Abstract:
A hydraulic brake control apparatus for attaching to an open ended handlebar of a vehicle, the handlebar having a longitudinal axis. A brake housing is attachable to the handlebar, the brake housing including a first section residing outside the handlebar and abutting the open end of the handlebar, and a second section sized and shaped to be received inside the handlebar. A master cylinder is disposed within the first section, the master cylinder having a bore with a bore axis that is oriented transverse to said axis of the handlebar and a master cylinder actuator is in operative association with the master cylinder. A micro-adjust mechanism, a macro-adjust mechanism, and a clamp mechanism is also provided.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to brake systems. More particularly, the invention relates to brake control devices, which are used with a brake for engaging a wheel of a vehicle. 
         [0002]    Many vehicles, such as bicycles, utilize a braking system that causes the application of pressure to a rotating wheel or a disc rotor mounted to a rotating wheel. Many of these braking systems utilize a mechanism with a hand lever to generate pressure with a hydraulic fluid. This pressure is transferred through a hydraulic line or conduit to a brake apparatus, which may include a caliper having brake pads, such that the hydraulic pressure is applied to the pads to squeeze the pads against the rotating part to impart a braking force thereto. The rotating part could be a wheel rim or a rotor, for example. 
         [0003]    Two general types of brake systems are commonly seen in the bicycle market and these use different mechanisms to convey braking force from a hand lever mounted to the outside of a handlebar down to the wheel to stop the bicycle. The first, and typically least expensive way, is the use of a steel cable positioned in a housing which is pulled by the hand lever. This cable is connected to a brake caliper near the rim of a wheel and when pulled, generates force between paired brake pads. The resulting friction slows the bicycle. The other way is the use of hydraulic fluid in a hydraulic line to convey the hand-generated force down to the brake caliper. This hydraulic fluid is pushed by a master piston by operating a hand lever and pushes against a slave piston at or near the caliper, which causes the brake pads to move against the rim and slow the bicycle. Cable actuated brake systems may use different lever distances to increase the hand force and generate a higher brake force between the brake pads and rim, in contrast to hydraulic brakes which use different piston diameters to increase the hand force. 
         [0004]    An advantage of hydraulic actuated brakes is the lower energy loss in the hydraulic line in contrast to the steel cable, especially when the steel cable is fished through the interior of the bicycle handlebar and frame member(s), because of the amount of friction created between the cable and the housing. This makes hydraulic brake systems an attractive option for road and triathlon bicycles. Triathlon and time trial style bicycles are designed to be very aerodynamic and the brake lines are typically hidden inside the handlebar and the frame to reduce drag. The triathlon and time trial style handlebar has a special shape to allow the rider to ride the bike in an aerodynamic position. For this reason, effective hydraulic brake systems are particularly advantageous when applied to triathlon and time trial bicycles. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    In light of the present need for an improved hydraulic brake control apparatus and in particular an apparatus that is provided in an overall ergonomic package, a brief summary of various exemplary embodiments is presented. Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various exemplary embodiments, but not to limit the scope of the invention. Detailed descriptions of an exemplary embodiment adequate to allow those of ordinary skill in the art to make and use the inventive concepts will follow in later sections, but it should be understood that minor variations of these concepts are contemplated by the invention. 
         [0006]    Some aspects of the invention include a hydraulic brake control apparatus designed to work with a rim brake caliper and has a housing section that may be mounted at the forward/leading end of a triathlon style handlebar, preferably in an abutting fashion i.e. in contact with the end of the handlebar, and a section that clamps in the interior on an inner surface of the handlebar and also may locate the hydraulic line outlet portion inside the handlebar. The hydraulic system may be closed and may omit compensating structure to address expansion of hydraulic fluid due to heat because a rim brake caliper does not heat brake fluid during braking (in contrast to a disc brake caliper). This closed system allows having both the quick release and the pad contact adjustment at the brake housing, which is convenient and comfortable to use, including during riding. A radial master cylinder may help to make the brake lever and apparatus very compact and aerodynamic and a symmetric working clamp mechanism driven by an offset screw leaves sufficient room in the middle of the housing to locate the hydraulic line port inside the handlebar. The brake control apparatus may easily be mounted to a handlebar and only one screw needs to be tightened. 
