Abstract:
A pliers has specifically configured elongate jaws of about rectilinear construction with multiple position adjustability to variously operatively engage a plurality of slack adjustment services of diverse commercial air brakes to check the slack.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to tools for checking the slack on an automotive air brake. This invention more particularly relates to tools for checking the slack in air brake automotive slack adjusters. 
   2. Discussion of the Background and Prior Art 
   A typical foundation air brake used on each wheel, or wheel-pair, of large vehicles such as trucks and buses includes an air chamber rigidly mounted on a non-rotating portion of an axle structure near one of the wheels. A piston within the chamber is moved in one direction by compressed air controlled by a valve operated by the driver of the vehicle to apply the brakes by means of a push rod attached to the piston and connected by a clevis to a lever, called a slack adjuster, mounted on one end of a cam shaft. This movement of the lever transmits torque through the camshaft to rotate an S-shaped cam, or S-cam, rigidly mounted on the other end of the shaft. The S-cam transmits the force through cam-follower rollers supported at the ends of brake shoes to force the brake shoes apart and the brake pads mounted on them against the brake drum to brake the vehicle. 
   The brake shoes are set to move a certain minimum distance before the pads touch the drums, and this distance constitutes slack in the movement of the slack adjuster lever. As the brake drum and the pads wear, the lever has to move farther to apply the brakes, which increases the range of slack movement. This freedom of motion must be limited so that it does not exceed a certain maximum amount, and for that reason the lever includes means for adjusting its angular setting on the camshaft relative to the orientation of the S-cam. The slack adjuster is not directly affixed to the camshaft but is rotatably mounted on a worm gear that has internal spines mounted on spines on the end of the camshaft to prevent the gear from rotating relative to the shaft. The lever can rotate on the worm gear only to a limited extent within a range determined by the engagement of gear teeth on the outer surface of the gear with a worm mounted in a fixed location within the slack adjuster lever. The worm is rotatable about its own axis, which is perpendicular to the axis of the cam shaft, and it has a polygonal head, which is usually hexagonal but is square on some slack adjusters, and is somewhat accessible from outside the slack adjuster to permit the worm to be rotated on its axis by a socket wrench. Excess slack is taken up by rotating the head to adjust the angle of the lever to the proper position to cause the S-cam to begin to apply pressure to the roller followers after the outer end of the push rod extending from the air chamber has moved only a short distance, typically between ½″ and ¾″ from the position it occupies when the piston is not under pressure from compressed air. 
   Other slack adjusters are referred to as self-adjusting or automatic because they have sensors that detect the amount of slack and are connected to actuating means in the slack adjusting lever to rotate the worm to take up excess slack. However, even the automatic slack adjusters have provision for some manual check. 
   The slack in each brake of a vehicle so equipped needs to be checked regularly to be sure that the brake shoes apply balanced pressure on the drums so that they can bring the vehicle to a halt without causing it to swerve or skid as it stops. In organizations that operate fleets of vehicles having air brakes, mechanics are required to inspect the brakes on a regular schedule, but in addition, the drivers are also supposed to check the slack adjusters at the beginning of each day&#39;s trip. 
   Recent state and federal regulations, such as the Department of Transportation&#39;s 1198 edict, mandate that all truck drivers must be able to measure the slack in the air brakes of the vehicles they own, operate or drive. Thus the air brakes must be checked daily, and certainly before each trip, to determine if the slack of each air brake assembly is within or exceeds the safe working maximum limits. 
   In the field relating to air brake slack check tools, it is generally known to provide a tool having fixedly spaced engagement members, which members are positioned for engagement of different but a limited number of slack check surfaces. One such tool is disclosure is U.S. Des. 296,750, granted Jul. 19, 1988 to Hamatani (the “Hamatani tool”). The Hamatani tool required two hands to be operable, one hand engages the handle and the other hand adjusts and sets the position using a wing nut. The Hamatani tool relies on the wing nut to hold the set position when the tool was in use. A present widely used tool, quite similar to the Hamatani tool construction, is the Brake Slack Check OTC 5052 tool, commercially available from OTC a division of SPX Corporation, Owatonna, Minn. (the “OTC tool”). The OTC tool provides a four position construction. The OTC tool, like the Hamatani tool, requires two hands to be operable, and provides a limited range of operable positions. The OTC tool also generally requires a two-person operation; a first person operates the tool while a second person in the cab applies force to the brake to permit the first person to use the tool to check the clearance or slack. 
