Patent Abstract:
A support arrangement, operable to clamp a cam tube for a drum brake assembly in position relative to an adjacent vehicle component, includes a first jaw having a first pair of arms, each of which has an one opening in an inclined end section, a second jaw having a second pair of arms, each of which has an opening in an inclined end section, and a base associated with the vehicle component and having a third pair of arms. Each of the third pair of arms also has an opening in its end section. Bolts or other such fastener elements are receivable within aligned sets of openings in the first, second, and third pairs of arms, permitting displacement of the first and second jaws relative to the base upon adjustment of the fasteners so that the jaws grip the tube and clamp the tube in its proper position. A clamping process is also described.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention provides a cam tube support for a drum brake assembly that can adjust to an outer cam tube diameter so that good contact is always provided between the support and the cam tube. 
     2. Description of Related Art 
     Various drum brake cam tube support arrangements are in use today. However, with typical arrangements, it is often difficult to maintain consistent contact with cam tubes when using supports designed to accommodate variations in drum brake cam tube locations. Conversely, supports that maintain consistent contact with cam tubes typically fail to permit variations in support locations. 
     U.S. Pat. No. 3,076,531 to Hanley et al. shows a single tubular brake support that is adjustably secured within a brake spider. The mounting is rotatable around splines of the brake spider. 
     U.S. Pat. No. 5,174,680 to Nakamura et al. discloses a pair of rings brought together by bolts so as to ramp together between a shaft and a wheel and provide torque transfer. Guide portions on the shaft are unnecessary, but the ramp action is strictly limited by the sizes of the shaft and the hole in the wheel. 
     U.S. Pat. No. 5,649,685 to Keller shows a muffler support apparatus including two members that surround a muffler tube and are clamped together. The muffler support apparatus surrounds the tube and bolts vertically. 
     U.S. Pat. No. 6,240,806 to Morris et al. shows a non-welded cam tube support assembly. The tube includes a support plate that resists torsional loading and provides for either inboard or outboard mountings. An inner hole of the plate is irregularly shaped to tightly engage the cam tube. 
     U.S. Pat. No. 7,537,224 to Morris et al. shows a cam shaft support enclosure that has a two-piece, non-welded assembly. Two brackets mate with each other by sliding over a cam tube such that movement of the cam tube is minimized. Contact with the cam tube is maintained by tabs around an opening of the assembly. The overall fastener is movable along the length of the cam tube. 
     U.S. Patent Application Publication 2006/0021834 to Kwasniewski shows a cam washer that cooperates with a cam tube seal lug to reduce vibration, prevent corrosion, and hold a seal in place. 
     SUMMARY OF THE INVENTION 
     Introduction of wide-based tires has resulted in increased vibration and subsequent damage to drum brake cam tube assemblies. The present invention is intended to support drum brake cam tubes in such a way as to reduce vibration that can result in this sort of damage to the cam tube assemblies, and provides an improvement over an existing part that was first designed over 30 years ago. A support according to this invention can be attached to a welded or bolted frame member, may be used either in production or as a retrofit in the field, and can be installed independent of the cam tube assembly process. The present cam tube support serves to withstand the cantilevered load of an air chamber tube assembly while accommodating a variety of tube diameters via support jaw camming. Separate tube support pieces that do not rely on splines for changing the orientation around the cam tube are used, and form a three-piece assembly that move together to improve holding of cam tubes having different diameters at different locations along those cam tubes. 
     According to one embodiment of the invention, a support arrangement operable to clamp a tube for a brake assembly in position relative to an adjacent vehicle component includes a first jaw having a first pair of arms, each of which has an one opening in an inclined end section, a second jaw having a second pair of arms, each of which has an opening in an inclined end section, and a base associated with the vehicle component and having a third pair of arms. Each of the third pair of arms also has an opening in its end section. Bolts or other such fastener elements are receivable within aligned sets of openings in the first, second, and third pairs of arms, permitting displacement of the first and second jaws relative to the base upon adjustment of the fasteners so that the jaws grip the tube and clamp the tube in its proper position. A clamping process is also described. 
     In certain embodiments of the invention, the jaws have respective solid central recurved portions interconnecting the arms of the jaws and forming part-elliptical or part-circular recesses between the jaw arms. The inclined end sections of the jaws are bent relative to these central portions to provide the jaws with a camming action as the fasteners are tightened. The openings in the jaws and the base are preferably configured as oblong slots, and, when the arrangement is assembled, the oblong jaw slots have longer dimensions extending in directions that are not the same as directions in which longer dimensions of the oblong base slots extend. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a cam tube support fully clamping a partially illustrated cam tube in position relative to an associated vehicle component. 