         [0007]    One aspect of the invention is a hydraulic brake control apparatus for attaching to an open-ended handlebar of a vehicle, the handlebar having a longitudinal axis. The apparatus includes a brake housing attachable to the handlebar. The brake housing includes a first section residing outside the handlebar and abutting the open end of the handlebar, and a second section sized and shaped to be received inside the handlebar. A master cylinder is disposed within the first section, the master cylinder having a master cylinder chamber with a chamber axis that is oriented transverse to the axis of the handlebar. A master cylinder actuator is provided in operative association with the master cylinder. 
         [0008]    Another aspect of the invention is a hydraulic brake control apparatus for controlling the braking of a vehicle, the vehicle having a handlebar with a handlebar axis including a brake housing attachable to the handlebar. A master cylinder is disposed in the brake housing having a bore axis oriented transverse to the axis of the handlebar. A master cylinder actuator is pivotally attached to the housing and in operative association with the master cylinder. An adjustment cylinder is disposed in the brake housing in communication with the master cylinder, the adjustment cylinder including an adjustment cylinder chamber provided with a volume of fluid and one or both of a micro-adjust mechanism and a macro-adjust mechanism is provided that is operable upon the adjustment cylinder to change the fluid volume of the adjustment cylinder chamber. 
         [0009]    Another aspect of the invention provides a clamp mechanism for attaching a brake control apparatus to an open ended handlebar of a vehicle, the handlebar having an inside surface and a longitudinal axis, including a brake housing attachable to the handlebar, the brake housing including a first section residing outside the handlebar and a second section sized and shaped to be received inside the open end of the handlebar, the clamp mechanism arranged symmetrically about the second section of the brake housing to space apart the second section from the handlebar and operating to secure the brake housing to the inside surface of the handlebar by expanding radially, the clamp mechanism including an adjustor, the adjustor accessible from the first section and extending through the first and second sections and being offset from said axis of the handlebar. 
         [0010]    These and other features and advantages of the present invention will be more fully understood from the following description of one or more embodiments of the invention, taken together with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0011]      FIG. 1  is a cross-sectional view of a brake control apparatus according to one embodiment of the invention; 
           [0012]      FIG. 2A  is a cross-sectional side view of the housing portion of the brake control apparatus of  FIG. 1 ; 
           [0013]      FIG. 2B  is a perspective front view of the housing of  FIG. 2A ; 
           [0014]      FIG. 3  is a perspective rear view of the brake control apparatus of  FIG. 1 ; 
           [0015]      FIG. 4  is a perspective top view with a cross-sectional view through the axis A shown in  FIG. 1 ; 
           [0016]      FIG. 5  is a front view of the brake control apparatus of  FIG. 1 ; 
           [0017]      FIG. 6  is a rear view of the brake control apparatus of  FIG. 1 ; 
           [0018]      FIG. 7  is an exploded view of the micro-adjust and macro-adjust mechanisms of the brake control apparatus of  FIG. 1 ; 
           [0019]      FIG. 8  is a top view of the mechanisms of  FIG. 7 ; 
           [0020]      FIG. 9  is a cross-sectional top view of the of the brake control apparatus of  FIG. 1 ; and 
           [0021]      FIG. 10  is a perspective rear view of the of the brake control apparatus of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Preferred embodiments of the invention will herein be described with reference to the drawings. It will be understood that the drawings and descriptions set out herein are provided for illustration only and do not limit the invention as defined by the claims appended hereto and any and all their equivalents. For example, the terms “first” and “second,” “upper” and “lower,” or “forward” and “rearward” are used for the sake of clarity and not as terms of limitation. Moreover, the terms may refer to bicycle mechanisms conventionally mounted to a bicycle and with the bicycle oriented and used in a standard fashion unless otherwise indicated. 
         [0023]    The figures illustrate a brake control apparatus  18  for a handlebar steered vehicle, such as a bicycle, including “triathlon” or “time trial” style bicycles, for example, according to an embodiment of the invention. All of many of the features may be adapted or incorporated into brake systems for other types of bicycles and the like. 
         [0024]    The brake control apparatus  18  includes a housing  20 , and a clamp mechanism  21 , which may clamp, the housing second section  20 B into an inside surface  29  of a handlebar  22  of the vehicle. It will be understood that the handlebar  22  is mountable to a bicycle and when so mounted may extend forwardly and receives the brake control apparatus  18  in an open end of the handlebar i.e., according to the direction of travel of the vehicle during standard forward operation. 
