Abstract:
An improved, high-efficiency wheel lug nut socket is provided for use in racing pits, in order to minimize the time required for race car wheel changeovers. The socket is designed with an inner operating surface including concave surfaces and intervening apex surfaces, dimensioned so as to permit a hexagonal lug nut to be received therein with full clearance between the inner operating surface and the lug nut outer surface. The socket is normally used with a conventional high-speed pneumatic automotive wrench.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is broadly concerned with high-efficiency wheel lug nut sockets for use in racing pits in order to materially decrease pit service times for the removal and attachment of racing car wheels. More particularly, the invention is concerned with such improved wheel lug nut sockets which are designed to facilitate very rapid attachment of the sockets over wheel lug nuts for attachment or removal thereof. 
     2. Description of the Prior Art 
     During automobile races of substantial duration, race car drivers must pull their vehicles into service pits for refueling and complete wheel changes by the pit crew. Speed is of course essential in these services, else the driver will lose valuable time and race position. The limiting factor in pit servicing times is typically that required for wheel changes. In conventional practice, high-speed pneumatic wrenches are employed, such as the Ingersoll Rand “Thunder Gun,” which operates at a rotational speed of 10,000 rpm or greater. Tubular wheel lug nut sockets are secured to the wrenches, and are designed to mate with the wheel lug nuts. 
     During wheel removal, the pneumatic wrench is continually operating at high speed with the socket spinning counterclockwise, and the socket is successively applied to the wheel lug nuts for removal thereof. As the nuts are sequentially removed, the ejector spring of the socket ejects the nuts for disposal, thus clearing the socket for the next nut. After all five nuts for a given wheel are removed, the old wheel and tire are pulled from the drum studs, and a new wheel and tire are mounted on the studs. Typically, the lug nuts of the new wheel are initially adhesively applied to the outer surface of the wheel in registry with the stud openings, and once the wheel is preliminarily mounted, the wrench and socket, now spinning clockwise, are sequentially applied to the lug nuts in order to tighten the nuts on the studs to complete the wheel installation. As the socket is applied to each nut, the ejector spring is compressed within the socket. 
     The goal of every pit crew is to minimize pit service times. Inexperienced or sub-par crews are generally able to complete a service within 15-17 seconds. However, every crew seeks, in race car parlance, to “be in the twelves,” meaning that a full tire and fuel service is completed within about 12-13 seconds. As can be appreciated, the time difference between the pit service of a slow crew versus a faster crew can be very significant, especially during races requiring multiple, full-service pit stops. In this regard, the limiting factor in low pit service times is the time required for wheel replacements. 
     Conventional wheel nut sockets are plagued by a number of problems. First, the old sockets exhibit a tendency to spark and “round” the wheel lug nuts, owing to the fact that it takes 5-8 revolutions of the socket to engage and “grab” a lug nut. Also, considerable hand pressure must be exerted on the wrench to ensure that the socket is properly seated on a lug nut. Conventional sockets typically wear out every 2-3 races, requiring replacement thereof. Furthermore, these conventional sockets typically have an enlarged lip adjacent the open operating end thereof, which can engage an adjacent nut as the socket is withdrawn. 
     There is accordingly a need in the art for improved wheel lug nut sockets for use in automotive racing contexts which permit removal and replacement of automotive tires in a minimum of time. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the problems outlined above and provides a wheel lug nut socket for use in racing pits which materially decreases wheel replacement times. Generally speaking, a socket in accordance with the invention comprises an elongated, tubular socket body presenting an open, lug nut-receiving operating end and an opposed tool connection end. The operating end has an inner operating surface configured to receive a hexagonal lug nut therein and comprises a plurality of concave surfaces in spaced relationship to each other with an apex surface between each pair of side-by-side concave surfaces. The lug nut has an outer surface comprising six wrench flat surfaces with an apex between each side-by-side pair of wrench flat surfaces. The inner operating surface of the socket is configured and dimensioned to permit the hexagonal lug nut to be received within the socket with full clearance between the inner operating surface and the lug nut outer surface; as or after the rotating socket is seated over the lug, the socket engages the lug nut flats in order to rapidly remove or attach a lug nut, depending upon the direction of socket rotation. 
