connection element  40  is adapted to pivotally connect the first hollow tubular housing  12  to an underneath surface US of a law enforcement vehicle V. The first hollow tubular housing  12  is pivotally movable between a stored position SP with the second end  16  of the first hollow tubular housing  12  located adjacent to the underneath surface of the law enforcement vehicle and a deployed position DP, shown in solid lines in  FIG. 3 , with the second end  16  of the first hollow tubular housing  12  located spaced apart from the underneath surface of the law enforcement vehicle. 
   A second hollow tubular housing  50  includes a first end  52 , a second end  54 , and a longitudinal axis  56  which extends between the first end  52  of the second hollow tubular housing  50  and the second end  54  of the second hollow tubular housing  50 . The longitudinal axis  56  of the second hollow housing  50  is co-linear with the longitudinal axis  18  of the first hollow tubular housing  12 . 
   A blind-ended bore  58  is defined between the first end  52  of the second hollow tubular housing  50  and the second end  54  of the second tubular housing  50 . An inner surface  60  is located adjacent to the blind-ended bore  58  of the second hollow tubular housing  50 . The inner surface  60  of the second hollow tubular housing  50  has an internal dimension  62 . The second housing  50  further includes an outer surface  64  which has an outer dimension  66 . Outer dimension  66  of the second hollow tubular housing  50  is smaller than inner dimension  24  of the first hollow tubular housing  12 . The outer surface  64  of the second hollow tubular housing  50  slidingly engages a ledge  67  on which seal element  30  is mounted adjacent to the second end  16  of the first hollow tubular housing  12 . 
   An end cap  70  is located on the first end  52  of the second hollow tubular housing  50 . End cap  70  on the first end  52  of the second hollow tubular housing  50  has fluid passages  72  defined therethrough. The fluid passages  72  of the second hollow tubular housing  50  fluidically connect blind-ended bore  20  of the first hollow tubular housing  12  to blind-ended bore  58  of the second hollow tubular housing  50 . 
   A housing stop  74  is located on the end cap  70  of the second hollow housing  50 . The housing stop  74  extends outward from the end cap  70  of the second hollow housing  50  towards the inner surface  22  of the first hollow tubular housing  12 . A stop element  76  is mounted on the inner surface  60  of the second hollow tubular housing  50  adjacent to the second end  54  of the second hollow tubular housing  50 . 
   The second hollow tubular housing  50  is telescopingly accommodated in the first hollow tubular housing  12  and moves between a closed position CP with the end cap  70  on the first end  52  of the second hollow tubular housing  50  located adjacent to the end cap  32  on the first end  14  of the first hollow tubular housing  12  and an open position OP, shown in  FIG. 2  in solid lines, with the housing stop  74  on the end cap  70  of the second hollow housing  50  abutting the seal element  30  mounted on the inner surface  22  of the first hollow tubular housing  12  adjacent to the second end  16  of the first hollow tubular housing  12 . 
   Device  10  further includes a fluid chamber  80  defined in the blind-ended bore  20  of the first hollow tubular housing  12  between the inner surface  22  of the first hollow tubular housing  12  and the outer surface  64  of the second hollow tubular housing  50 . The fluid chamber  80  is fluidically connected to the fluid valve  34  mounted on the first hollow tubular housing  12 . 
   A return spring  82  is mounted on the end cap  32  on the first end  14  of the first hollow tubular housing  12 . The return spring  82  has a first end  84  fixed to the end cap  32  on the first end  14  of the first hollow tubular housing  12  and a second end  86  fixed to the end cap  70  on the first end  52  of the second hollow tubular housing  50 . The return spring  82  biases the second hollow tubular housing  50  towards the closed position. 