         [0025]    The brake control apparatus  18  increases and decreases fluid pressure in the apparatus to actuate the brakes. The brake control apparatus  18  may also include a micro-adjust mechanism  25  which operates to change the total fluid volume in the housing to adjust the clearance between the brake pads and a corresponding wheel rim (not shown). The brake control apparatus  18  may also include a macro-adjust mechanism  27  that quickly increases or decreases the clearance between brake pads and a wheel rim (preferably in one step or motion) to allow a rider to easily install and remove the wheel from the bicycle. 
         [0026]    The brake control apparatus  18  may include all or any of the master cylinder  69 ′, micro-adjust mechanism  25 , and macro-adjust mechanism  27  in a first section  20 A of the housing  20 . The clamp mechanism  21  may be considered to be attached to a second section  20 B of the housing  20 . 
         [0027]    The housing  20  may take a wide range of forms according to the desired overall shape of the brake apparatus and the desired elements and mechanisms housed therein or attached thereto. The housing  20  includes a master cylinder  69 ′ defined at least in part by a master cylinder bore  68 , which has a bore axis B that may be oriented transverse or perpendicular to the axis A of the handlebar  22  to which the housing is attachable. In embodiments where the bore  68  is transverse or perpendicular to the axis A of the handlebar, the master cylinder  69 ′ may be a radial master cylinder. The master cylinder  69 ′ may be spaced from the end of the bar. The handlebar axis A may intersect the master cylinder  69 ′. 
         [0028]    The master cylinder chamber  69  has a narrow diameter portion  71  ( FIG. 2A ) for housing spring  48 . At or near the top of the housing  20 , above the main part of chamber  69  and the narrow diameter portion  71  is a hole or bleed port  73  ( FIG. 2A ), which is normally occupied and closed by the bleed screw  50 , and may be opened to atmosphere to add or extract fluid or permit the escape of air. The bleed port  73  may have an undercut, and may be sealed with the housing by the screw  50  and an O-ring or the like, as is well known. 
         [0029]    At the forward end of the housing first section  20 A is an adjustment cylinder bore  70  at least in part defining an adjustment cylinder  75 ′ in fluid communication with the master cylinder  69 ′. The adjustment cylinder bore  70  may be angled, such that air is permitted to rise to and exit the bleed port  73 . Accordingly, the adjustment cylinder  75 ′ and master cylinder  69 ′ may communicate at or near an upper part of the housing  20  in a position such that air may rise to and then exit the bleed port  73  when the bleed port is open. 
         [0030]    In the first section of housing  20 A is formed a perpendicular or transverse hole  84  ( FIG. 2A ) (relative to axis A and B) formed through the housing, which is sized and shaped to receive a pivot pin  38  ( FIGS. 1 ,  3 - 6 ). An actuator  36  is pivotally carried on the pivot pin  38 . The actuator  36  may be a lever. The hole  84  is formed through the housing  20 A in a position that is relatively radially outboard from axis A and the position of the master cylinder bore  68 . Also the hole  84  may be considered to be between the master cylinder bore  68  and the adjustment cylinder bore  70 . 
         [0031]      FIG. 2A  is a cross section of the housing  20 . The adjustment cylinder bore  70  may have a threaded portion  90  to, permit a stop bolt  60  ( FIG. 1 ) to connect to the housing  20 . At or near an outermost portion of the adjustment cylinder bore  70 , which outermost portion may be a larger diameter than the more inwardly located bore portions, two or more rounded detents, cavities or indentations  74 , may be spaced apart, for example about 90 degrees, for interacting with a macro-adjust detent mechanism  62 . The macro-adjust detent mechanism  62  may include a ball  76  biased into the indentations  74  by a spring  78 , or the like. The macro-adjust detent mechanism  62  interacts with the detents or indentations  74  in the housing  20 , to releasably retain a macro-adjust lever  58  in a first or second position, dependent upon which one of the indentations are engaged by the macro-adjust detent mechanism. The positions correspond to relatively opened or closed positions of the brake pads (not shown). Thus, the macro-adjust detent mechanism  62  ensures that the macro-adjust mechanism  80  will not operate accidently. 
         [0032]    The passage  80  opening at the left end of the housing second section  20 B ( FIG. 2A ) may be internally threaded and is shaped and sized to receive a hydraulic line  34  and connector  32 . The passage  80  is in fluid communication with both the adjustment cylinder chamber  75  and the master cylinder chamber  69 . 
         [0033]    The right section  20 B (i.e., innermost end) of the housing  20  ( FIG. 1 ) has a first cone-shaped end  82  that may be tapered, e.g., cone-shaped as in a non-concave cone, with one or more optional anti-rotation features  86  ( FIG. 3 ), for example three radially extending ribs, where the clamp mechanism  21  is located. The housing  20 B may have flat surfaces  94  to receive a tool, such as a wrench, for tightening the hydraulic line connector  32 . 