     Normally, the operating surface of the socket comprises six side-by-side and identical concave surfaces with identical, substantially flattened apex surfaces between each side-by-side pair of concave surfaces. 
     Use of the improved sockets of the invention permits rapid placement of lug nuts in a racing pit environment, so that total pit service times are minimized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a conventional prior art wheel lug nut socket, viewing the enlarged, operating end of the socket, and depicting the standard internal lug nut ejector spring within the socket; 
         FIG. 2  is a vertical sectional view of the prior art socket; 
         FIG. 3  is a vertical sectional view similar to that of  FIG. 2 , but illustrating the socket without the presence of the ejector spring, and with a hexagonal lug nut received within the operating end of the socket; 
         FIG. 4  is a front elevational view of the prior art socket; 
         FIG. 5  is a vertical sectional view taken along line  5 - 5  of  FIG. 3 ; 
         FIG. 6  is a view similar to that of  FIG. 5 , but depicting the engagement between the socket and lug nut after initial rotation of the socket; 
         FIG. 7  is a perspective view similar to that of  FIG. 1 , illustrating the improved lug nut socket of the invention, and depicting the standard internal lug nut ejector spring within the socket; 
         FIG. 8  is a vertical sectional view similar to that of  FIG. 2 , but depicting the improved lug nut socket of the invention; 
         FIG. 9  is a view similar to that of  FIG. 3 , but illustrating the improved lug nut socket of the invention with the ejector spring removed and receiving a hexagonal lug nut; 
         FIG. 10  is a front elevational view similar to that of  FIG. 4 , but depicting the improved lug nut socket of the invention; 
         FIG. 11  is a vertical sectional view taken along the line  11 - 11  of  FIG. 9 , and illustrating the improved lug nut socket of the invention with a hexagonal lug nut seated within the socket; 
         FIG. 12  is a view similar to that of  FIG. 6 , but depicting the engagement between the improved lug nut socket of the invention and the lug nut after initial rotation of the socket; 
         FIG. 13  is a fragmentary perspective view illustrating positioning of an impact wrench equipped with the improved lug nut socket of the invention, prior to placement over an installed lug nut; and 
         FIG. 14  is a greatly enlarged, schematic view similar to that of  FIG. 11 , and including the most preferred dimensions of the improved lug nut socket of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The Prior Art Wheel Lug Nut Socket 
     Turning to  FIGS. 1-6 , a conventional wheel lug nut socket  20  is illustrated. The socket  20  includes an elongated, tubular metallic body  22  presenting an enlarged, open, operating end  24  and an opposed tool connection end  26 , with a tubular section  28  between the ends  24 ,  26 . 
     The tool connection end  26  includes a substantially square opening  30  designed to receive the square coupler  32  of a standard pneumatic lug socket wrench  34 , as illustrated in  FIG. 13 . The operating end  24  includes a radially enlarged, lug nut-receiving segment  36  having an internal operating surface  38 . The surface  38  (see  FIG. 5 ) presents six identical, circumferentially arranged concave surfaces  40 , with an apex surface  42  between each adjacent pair of concave surfaces. 
     The tubular section  28  is designed to receive a compressible coil lug nut ejector spring  44 ; the inner end  46  of spring  44  is received within an opening  48  through the sidewall of section  28 , in order to retain the spring  44  within the socket  20 . 
     As illustrated in FIGS.  3  and  5 - 6 , the segment  36  and operating surface  38  are configured and dimensioned to receive a conventional hexagonal wheel lug nut  50  within the segment  36 , such that the inner operating surface  38  engages the nut  50 . As depicted, the lug nut  50  has an outer surface  52  including six circumferentially arranged wrench flat surfaces  54  with a substantially pointed apex  56  between each adjacent pair of the flats  54 . Specifically, it will be observed that the inner operating surface  38  is designed so that portions of the outer nut surface  52 , namely the apices  56 , initially engage corresponding portions of the operating surface  38 , namely the concave surfaces  40 , when the socket  20  is installed on a nut  50 . 
