Abstract:
A wheel brake cylinder adjuster includes a gas in a gas chamber, a piston, a push rod, a positioning portion, a stop plate, a control module, and several relief holes. They are connected so that the gas pushes the piston to move the push rod. A gas adjusting module is employed to relieve the gas. The invention achieves the goals of having a simple structure, a lower cost, and the function of re-positioning the push rod.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The invention relates to an adjuster for the wheel brake cylinder and, in particular, to a wheel brake cylinder adjusting device with a simple structure for re-positioning its push rod and reducing the production cost. 
         [0003]    2. Related Art 
         [0004]    The brake is an important function for operating a vehicle. With the driver&#39;s stepping on the brake, the wheel brake cylinder gradually exposes itself as the brake lining wears out. When the braking distance of the vehicle becomes longer, it means that the braking lining needs to be replaced. In this case, the wheel brake cylinder axis has to be rotated and pushed to its original position for replacement. 
         [0005]    The conventional brake cylinder adjuster is shown in  FIG. 4 . It includes a block  7  having a first end installed with a fixing plate  71  and a second end; a handle  72  with one end connected to the second end of the block  7  and the other end connected with a connector  721 ; a push rod  73  penetrating through the block  7  and the handle  72  with one end provided with a pushing plate  731  for pressing against the brake cylinder and the other end provided with a lever  732  for rotating the push rod  73 ; an inlet valve  74  disposed on one side of the handle  72  for selectively controlling high-pressure gas to enter the block  7  via the connector  721 , thus pushing a piston (not shown) and displacing the push rod  73 ; a relief valve  75  disposed on the other side of the handle  72  for releasing the high-pressure gas inside the block  7  so that the push rod  73  can be readily pulled back to its initial position. 
         [0006]    However, the brake cylinder adjuster with the relief valve has a complicated structure. Correspondingly, its production cost is more expensive. It is thus highly desirable to improve its structure. 
       SUMMARY OF THE INVENTION 
       [0007]    An objective of the invention is to solve the foregoing problems and provide a brake cylinder adjuster. It uses a relief hole provided in a gun pipe to achieve the goal of re-positioning the push rod. 
         [0008]    Another objective of the invention is to simplify the relief component of the adjuster. The combination of a relief hole and a gas adjusting module achieves the goal of releasing gas. Therefore, the invention has the advantages of a simpler structure and a lower production cost. 
         [0009]    To achieve the above objectives, the invention includes a gun body, a control module, a positioning portion, a push rod, and a stop plate. 
         [0010]    The gun body has to gun pipe and a handle portion for the flow of gas. The gun pipe has a first accommodation space inside. The outer rim of the gun pipe has several relief holes. A gas adjusting module is disposed in one of the relief holes. The handle portion extends downward and connects to the rear end of the gun pipe. The handle portion has a gas chamber and a second accommodation space inside. A first gas channel is formed between the second accommodation space and the gas chamber. A second gas channel is formed between the second accommodation space and the first accommodation space. 
         [0011]    The control module is disposed inside the second accommodation space for controlling gas to flow from the second accommodation space to the first accommodation space. The positioning portion is mounted on the end of the gun pipe opposite to the handle portion. The push rod penetrates through the gun body and protrudes from both ends. A lever is disposed near the rear end of the push rod. The outer side of the push rod is disposed in sequence the positioning portion, a piston, and the lever. The stop plate is connected to the front end of the push rod and has several bumps. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention will become more fully understood from the detailed description given herein below illustration only, and thus is not limitative of the present invention, and wherein: 
           [0013]      FIG. 1  shows the appearance of the invention; 
           [0014]      FIG. 2  is a cross-sectional view of the invention; 
           [0015]      FIG. 3  schematically depicts how the invention works; 
           [0016]      FIG. 4  is a locally enlarged view showing the relation between the gas adjusting module and the relief hole; 
           [0017]      FIG. 5  is another locally enlarged view showing the relation between the gas adjusting module and the relief hole; and 
           [0018]      FIG. 6  is a schematic view of the relief valve in the conventional wheel brake cylinder. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
         [0020]    A preferred embodiment of the brake cylinder adjuster according to the invention is shown in  FIGS. 1 and 2 . It includes a gun body  1 , a control module  3 , a positioning portion,  4  a push rod  5 , and a stop plate  6 . 