         [0034]      FIG. 3  is a perspective view and  FIG. 4  is a cross-sectional view of an embodiment of a handlebar clamp mechanism  21  of the brake control apparatus  18 . The clamp mechanism  21  may be used to clamp a wide-range of devices to a handlebar, for example. The clamp mechanism  21  may be arranged symmetrically about housing second section  20 B and adjusted by an offset clamp adjuster  30 , which may include threaded screw  30 ′ and clamp nut  24  parts. The clamp mechanism also generally includes, in the illustrated embodiment, three mounting parts  24  and four friction rings  28 . It will be understood that other numbers of parts could be substituted for those illustrated. 
         [0035]    The clap screw  30 ′ extends through the housing  20  and is operatively coupled to the clamp nut  26 , in one embodiment by a threaded connection, to form a clamp adjustor  30 . The clamp nut  26  may have an inclined surface  83  at the left (facing the housing) in the form of a second cone-shaped surface that may cooperate with the housing second section  20 B inclined surface  82  ( FIG. 1 ). These two surfaces contact corresponding surfaces of the three mounting parts  24 , positioned between the nut  26  and housing second section  20 B. When urged together, the two surfaces  82 ,  83  tend to urge the structure interposed therebetween in a radially outward direction. The mounting parts  24  may be overwrapped and/or held by the friction rings  28 , which are positioned thereabout, and which also cause frictional contact between the mounting parts and the inner surface of the handlebar  22  when inserted therein. The clamp nut  26  extends at the right side ( FIG. 1 ) a distance sufficient to distribute the side load created by the radial offset of the adjustor screw  30 ′ from the axis A shared by the clamp nut (see  FIGS. 1 ,  3 , and  4 ). 
         [0036]      FIG. 5  shows the front view and  FIG. 6  shows the back view of the housing  20  and brake actuator  36 . In particular, the offset adjuster screw  30 ′ can be seen in  FIG. 5  set in the first section  20 A and extending through and along the second section  20 B to operate the clamp mechanism  21  when the screw is rotated in the illustrated embodiment. 
         [0037]      FIG. 1  is an embodiment of the brake control apparatus  18  including an actuator  36 , a pivot pin  38 , a rod pin  40 , a rod  42 , a master piston  44 , a spring  48 , a bleed screw  50 , and two stop pins  46 . The actuator  36  pivots on the pivot pin  38 , which pin may be fixed to the housing  20 . The rod pin  40  is attached to the actuator  36  and the rod  42  is adjustably engaged with the rod pin. The rod  42  operatively connects the actuator  36  to the master piston  44  and may be a threaded connection on the end adjacent the actuator  36  and a ball and socket type connection on the opposite side with the master piston  44 . 
         [0038]    The master piston  44  is slidably disposed in the master cylinder bore  68  and at least in part with the bore defines the master cylinder chamber  69  and thus the master cylinder  69 ′. The master piston  44  may be sealed to the bore  68  with a backup ring and an O-ring, as is well known, to seal hydraulic fluid in the master cylinder chamber  69 . At an outer end of the master cylinder chamber  69  may be a pair of transverse or perpendicular holes formed in the housing for receiving stop pins  46 , e.g., two pins, which prevent the ball end of the rod  42  from coming out of the bore  68  by being spaced apart a distance less than the diameter or the ball end. The pins  46  also function to prevent the master piston  44  from backing out of the master cylinder bore  68 . The pins  46  may be any suitable structure or means of preventing the exit of the master piston  44  from the master cylinder. The spring  48  is positioned inside the master cylinder chamber  69  to bias the master piston  44  in a direction out of the chamber. The master piston  44  may have a portion which is a smaller diameter than the inner diameter of the spring  48  and thus may function to hold the spring. The upper end  71  of the master cylinder bore  68  has a larger inner diameter than the outer diameter of the spring  48  and thus may house the spring at the upper end. At the top of the master cylinder bore  68  is a hole  73  formed through the housing, which may be threaded for receiving the bleed screw  50  and at the end of this threaded hole may be a round undercut for an O-ring (not shown), which seals the hydraulic fluid in the master cylinder chamber  69  with the bleed screw. 