     When a rotating socket  20  is installed as illustrated in  FIG. 5  on a nut  50 , the nut  50  is correspondingly rotated for removal from or attachment to a threaded wheel stud  58  secured to a drum (not shown). This socket rotation may be clockwise or counterclockwise for nut attachment or removal, as depicted by the directional arrows in  FIG. 5 . The socket  20  is conventionally mounted on a high-speed pneumatic wrench  34  ( FIG. 13 ).  FIG. 6  illustrates this operation during clockwise rotation of socket  20 , where it will be seen that the apex surfaces  42  come into contact with the nut flats  54  to rotate the nut  50 . It will further be seen that the nut apices  56  remain in contact with the concave surfaces  40  during socket rotation. The distance between the radial lines  60  in  FIG. 6  illustrates the arc through which the socket  20  must travel between the initial installation position of  FIG. 5  and the socket operating position of  FIG. 6 . Of course, the operation of socket  20  is identical when rotating in a counterclockwise direction. 
     As explained previously, the design of the conventional socket  20  unacceptably slows the removal and attachment of lug nuts onto the wheel studs  58 . This is because time is required for the rotating socket to properly seat and assume its drive position over each of the lug nuts before the nut may be removed. Given that in a racing pit stop a total of twenty nuts  50  need to be removed, and 20 new nuts  50  need to be installed, it will be appreciated that these time-wasting socket installation deficiencies inherent in the design of the standard socket  20  represent a significant time loss to the pit crew. 
     The Wheel Lug Nut Socket of the Invention 
     The improved wheel lug nut socket  62  is illustrated in  FIGS. 7-14 , and broadly includes a substantially tubular, open-ended metallic body  64  presenting an enlarged, open operating end  66 , an opposed tool connection end  68 , with a tapered tubular section  70  between the ends  66 ,  68 . 
     The tool connection end  68  includes a substantially square opening  72  designed to receive a square coupler  32  of a standard lug socket wrench  34 , illustrated in  FIG. 13 . The operating end  66  includes a radially enlarged, lug nut-receiving segment  76  having an internal operating surface  78 . The surface  78  (see  FIG. 11 ) presents six identical, circumferentially arranged concave surfaces  80  with substantially flattened apex surfaces  82  between each adjacent pair of concave surfaces. The tubular section  70  is designed to receive a compressible coil lug nut ejector spring  84 ; inner end  86  of the spring  84  is received within the opening  88  through the sidewall of section  70 , in order to retain the spring  84  within the socket  62 . 
     As illustrated in FIGS.  9  and  11 - 12 , the segment  76  and operating surface  78  are configured and dimensioned to receive a conventional hexagonal wheel lug nut  50 , previously described. However, and significantly different than the conventional socket  20 , the operating surface  78  of socket  62  is configured and dimensioned so that the nut  50  may be fully received within the section  78  with full clearance between the operating surface  78  and the lug nut outer surface  52 , i.e., so that the inner operating surface  78  may be located out of contact with the lug nut outer surface  52 . It will be appreciated that, owing to the speed of rotation of the socket  62  during placement thereof over a lug nut  50 , there may be contact between the surfaces  78  and  52  from the outset; nonetheless, the increased clearance provided between these surfaces facilitates rapid placement of the socket and consequent lug nut rotation. 
     When the socket  62  is installed on a nut  50 , as illustrated in  FIG. 11 , the socket  62  is rotated so as to correspondingly rotate the nut  50  for removal from or attachment to a threaded wheel stud  58 , as illustrated by the directional arrows in  FIG. 5 .  FIG. 6  depicts rotation of the socket  62  in a clockwise direction, where it will be seen that the flattened apices  82  come into contact with adjacent nut flats  54 , while the nut apices  56  are maintained in spaced relationship to the concave surfaces  80 . The distance between the radial lines  90  in  FIG. 6  illustrates the arc through which the socket  62  must travel between the full clearance position of  FIG. 5  and the socket operating position of  FIG. 6 . Again, counterclockwise rotation of socket  62  is identical in operation. 