   The air brake slack check the art desires a tool, which readily provides sufficient gripping and leverage forces for a broad range of slack adjuster surfaces of diverse models of trucks and buses, and yet is practical in design and construction. The air brake slack check art further desires a tool, as aforesaid, which eliminates the number of hands and operators, and yet provides the necessary slack check leverage. The present invention provides a solution to the foregoing slack check art requirements and needs. 
   In the field related to pliers, it is generally known to provide pliers that are adjustable. Adjustable pliers are disclosed in U.S. Pat. No. 6,892,609, granted May 17, 2005 to Kuo, U.S. Pat. No. 4,603,607 granted Aug. 5, 1986 to Schaffner et al, U.S. Pat. No. 5,134,908, granted Aug. 4, 1992 to Fisher, and U.S. Pat. No. 4,890,519 granted Jul. 2, 1990 to Le Duc. 
   SUMMARY OF THE PRESENT INVENTION 
   The automotive air brake slack check tool includes first and second members having respective handles and respective elongate jaws integral with the respective handles, and means for adjustably pivotably connecting the first and second members so that the jaws are adjustably disposed in a plurality of operable positions, so that the jaws grippingly engage differently sized oppositely disposed air brake slack adjustor check surfaces, with a sufficient gripping force and leverage exerted in each position so that a one-person slack check is effected in each position, without the need for a second person in the cab to actuate the brake. The slack check tool is adjustable from a fully closed position to 7 operable positions. Each jaw has respective teeth, with the respective teeth in facing parallel disposition in each operable position, and the respective teeth being in angular disposition in the fully closed position. The elongated jaws, in each respective position, permit the slack adjustor check surfaces to be moved at least about up to 1 inch without the need for brake actuation. That is, one person checks the air brake slack without the need for a second person to actuate the brake. 
   Each elongate jaw has a rectangular sectional configuration and a width to height ratio of about 2:1. This construction was found to be operable for a broad range of slack adjustor check surfaces, and exert the necessary leverage to move the air brake adjustor the requiste slack check distance, without flexure of the jaws. 

   
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
       FIG. 1  is a front elevational view of the tool of the present invention; 
       FIG. 2  is a right rule elevational view of the tool of  FIG.1 ; 
       FIG. 3  is a rear elevational view of the tool of  FIG. 1 ; 
       FIG. 4  is a greatly enlarged partial view of the distal end of the tool as shown in  FIG. 3 ; 
       FIG. 5  is a front elevational view of one member of the tool of  FIG. 1 ; 
       FIG. 6  is a rear elevational view of the opposed member of the tool of  FIG. 1 ; 
       FIG. 7  is a front view of the tool of  FIG. 1  in an adjusted operational position; 
       FIG. 8  is a left side elevational view of tool of  FIG. 1 ; 
       FIG. 9  is a greatly enlarged sectional view taken along line  9 - 9  of  FIG. 5 ; and 
       FIG. 10  is a greatly enlarged sectional view taken along line  10 - 10  of  FIG. 6 . 
   

   DESCRIPTION OF THE INVENTION 
   Referring to the FIGS., there is shown air brake slack check tool of the present invention  10 . Tool  10  includes two members  11  and  12 . Members  11  and  12  are pivotably connected by adjustable pivot assembly  13 . Adjustable pivot assembly  13  includes pivot pin  14 , elongate or race slot  15  that slidably rotatably receives pin  14 , and an arcuate ridge or element  16 . Member  11  is formed with jaw  25 , and member  12  is formed with jaw  55 . Arcuate ridge 16  slidably operably engages each respective arcuate slot or groove  53  so as to provide 7 operable positions. Pivot pin  14  is rotatably disposed in through hole  21 . 