         [0039]      FIGS. 7-10  show the micro-adjust mechanism  25  and parts of the macro-adjust mechanism  27 , including an adjustment piston  52 , an adjustment screw  54 , a quick release slider  56 , a stop bolt  60 , a macro-adjust lever  58 , and an adjuster  64 , which may be in the form of an adjustment wheel or knob, a macro-adjust detent mechanism  62 , and an adjustment wheel detent mechanism  66 . While the micro-adjust mechanism  25  and the macro-adjust mechanism  27  are shown on the first section  20 A of the housing, the location ma y  be modified to accommodate other types of control devices. 
         [0040]    The adjustment piston  52  is slidably disposed in the adjustment cylinder bore  70 , and at least in part defines with the bore the adjustment chamber  75  and thus the adjustment cylinder  75 ′ and may be sealed with a backup ring and an O-ring, as is known with hydraulic brake systems in general. The adjustment piston  52  moves to increase and decrease the oil volume in the adjustment cylinder chamber  75 , and thus the total combined fluid volume in the adjustment cylinder chamber and master cylinder chamber  69 , dependent upon its position and direction in the bore  70  ( FIG. 2 ). The adjustment piston  52  may have a threaded blind hole  87  at the outer-facing side and a smaller outer diameter  88  at an opposite end that fits to the inner end of the adjustment cylinder bore  70 . The adjustment screw  54  is rotatably disposed through the macro-adjust slider  56  and may be fixed against axial movement in the slider  56  with a flange like stop  92  at the inside and with the clamped adjustment wheel  64  at the outside. This adjuster  64  may be any suitable shape, knob, lever or the like that is graspable and/or movable by a user and may be fixed to the adjustment screw  54  with a set screw or any suitable fastening means. The adjustment screw  54  may be threaded above the stop  92  and thus threadably engaged with the adjustment piston  52 . 
         [0041]    The macro-adjust lever  58  may be fixed to the macro-adjust slider  56  with a set screw or any suitable fastening means and the macro-adjust slider can slide and turn inside the stop bolt  60 . The macro-adjust slider  56  is shown connected to the stop bolt  60  with a cam follower connection  98  including two sliding surfaces which are perpendicular to the adjustment cylinder bore  70 . Rotation of the macro-adjust lever  58  rotates the cam shaped mounting surface  98  between the inner side of the stop bolt  60  and the adjustment piston  52  causes an axial movement of piston  52 . 
         [0042]    The macro-adjust lever  58  may include the radially operating macro-adjust detent mechanism  62 . This mechanism includes a spring  78  which pushes a ball  76  into one of two or more round grooves or detents  74  of the housing  20  and may hold the macro-adjust lever  58  into the detent. The detents  74  are spaced apart, for example about 90 degrees. The adjustment wheel  64  also may have an axially operating adjustment wheel detent mechanism  66 . This mechanism is also built up of a spring  94  which pushes a ball  96  into a V-shape groove or detent  98  at the outer side or face of the quick release lever  58  and holds the adjustment wheel  64  at one of a number of rotational positions, e.g., eight positions in one complete rotation. 
         [0043]    The brake apparatus  18  is secured to the handlebar  22  by inserting the second section  20 B into the open end of the handlebar and operating the adjuster  30 . The threads inside the clamp nut  26  convert the circular motion of the adjustor screw  30 ′ into an axial movement and the cone shaped surface of the clamp nut  26  pushes at the adjacent cooperating surfaces of the mounting part  24 . The other of the cooperating surfaces of the mounting part  24  push against the cone shaped surface  82  of the housing second section  20 B. The axial movement of the clamp nut  26  caused by the respective surfaces is converted into an outwards movement of the mounting parts  24 . The elastic friction rings  28  will also move radially on the mounting parts  24  and will be pressed between the mounting parts and the inside surface  29  of the handlebar  22  to increase the clamping force therebetween. Tightening of the offset adjuster screw  30 ′ increases the force between the mounting parts  24  and the inner surface of the handlebar  22  which causes a secure friction fit between the housing  20  and the handlebar  22 . If the offset adjuster screw  30 ′ is turned to loosen, the clamp nut  26  makes an axial movement to the right and the mounting parts  24  are pushed radially inwardly by the friction rings  28 , thus the friction fit is released and the housing  20  can be removed from the handlebar  22 . The rings  28  are not necessary to the clamp mechanism, but embody one embodiment, and do function to add friction. 