     Attention is next directed to  FIG. 14 , which is a greatly enlarged schematic version of  FIG. 11 . As illustrated therein, the centers of opposed concave surfaces  80  are spaced apart a distance D, and the opposed apex surfaces  82  are spaced apart a distance D′. Correspondingly, the opposed nut apices  56  are spaced apart a distance d, and the opposed flat surfaces  54  of the nut  50  are spaced apart a distance d′. In accordance with preferred embodiments of the invention, the distance D is greater than the distance d; the distance D is preferably at least about 0.1 inches longer than the distance d, and more preferably from about 0.12-0.15 inches longer. Similarly, the distance D′ is greater than the distance d′; preferably, the distance D′ is at least about 0.04 inches longer greater than the distance d′, more preferably from about 0.04-0.07 inches longer. As further depicted in  FIG. 14 , the flattened surfaces  82  should have a width of at least about 0.02 inches, more preferably from about 0.03 inches. Moreover, the distance between each adjacent pair of flattened surfaces  82  should be at least about 0.4 inches, more preferably from about 0.45-0.5 inches. Finally, it will be observed that each concave surface  80  has a large radius central portion  92  with smaller radius end sections  94  leading to the adjacent surfaces  82 . 
     The configuration of the operating surface  78  relative to the nut  50  permits very rapid installation of the rotating socket  62  over a nut  50 . That is to say, owing to the full clearance between the socket operating surface  78  and the nut outer surface  52 , the pit crew members can more quickly make a complete wheel changeover. 
     The overall operation of lug nut removal or attachment using socket  62  is the same as with socket  20 , i.e., the socket  62  is coupled with the wrench  34 , and the wrench is operated to rapidly rotate the socket. The socket is then successively placed over the wheel lug nuts  50  for removal from or attachment thereof to the studs  58 . In the case of nut removal, once the wrench  34  is removed from the studs  58 , the ejector spring  84  serves to eject the removed nut  50  from the socket, so that the next nut may be removed. When a fresh wheel and tire are mounted onto a race car drum, the crew member places the socket over a pre-adhered nut  50  on the wheel, so as to compress the spring  84  and allow attachment of the nut. The significant difference in the operation of socket  62 , as compared with that of the socket  20 , chiefly resides in the ability to more rapidly and easily install the socket  62  over nuts  50 . 
     Actual experience with the sockets  62  as compared with the conventional sockets  20  has demonstrated that pit times involving complete replacement of a race car&#39;s wheels and tires are substantially reduced, even for inexperienced pit crews. Indeed, sub-par crews performing a pit service using standard sockets  20  will commonly clock a pit time exceeding 15 seconds. However, these pit times can regularly be reduced by such crews to the 12-13 second time range using the improved sockets  62 . 
     In greater detail, it has been found that the improved sockets of the invention will engage and “grab” a lug nut within 1-2 revolutions of the socket, and less hand pressure on the wrench is required. This decreases the tire change time by about 0.4 seconds per side, or almost one second per pit stop. A one-second advantage translates to approximately 275 feet at 180 mph on the track, meaning that a fast pit stop can put a racer ahead of the field. Given that a typical NASCAR CUP race will involve 15-20 pit stops, this advantage is quite considerable over the entire course of a race. 
     The tapered design of the socket of the invention permits the larger inside dimensions of the socket operating end, and also makes the socket smoother to handle by crew members. The lack of any peripheral lip adjacent the operating end of the socket also eliminates the problem of “grabbing” adjacent nuts during removal. 
     All of these factors contribute to the improved performance of the present sockets versus those of the prior art. Most important, the sockets hereof can turn a mediocre tire-change crew member into a superior member, while reducing pit times.