         [0021]    The gun body  1  has to gun pipe  11  and a handle portion  12  for the flow of gas therein. The gun pipe  11  has a first accommodation space  111  inside. The outer rim of the gun pipe  11  has a first relief hole  112 , a second relief hole  113 , and a third relief hole  114 . The second relief hole  113  and the third relief hole  114  subtend an angle ?. The second relief hole  113  and the third relief hole  114  are connected at the intersection with the first accommodation space  111 . A gas adjusting module  2  is disposed in the second relief hole  113 . In this embodiment, the gas adjusting module  2  consists of a locking element  21 , an elastic element  22 , and a steel ball  23 . The handle portion  12  extends downward and connects to the rear end of the gun pipe  11 . The handle portion  12  has a connector  125  and a gas chamber  121  and a second accommodation space  122  inside. A first gas channel  123  is formed between the second accommodation space  122  and the gas chamber  121 . A second gas channel  124  is formed between the second accommodation space  122  and the first accommodation space  111 . 
         [0022]    The control module  3  is disposed inside the second accommodation space  122  for controlling gas to flow from the second accommodation space  122  to the first accommodation space  111 . The control module  3  includes a pressing board  31 , an action rod  32 , a spring  33 , and a push element  34 . The spring  33  is mounted on the rear end of the action rod  32 . The push element  34  is mounted on the front end of the action rod  32 . The front end of the action rod  32  protrudes from the push element  34  and pushes against the pressing board  31 . 
         [0023]    The positioning portion  4  is mounted on the end of the gun pipe  11  opposite to the handle portion  12 . 
         [0024]    The push rod  5  penetrates through the gun body  1  and protrudes from both ends. A lever  51  is disposed near the rear end of the push rod  5 . The outer side of the push rod  5  is disposed in sequence the positioning portion  4 , a piston  52 , and the lever  51 . 
         [0025]    The stop plate  6  is connected to the front end of the push rod  5  and has several bumps  61 . 
         [0026]    When using the invention, the user first fills a gas into the gas chamber  121  from a gas source (not shown). After the gas chamber  121  is filled with the gas, it flows from the gas chamber  121  to the second accommodation space  122  via the first gas channel  123  in between. The bumps  61  are in line with the left-handed or right-handed screw thread of the brake cylinder and pushes against the pressing board  31 . The pressing board  31  moves the action rod  32  backward in the second accommodation space  122 . During the backward motion of the action rod  32 , the gas flows via the second gas channel into the first accommodation space  111 . Since the steel ball  23  is disposed at the intersection of the second relief hole  113 , the third relief hole  114 , and the first accommodation space  111 , the gas is prevented from leaking out via the third relief hole  114 . The gas then pushes the piston  52  to move the push rod  5  forward. As shown in  FIG. 3 , the bumps  61  are positioned. The user can rotate the lever  51  to rotate the screw thread. 
         [0027]    After the action of rotating the screw thread is done, the gas inside the first accommodation space  111  pushes the steel ball  23  upward to pull the push rod  5  back to its initial position. The steel  23  no longer blocks the intersection of the second relief hole  113 , the third relief hole  114 , and the first accommodation space  111 , as shown in  FIGS. 4 and 5 . Therefore, the gas leaks out via the third relief hole  114 , instead of pushing the piston  52 . In this case, the user pulls the lever backward, thus readily brining the push rod  5  backward to its initial position. 
         [0028]    In summary, the invention utilizes a gas to push the piston and the push rod. The push rod moves the bumps on the stop plate to rotate the lever, thereby driving the wheel brake cylinder. The combination of the relief holes and the gas adjusting module according to the invention can achieve the action of releasing the gas. Therefore, the invention has the advantages of a simple structure, a lower production cost, and re-positioning the push rod. 
         [0029]    Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.