         FIG. 2  is a front exploded view of certain components of the support shown in  FIG. 1 . 
         FIG. 3  is a side view of the components shown in  FIG. 2 . 
         FIG. 4  is a more comprehensive, perspective view of the cam tube and certain associated parts. 
         FIG. 5  is a side view of the structure shown in  FIG. 4 . 
         FIG. 6  is a perspective view similar to  FIG. 4 , but showing certain components of the cam tube support in alternative positions. 
         FIG. 7  is an enlarged plan view of the base of a cam tube support according to the invention. 
         FIG. 8  is an enlarged plan view of a jaw of the cam tube support according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The side view provided by  FIG. 1  shows a partially illustrated cam tube  10  as fully clamped in position relative to an axle tube or other such unsprung vehicle component  12 , such as a suspension arm or other linkage, by a clamping cam tube support  14 . In one preferred configuration of the invention, when the cam tube  10  is mounted in position in a car, truck, or other such vehicle, a rotatable cam shaft (not shown) extends through the cam tube  10  to interconnect a fluid brake actuator and slack adjuster arrangement with a drum brake cam, which is operable to expand drum brake shoes apart in a known manner. Such cam shafts are disclosed, for example, in the Hanley et al. (&#39;531), Morris et al. (&#39;806), and Morris et al. (&#39;224) patents mentioned above as well as the Kwasniewski (&#39;834) publication mentioned above. The entire disclosure of each of the Hanley et al. (&#39;531), Morris et al. (&#39;806), and Morris et al. (&#39;224) patents mentioned above, and the entire disclosure of the Kwasniewski (&#39;834) publication mentioned above, are incorporated herein by reference as non-essential subject matter. 
     The clamping cam tube support  14  is composed of three primary parts, including a base  16  secured by welds  18  or in any other suitable manner to the unsprung vehicle component  12 , an approximately U-shaped lower jaw  20 , and an approximately U-shaped upper jaw  22 . As illustrated in the exploded plan view of  FIG. 2 , the base  16  has an approximately Y-shaped configuration, but the base  16  could take other forms, and could be U-shaped as well. When the clamping cam tube support  14  is in use, a pair of threaded bolts  24  may pass through aligned slots in the legs of the base  16  and the jaws  20  and  22 . Cooperating nuts  26  may be tightened onto the ends of the bolts  24  to secure the base  16  and jaws  20  and  22  together, thereby fastening the cam tube  10  to the vehicle component  12 . 
       FIG. 2  provides an illustration of the base  16  and the jaws  20  and  22  in an exploded plan view. The base  16  is shown as having a central section  29  with a mounting surface  30 , adapted to be secured on a corresponding surface of the component  12  by the welds  18 . The base  16 , of course, could be attached to the component  12  in another suitable way or integrally formed with that component. The base  16  also has a pair of upstanding extensions defining arms  32 . Each arm is provided with an oblong slot opening  34 , with the longer dimension of the opening oriented roughly vertically. The term “vertically” is used here and elsewhere in this specification in a non-limiting manner, and, here, refers to a direction in which the arms  32  extend away from the central section  29 . A recess  36  defined between the arms  32  of the base has a circumferential wall  38  with a contour matching the contour of the outer surface of the cam tube  10 . 
     The lower jaw  20  is shown in  FIG. 2  as having a solid central recurved portion  40  and a pair of arms  42 . Each arm  42 , near its end  43  distal the central portion  40 , has an oblong slot opening  44 , with the longer dimension of the opening oriented roughly horizontally. The term “horizontally” is used here and elsewhere in this specification in a non-limiting manner, and, here, refers to a direction approximately perpendicular to the direction in which the arms  42  extend away from the central portion  40 . 
     The upper jaw  22  has a configuration that is similar to that of the lower jaw  20 , and has a solid central recurved portion  46  and a pair of arms  48 . Each arm  48 , near its end  49  distal the central portion  46 , has an oblong slot opening  50 , with the longer dimension of the opening oriented roughly horizontally, similarly to slot openings  44 . When the clamping cam tube support  14  is in use, the jaws  20  and  22  are oriented such that each arm end  43  is adjacent a corresponding arm end  49 , and the central portions  40  and  46  are located away from each other. A recess  52  defined between the lower jaw arms  42  is surrounded by a circumferential wall with a contour matching the contour of the outer surface of the cam tube  10 , while a recess  54  defined between the upper jaw arms  48 , similarly, is surrounded by a circumferential wall with a contour matching the contour of the cam tube outer surface. 