   A push rod  90  is located in the blind-ended bore  58  of the second hollow tubular housing  50 . The push rod  90  includes a first end  92 , a second end  94 , and a longitudinal axis  96  which extends between the first end  92  of the push rod  90  and the second end  94  of the push rod  90 . Longitudinal axis  96  of the push rod  90  is co-linear with longitudinal axis  56  of the second hollow tubular housing  50 . 
   Push rod  90  further includes an outer surface  100  which has an outer dimension  102  which is smaller than the inner dimension  62  of the second hollow tubular housing  50 . 
   A stop element  104  is located on the first end  92  of the push rod  90 . Stop element  104  extends outwardly from the outer surface  100  of the push rod  90  towards the inner surface  60  of the second hollow tubular housing  50 . 
   Push rod  90  is telescopingly accommodated in the second hollow tubular housing  50  and moves between a stored position PSP with the end cap on the first end  92  of the push rod  90  located adjacent to the end cap  70  on the first end  52  of the second hollow tubular housing  50  and an extended position PEP with the stop on the end cap of the push rod  90  abutting the stop element  76  mounted on the inner surface  60  of the second hollow tubular housing  50  adjacent to the second end  54  of the second hollow tubular housing  50 . 
   A wheel unit  110  is mounted on the second end  94  of the push rod  90  for movement therewith. Wheel unit  110  includes a U-shaped wheel mount  112  which has a bight section  114  fixedly mounted on the second end  94  of the push rod  90  and further includes two legs  116  and  11 B attached to the bight section  114  and which extends with the push rod  90  in the direction of the longitudinal axis  96  of the push rod  90 . The wheel unit  110  further includes a wheel axle  120  mounted on the legs  116 ,  118  of the wheel mount  112  and which extends transversely to the longitudinal axis  96  of the push rod  90 . 
   A wheel  122  is rotatably mounted on the axle  120  to rotate around the axle  120 . Wheel  122  is formed of hard rubber and is adapted to rotationally engage a ground surface GS when the push rod  90  is in the extended position and the second hollow tubular housing  50  is in the open position and the first hollow tubular housing  12  is in the deployed position. 
   A calibrated spring  130  encircles the push rod  90 . The calibrated spring  130  has a first end  132  which contacts the stop element  104  on the first end  92  of the push rod  90  and a second end  134  which contacts stop element  76  mounted on the inner surface  60  of the second hollow tubular housing  50  adjacent to the second end  54  of the second hollow tubular housing  50 . Calibrated spring  130  biases the push rod  90  towards the stored position. Calibrated spring  130  has a spring force that is greater than the spring force of return spring  82 . 
   A source  140  of fluid is fluidically connected to the fluid valve  34  on the first hollow tubular housing  12 . Source  140  of fluid has a fluid pressure which is greater than the pressure exerted on the end cap on the push rod  90  from the calibrated spring  130  and greater than the pressure exerted on the end cap  70  of the second hollow tubular housing  50  from the return spring  82 . The fluid can be either hydraulic as shown in  FIG. 4  as device  10 H with a hydraulic fluid tank TH in the vehicle and a hydraulic pump PH also in the vehicle, which are connected together and to the housings  12 ,  50  via hydraulic hoses H 1  and H 2 , or pneumatically as shown in  FIG. 5  as device  10 P which includes an air compressor AC fluidically connected to the housings  12 ,  50  by an air hose AH. Those skilled in the art will understand the fluid circuits and fluid elements needed for these systems. Accordingly, the details of such fluid circuits will not be presented in detail. 
   Thus, the return spring  82  is calibrated to a tension greater than the force required to pull the second hollow tubular housing  50  into a collapsed position with no pressure on the unit. The pressure calibrated spring  130  on the push rod  90  is calibrated to a tension greater than the force required to push the second hollow tubular housing  50  into the extended position, but less than the force of the created fluid pressure. 
   The table below is an example of the pressures which will achieve the stated purposes of device  10 . 
   