   Adjustable pivot pliers construction are in well known in the pliers art, as shown and described in U.S. in the field related to pliers, it is generally known to provide pliers that are adjustable. Adjustable pliers are disclosed in U.S. Pat. No. 6,892,609, granted May 17, 2005 to Kuo, U.S. Pat. No. 4,603,607 granted Aug. 5, 1986 to Schaffner et al, U.S. Pat. No. 5,134,908, granted Aug. 4, 1992 to Fisher, and U.S. Pat. No. 4,890,519 granted Jan. 2, 1990 to Le Duc, which disclosures are incorporated herein by reference thereto. One commercially available adjustable pliers is the 440 model by Channellock®, Meadville, Pa. 16335. 
   Referring specifically to  FIG. 6 , member  11  includes handle  18  having thermoplastic grip cover  19 , intermediate portion  20  with transverse through hole  21  for slidably receiving pivot pin  14 , and jaw  25 . Jaw  25  is formed with intermediate portion  20  having arcuate ridge element  16 . Jaw  25  is of elongate  27  are integral and contiguous with intermediate portion  20 . Distal end  26  includes a distal planar end surface  28  and angularly disposed contiguous planar surface  29 , and a rectilinear about planar, surface  50 , as best shown in  FIGS. 1 ,  6  and  10 . Jaw  25  includes about planar outer surface  50 , oppositely disposed planar sides  31  and  32  and inner side  33  having teeth  34 . The rectilinear sectional configuration of Jaw  25  has a width A and height B, wherein width A is substantially greater than the height B ( FIG. 10 ). The sectional width A is defined as the distance between planar sides  31  and  32 . The sectional height B is defined as the distance between outer surface  50  and the base  47  of teeth. 
   Referring to FIGS.  1 , 5  and  9 , member  12  is of one-piece integral hardened 1080 steel construction. Member  12  includes handle  48  having thermoplastic grip cover  49 , and intermediate portion  51  formed with slot or race  15  for slidably and rotatably receiving pin  14 . A plurality of arcuate grooves e.g.  53  are formed-intermediate portion  51 . Each groove is sized to removably slidably receive arcuate ridge or element  16 . Member  12  includes jaw  55 . Jaw  55 , like jaw  25 , has a rectilinear sectional configuration wherein the corresponding width A to height is about 2:1. Referring specifically to  FIG. 9 , there is shown the cross section of jaw  55 . Jaw  55  includes outer planar surface  60 , opposed planar surfaces  61  and  62 , teeth  64  and teeth base  63 . The width A to height B ratio is likewise about 2:1. this manner of construction, the user selectively positions in ridge or element  16  in a respective groove so position as to provide an adjusted position for the jaws  25  and  55  to provide gripping engage a corresponding specifically size air brake slack adjuster, and exert the requisite force with that flexure of the jaws. 
   Referring specifically to  FIGS. 3 and 4 , the air brake slack check tool  10  is shown in the fully closed position. In this position the respective distal ends  28  and  58  of jaws  25  and  55  are in contacting engagement at contact point  86 , and respective inner planar surfaces  68  and  78  substend on acute angle C. 
   Referring specifically to  FIG. 7 , there is shown air brake slack check tool  10  in operable engagement with air brake slack adjuster  70 . Jaws  25  and  55  are in parallel disposition and the respective teeth are grippingly engaged with oppositely disposed planar surfaces  71  and  72  of slack adjuster  70 . In this manner of construction, the user in gripping handles  18  and  48  is able to exert a sufficient force to move adjuster  70  up to about 1 inch and thereby check the slack without the need for an operator in the cab to press the brake pedal. The specifically configured jaws  25  and  55  fully engage surfaces  71  and  72  during the slack check without flexure of the jaws. 
   It has been found that by providing a jaw of hardened steel wherein the width A is substantially greater than height B, and specifically in 2:1 ratio a substantial force may be exerted without flexure of the jaw as required by ASME B107.23 standard. It is noted that prior art heavy duty prior pliers were directed to at least one of-the jaws having a concave beefed-up, outwardly extending position. The present pliers eliminates that construction. 
   The tool of the present invention is useful for a broad range of U.S. and foreign made trucks and buses, including without limitation, Mack®, Freightliner®, and Kensworth®. The tool of the present invention is operable with a broad range of S-cam slack adjustors. 
   The invention has been described with reference to specific embodiments and materials and components, but it will be obvious to those skilled in the air brake slack check art that the embodiments, materials, and components may be modified without departing from the true scope of this invention.