     The base  16  and the jaws  20  and  22  are shown in  FIG. 3  in an exploded side view. It is apparent from  FIG. 3  that each lower jaw arm  42  has an inclined or canted section  45  adjacent its end  43 , and that each of the openings  44  is disposed in one of the inclined or canted sections. Each upper jaw arm  48 , similarly, has an inclined or canted section  47  adjacent its end  49 , with each of the openings  50  disposed in one of the inclined or canted sections  47 . The sections  45  and  47 , as shown, are inclined at approximately 15-20 degrees relative to the remainder of the respective jaw arm, but the amount of inclination shown is not to be considered limiting in any way. Although “camming” would be produced at any inclination angle in the 1-89 degree range, the range of preferred inclination angles is important due to load. Increasing the sizes of the openings  34 ,  44 , and  50  would allow a wider range of angles. 
     The amount of inclination provided to sections  47  can be varied as required to provide more, or less, clamping force to the barrel of the cam tube  10 . In conjunction, as the angle of inclination increases, so must the size of the openings  44  and  50  be varied to accommodate insertion of the bolts  24  when the jaws are in a vertical position while remaining small enough to prevent the head of the bolt  24  and the nut  26  from passing through the openings when tightened. The clearance of the jaws  20  and  22  relative to the tube  10  will determine the travel of the jaws to the clamping position and, in combination with the angle of inclination, will determine the amount of clamp force that is developed. 
     When different cam brackets are installed, they will always be in slightly different locations because of common variations in the manufacturing process. The two-direction slots allow the clamping tube support to function even with this variation in tube locations. The horizontal slots in jaws  20  and  22  accommodate variation in the horizontal direction, while the vertical slots in the base  16  accommodate variation in the vertical direction. When assembly of the three parts comes together with bolts, the sets of slots allow the support to always “center-up” on the cam tube and achieve a good clamp. The support can also be disassembled and re-used as many times as necessary, avoiding the need to cut known support arrangements off the axle and the associated need for re-welding when a new cam bracket is installed. 
       FIG. 4  is a more comprehensive view of the cam tube  10  and certain parts associated therewith.  FIG. 4  shows the tube  10  in a clamped condition, after the support  14  has been securely clamped onto the outer surface of the cam tube in a manner to be described. It is to be understood that the base  16  must be welded to the relevant vehicle component  12  (not shown in  FIG. 4 ) before clamping can take place. The cam tube  10  shown in  FIG. 4  extends from a bracket  56 , securable to an axle housing or other unsprung vehicle structure by bolts receivable in holes  60 , to an attachment flange  58 , securable to a drum brake spider, backing plate, or other such element. The rotatable cam shaft (not shown) protrudes in a conventional manner through the cam tube end opening  62  and positions the drum brake cam thereon between drum brake shoe ends for brake actuation.  FIG. 4  also illustrates a fitting  64  by which grease or another lubricant may be supplied to the interior of the cam tube  10  to lubricate cam shaft bushings provided for the cam tube. 
     The clamping tube support  14  may be used in several ways to secure the tube  10  in position relative to the component  12 . One such way is now described with reference to  FIGS. 1-3 , and  5 . The pair of slot openings  44  in the lower jaw arms  42  and the pair of slot openings  50  in the upper jaw arms  48  are aligned, and the shafts of a pair of bolts  24  are passed through the aligned slot openings  44  and  50  in a direction indicated by an arrow  55  in  FIG. 3 . Ends of the bolt shafts are then passed through the slot openings  34  provided in the arms  32  of the base  16 , and the nuts  26  are threaded onto the ends of the bolt shafts and tightened to secure the base  16  and jaws  20  and  22  together. As the nuts are tightened, the head of each bolt  24  and a respective one of the nuts  26  are displaced toward one another. Due to the presence of the inclined jaw arm sections  45  and  47 , as the nuts  26  are tightened, the lower jaw  20  tends to pivot clockwise in the direction indicated by an arrow  66  in  FIGS. 1 and 5 , and the upper jaw  22  tends to pivot counterclockwise in the direction indicated by an arrow  68 . As the jaws  20  and  22  move in this way, edges of the circumferential walls surrounding the jaw recesses  52  and  54  frictionally engage or actually dig into the outer barrel surface of the cam tube  10 , thereby securing the tube  10  in position relative to the component  12 . The camming or lever action provided as the nuts  26  are tightened allows the jaws to self-center and tightly clamp onto the cam tube so that vibration, which could damage the cam tube assembly, is reduced. Although the two jaw parts try to separate, the slot openings are designed in such a way that jaw separation is limited, and the jaws bite down on the cam tube barrel as the parts get tighter. The present invention permits relative movement between the jaws and the cam tube along the length of the cam tube before clamping, and is constructed such that adequate contact is maintained with the cam tube by the camming action produced by the support base and jaw configurations after clamping occurs and the relative movement mentioned is prevented. 