     
       
             
           
             
             
             
           
         
             
                 
             
             
               Example (scale of 1 to 10 psi) 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
                 
               Force of fluid going into the system 
               10 psi  
             
             
                 
               Force needed to pull the second housing 
               4 psi 
             
             
                 
               to a collapsed position with no 
             
             
                 
               pressure in the system 
             
             
                 
               Spring force of the return spring 
               5 psi 
             
             
                 
               Spring force of the pressure calibrated spring 
               8 psi 
             
             
                 
                 
             
           
        
       
     
   
   Thus, since the springs  82 ,  130  are of different spring forces, the housings  12 ,  50  will move when pressure is applied. The pressure going into the housings  12 ,  50  is greater than the forces of both springs  82 ,  130 . The return spring  82  force is less than the inner push rod spring force, but both spring forces are less than the pressure of the fluid going into the system. Fluid flow directions are indicated in  FIG. 2  by arrows F. The differential pressures and different spring forces cause the push rod and the housings  12 ,  50  to move relative to each other for the purpose of operating the device  10  as will be understood from the teaching of this disclosure. 
   Device  10  further includes a tire-piercing spike unit  150 . Unit  150  includes two identical wing elements,  152  and  154 . Each wing element  152 ,  154  includes a first pivot connection  156  mounted on the push rod  90  for movement therewith and a second pivot connection  158  mounted on the second end  54  of the second hollow tubular housing  50  for movement therewith. The first pivot connection  156  moves relative to the second pivot connection  158  as the push rod  90  moves relative to the second hollow tubular housing  50 . 
   Each wing element  152 ,  154  further includes a first arm element  160  having a proximal end  162 , pivotally connected to the first pivot connection  156 , and a distal end  164  spaced apart from the outer surface  100  of the push rod  90 . First arm element  160  is pivotally movable between a stored position, shown in  FIG. 2 , with the distal end  164  of the first arm element  160  located adjacent to the outer surface  100  of the push rod  90  and a deployed position indicated in  FIG. 1  by dotted lines  152 ′, with the distal end  164  of the first arm element  160  spaced apart from the outer surface  100  of the push rod  90 . 
   A second arm element  170  has a proximal end  172 , which is pivotally connected to the second pivot connection  158 , and a distal end  174 , which is spaced apart from the outer surface  64  of the second hollow tubular housing  50 . The distal end  174  of the second arm element  170  is pivotally connected to the distal end  164  of the first arm element  160 . The second arm element  170  is pivotally movable between a stored position PAS shown in solid lines in  FIG. 1 , with the distal end  174  of the second arm element  170  located adjacent to the outer surface  26  of the first hollow tubular housing  12  and a deployed position PAD indicated in  FIG. 1  by dotted lines, with the distal end  174  of the second arm element  170  spaced apart from the outer surface  26  of the first hollow tubular housing  12 . 
   A spiked arm  180  of each wing element  152 ,  154  has a proximal end  182 , pivotally connected to the distal end  174  of the second arm element 170 , and a distal end  184 . The spiked arm  180  is pivotally movable between a stored condition SS, shown in solid lines in  FIG. 1 , wherein the spiked arm  180  is oriented to extend in the direction of the longitudinal axis  18  of the first hollow tubular housing  12 , and a stored position SD, shown in solid lines in  FIG. 1 , wherein the spiked arm  180  is oriented to extend transversely to the longitudinal axis  18  of the first hollow tubular housing  12 . The spiked arm  180  further includes a multiplicity of tire-piercing spikes, such as tire-piercing spike  186  thereon. The spiked arm  180  is in the deployed condition when the push rod  90  is in the extended position and the second hollow tubular housing  50  is in the open position and the first hollow tubular housing  12  is in the deployed position. 
   A device control unit  190  is mounted on the law enforcement vehicle and is shown in FIG.  3 . Unit  190  includes a foot pedal unit  192 , which includes a foot pedal  194 , a pedal arm  196 , which has a proximal end  198  and a distal end  200  with the foot pedal  194  being mounted on the distal end  200  of the pedal arm  196 . The foot pedal  194  is located inside the motor vehicle and is operated in the manner of an emergency brake. 
   A pivot element  202  pivotally connects the proximal end  198  of the pedal arm  196  to the law enforcement vehicle. The pedal arm  196  is pivotally movable between a device-storing position PSP, indicated in dotted lines in  FIG. 3 , and a device-deploying position DDP shown in solid lines in FIG.  3 . 
   A lock unit  210  is located on the pedal arm  196  and locks the pedal arm  196  in position. 
   A pedal arm spring  212  has a first end  214  connected to the law enforcement vehicle and a second end  216  connected to the pedal arm  196 . Pedal arm spring  212  biases the pedal arm  196  toward the device-deploying position. 
   A lock unit release unit  220  is movably mounted on the law enforcement vehicle and has a first end  222  connected to the lock unit  210  and a second end  224  located inside the law enforcement vehicle. The lock unit  210  is movable between a locking position LP, shown in solid lines in FIG.  3 , in which the lock unit  210  is locked and an unlocking position ULP, indicated in dotted lines in  FIG. 3 , in which the lock unit  210  is unlocked and free to move between the device-storing position and the device-deploying position. The lock unit  210  includes a knob  226  located inside the vehicle. 
   A cable  230  has a proximal end  232 , fixedly connected to the pedal arm  196  for movement therewith, and a distal end  234  fixedly connected to the first hollow tubular housing  12  to move the first tubular hollow housing  12  from the deployed position towards the stored position as the pedal arm  196  moves from the device-deploying position towards the device-storing position and to allow the first hollow tubular housing  12  to move towards the deployed position as the pedal arm  196  moves towards the device-deploying position. 
   The device control unit  190  can thus be operated in the manner of an emergency brake. The officer can release the unit using the lock unit release unit  220  without taking his eyes off the stopped vehicle or distracting his attention from the procedures associated with the traffic stop by simply pulling on the knob  226  in the manner of an emergency brake release, and can reset the unit using the foot pedal  194 , again without taking his eyes off the stopped vehicle. 
   The device  10  embodying the present invention can include sensors that will stop deployment of the device  10  as soon as the spikes are located adjacent to the tires of the stopped vehicle. The sensors can utilize lasers or the like and will be connected to the fluid source to automatically stop fluid flow when the tire-piercing spikes reach the desired location. The tire-piercing spikes are removed after the traffic stop is completed by simply releasing the lock unit  210  using knob  226  in the manner of an emergency brake. It is understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangements of parts described and shown.
A device is mounted on a law enforcement vehicle and is deployed by a law enforcement officer after the officer has pulled the law enforcement vehicle up behind a vehicle being stopped. The device has tire-piercing spikes thereon which are located adjacent to the tires of the stopped vehicle when the device is deployed. If the driver of the stopped vehicle attempts to flee, the tires of the stopped vehicle will be pierced. The device is stored beneath the law enforcement vehicle and is controlled from inside the law enforcement vehicle.