         [0044]    Operation of the actuator  36  creates a torque which causes the actuator to pivot around the pivot pin  38 . The load is transferred through the rod pin  40  into the rod  42  and urges the master piston  44  into the bore  68  and thus the master cylinder chamber  69 . The master piston  44  pushes against the bias of spring  48  and causes the flow of hydraulic fluid through the hydraulic line  34  into the brake caliper (not shown) until the brake pads (not shown) contact the rim. Upon pad contact with the rim, the master piston  44  does not appreciably continue to move and the force of the pads on the rim increases correspondingly with the increase of the pressure of the hydraulic fluid. The spring  48  is also axially compressed during this process and when the hand load is reduced, the spring uses the stored energy created during compression to urge the master piston  44  back until the ball end of the rod  42  comes to rest in contact with the two stop pins  46 . 
         [0045]    Operation of the micro-adjust mechanism  25  provides for increases and decreases in the total hydraulic fluid volume of the housing  20  in order to adjust the clearance between the brake pads and the rim (not shown). The brake apparatus  18  preferably has two different operating adjustment controls with different feed motions. The macro-adjust mechanism  27 , which causes a relatively large feed motion of the adjustment piston  52  by rotating the macro-adjust lever  58  a select amount, e.g., 90 degrees, and the micro-adjust mechanism  25 , which causes a lesser feed motion of the adjustment piston  58  by turning the adjustment wheel  64 . 
         [0046]    The macro-adjust mechanism  27  increases or decreases the clearance between the brake pads and the rim, e.g., in one step, to allow the rider to remove a wheel from the frame. By turning the macro-adjust lever  58 , e.g., about 90 degrees, the sliding surface  98  between the macro-adjust slider  56  and the mounting surface of the stop bolt  60  and causes an axial movement of the macro-adjust slider  56 , the macro-adjust lever  58 , the adjustment screw  54 , the adjustment wheel  64  and the adjustment piston  52 . 
         [0047]    During this process operated in the release direction, the fluid volume of the housing  20  increases and hydraulic fluid is pulled in through the hydraulic line  34  and out of the brake caliper. This causes movement of the slave piston in the brake caliper (not shown) and the brake pads to open up (i.e., the space between respective brake pads) in order to provide the clearance to remove or install the wheel out of or into the vehicle frame. 
         [0048]    By turning the macro-adjust lever  58  in the opposite direction from that described above, the sliding surface of the macro-adjust slider  56  follows the mounting surface  98  of the stop bolt  60  and causes an axial movement in the other direction and the fluid volume of the housing  20  decreases and fluid is pushed back into the brake caliper causing the pads to move together. Both positions of the macro-adjust lever  58  may be retained with the macro-adjust detent mechanism  62 . The spring  78 , which may be located in the macro-adjust lever  58 , pushes a ball  76  into a round groove  74  of the housing  20  and the angular position of the macro-adjust lever  58  may be thus retained. Before turning the macro-adjust lever  58  to another position, the torque needs to overcome the spring force of the macro-adjust detent mechanism  62 , which urges the ball  76  into the groove  74  of the housing  20 . 
         [0049]    The micro-adjust mechanism  25  also provides a pad contact adjustment with an appropriate, lesser feed motion (relative to the macro-adjustment mechanism for a select amount of rotation thereof) by turning the adjustment wheel  64  a selected amount. It will be understood that for any given or select amount of rotation that the macro-adjust mechanism  27  will produce a relatively greater motion of the piston  52  than the micro-adjust mechanism  25 . 
         [0050]    The adjustment wheel  64  is connected to the adjustment screw  54 , which is rotatably connected to the adjustment piston  52  by a threaded connection. The threads convert the rotational motion of the wheel  64  into an axial motion of the adjustment piston  52  and the fluid volume of the housing  20  increases or decreases depending upon the rotational direction of the adjustment wheel  64 , producing a corresponding change in distance between the brake pads and the rim (not shown). The angular position of the adjustment wheel  64  may be movably retained in a number of positions by the adjustment wheel detent mechanism  66 . The spring  94  of the detent mechanism  66  urges a ball  96  into the V-groove  98  of the macro-adjust lever  58  and the torque needs to be higher than the spring force to turn the adjustment wheel  64 . 
         [0051]    In one embodiment, the macro-adjust detent mechanism  62  includes a stronger spring retention arrangement than that of the adjustment wheel detent mechanism  66 , such that the adjustment wheel  64  does not carry and turn the macro-adjust lever  58  when the adjustment wheel is turned. 
         [0052]    While this invention has been described by reference to particular embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the disclosed embodiment, but that it have the full scope permitted by the language of the following claims.