     A comparison of  FIGS. 5 and 6  illustrates that the jaws  20  and  22  are securable to either side of the base  16 . The jaws  20  and  22  thus may be oriented so as to face in either cam tube axial direction, making attachment of the cam tube  10  to the component  12  exceptionally easy. 
       FIG. 7  is an enlarged plan view of the base  16  illustrating the arrangement of the oblong slot openings  34  in the base arms  32 , while  FIG. 8  is an enlarged plan view of either the lower jaw  20  or the upper jaw  22 , illustrating the arrangement of the oblong slot openings  44  or  50  in the arms  42  or  48 , respectively. It is evident that, to produce the jaws  20  and  22  most efficiently, they should have essentially the same configuration. By orienting the oblong slot openings  34  in the arms of the base  16  “vertically” and the slot openings  44  and  50  in the arms of the jaws  20  and  22  “horizontally,” appropriate positional adjustment of the jaws  20  and  22  with respect to both the cam tube  10  and the base  16  is facilitated. Orienting the slot openings  44  and  50  horizontally, as illustrated, serves to limit relative movement of the jaws to ensure tight and secure engagement of the of the circumferential walls surrounding the recesses  52  and  54  and the outer surface of the cam tube  10 . 
     It is conceivable to configure the invention such that it has a single piece jaw instead of two jaws. The U-shaped upper jaw  22 , for example, could alone be used to secure the tube  10  to the base  16  and provide clamping. 
     Although the use of steel as a jaw material is contemplated, the jaws  20  and  22  could be made of any of a variety of materials. The slot openings  34 ,  44 , and  50 , and the recesses  36 ,  52 , and  54 , could be formed by way of any of a variety of processes, such as stamping or cutting by water jet or laser, or a combination of such processes. Selection of the bend angle to get the best clamping action may be necessary, depending on the particular environment in which the invention is utilized. The “arch” that actually contacts the barrel could be an elliptical shape that contacts the barrel in the flatter section, or a simple part-circular shape that contacts the barrel mostly at the top when in position. Recesses shaped to accommodate other barrel shapes, such as barrels having square cross sections, are also contemplated. 
     By way of the present invention, a cam tube support, adjustable to accommodate various tube diameters, is provided. The slot configuration of the three-piece device allows jaw position adjustment both horizontally and vertically, permitting accommodation of variations in tube diameter and providing for various tube support locations. Pieces of the device are structured so that the support can face either axial direction of the tube, providing additional mounting configurations. As the three support pieces are fastened together in a simple manner with two bolts, no welding is necessary, and manufacturing can be simplified. The base  16  can be pre-welded and attached to the vehicle component  12  without the need to precisely locate the base  16  on the component  12 . By having the cam tube support pieces wedge or cam together when the mounting bolts are tightened, secure contact with the cam tube is provided, and vibrations are reduced. The present invention thus provides varied mountings utilizing a simple design, with three main pieces holding the relevant vehicle component and the cam tube in proper relative position. The invention allows for multi-axis variations in location, and consistent contact is maintained when a cam tube is installed. 
     The cam tube support adjusts to location and tube diameter in such a way that it always provides adequate contact between the support and the cam tube. Clamping is accomplished by having one or two clamping members provide adequate clearance for easy installation. As a final adjustment, the clamping members self-center and tightly clamp onto the cam tube because of the cam or lever action caused by the shapes of the clamping members. The invention can be installed on new equipment or retrofit in the field, is attachable to a welded or bolted support leg, and accommodates significant variation in tube diameter and location. 
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

Technology Classification (CPC): 8