Abstract:
A test system is provided for primary and secondary brakes in a vehicle. The test system includes a two-position combination first valve having a first inlet coupled to a primary air supply, a second inlet coupled to a test air supply, and an outlet coupled to the primary brakes. The test system also includes a two-position combination second valve having a first inlet coupled to a secondary air supply, a second inlet coupled to the test air supply, and an outlet coupled to the secondary brakes. A system selector switch is provided for selectively applying current to one or both of the first and second valves responsive to a test signal input wherein each of the first and second valves directs fluid flow from one of the first and second inlets to the outlet.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to vehicle brake test systems and, in particular, to vehicle brake test systems for automotive vehicles, such as trucks having primary and secondary air brake systems. 
     2. Discussion of Related Art 
     Large tractor-trailer type trucks have air actuated brakes that are divided into primary and secondary systems. A secondary brake system is typically provided for the directional steering axle wheels of the vehicle. A primary brake system is typically provided for braking the drive axle wheels of the vehicle. 
     When testing a vehicle with air actuated brakes having a primary and secondary system, it is typically required that the brakes be applied at a consistent set pressure for many successive brake applications or stops. The air brake system must typically be tested while functioning under a wide pressure supply range. The pressure supply range can easily vary between 5-120 psi. 
     It is also often desirable that the vehicle brake system be tested utilizing only the secondary brake system or the primary brake system. Often, the brake system of vehicles is tested in a real life environment on an outdoor test track. When the vehicle is tested at low air pressures, the vehicle&#39;s deceleration is at a slower pace with expanded stopping distances. During a slow pace deceleration, unanticipated events may occur, which require immediate emergency override of the system, such as a deer or another test vehicle in the vicinity. If an unanticipated event does occur, it is desirable to allow the vehicle operator to immediately utilize the brakes at their maximum capacity. 
     SUMMARY OF THE INVENTION 
     To make manifest the above delineated and other desires, a revelation of the present invention is brought forth. In a preferred embodiment, the present invention provides a test system for a vehicle having primary and secondary air brakes. 
     A first valve is provided. The first valve has a first inlet coupled to a primary air supply and a second inlet coupled to a test air supply. An outlet of the first valve is coupled to the brakes of the primary brake system of the vehicle. 
     A second valve is provided. The second valve has a first inlet coupled to a secondary air supply. The second valve also has a second inlet coupled to the test air supply. The second valve has an outlet coupled to the brakes of the secondary brake system of the vehicle. 
     A system selector switch assembly is provided. The system selector switch assembly selectively provides current to one or both of the first and second valves responsive to an operator input wherein each of the first and second valves directs fluid flow from one of the first and second inlets to the outlet. 
     There is additionally provided an override switch which will cause the first and second valves to couple their first inlet with their outlet, regardless of a selected position of the selector switch assembly. The override switch will typically be actuated by the operator of the vehicle utilizing the brake pedal (commonly referred to as the treadle). 
     Advantages of the present invention will be further explained as the invention is revealed in the accompanying drawings and detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a vehicle air brake test system prior to the present invention. 
     FIG. 2 is a schematic view of a vehicle air brake test system according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Prior to the present invention, a vehicle test system  3  included an air tank  5 . The air tank  5  is connected to an air line  7 , which is in turn connected to a pressure regulator valve  9 . An air line  11  is provided. The air traveling through air line  11  is controlled by a primary treadle (not shown). The source of the air flowing through the air line  11  is the air tank  5  via the vehicle brake treadle valve (not shown). 
     Air from the air line  11  is controlled by a ball valve  13 . The ball valve  13 , which is preferably electrically or, in other cases manually actuated, is connected to an output air line  15 . Output air line  15  is connected to a reverse-flow check valve  17 . Check valve  17  is connected to an air line  19 . Air line  19  is connected with a teed connection  21 . The teed connection  21  is connected to a primary brake apply line  23 . The apply line  23  is connected to a brake chamber  25  of the primary brake system. The teed connection  21  is also connected to a first test air supply check valve  27 . The check valve  27  is fluidly connected to a normally closed ball valve  29 . The ball valve  29  is fluidly connected to an air line  31 , which is teed to the outlet of the regulated supply  33 . 
     In a manner similar to that aforedescribed, an air line  35  is connected to a normally open ball valve  37 , which in turn, connects to an air line  39 . The air line  39  is connected to a reverse flow check valve  41 . The check valve  41  is connected to an air line  43 . The air line  43  is connected with a teed connection  45 . The teed connection  45  is connected to an air line  47 . The air line  47  is connected to the brake chambers  49  of the secondary brake system. The teed connection  45  is connected to a check valve  51 , which is connected to a normally open ball valve  53 . The ball valve  53  is connected with an air line  55 , which is teed to the outlet of the regulated supply  33 . 
     The air line  35  is controlled by the vehicle secondary treadle and is supplied with pressurized air from the air tank  5  through the normal vehicle air system (not shown). When a vehicle operator utilizes the brake test system  3 , the ball valves  13 ,  37  have to be actuated to a closed position or, if manual ball valves are provided, have to be manually switched to the closed position. 
     If it is desirable to test the primary brake system, the system selector switch will control ball valve  29  to open while simultaneously controlling ball valve  13  to close when the regulated apply switch is actuated. If it is desirable to test the secondary brake system, the system selector switch will control ball valve  53  to open while simultaneously controlling ball valve  37  to close when the regulated apply switch is actuated. If it is desirable to test both the primary and the secondary brake systems together, the system selector switch will control both ball valves  29  and  53  to open while simultaneously controlling ball valves  13  and  37  to close. 
     It should be noted that many standard ball valves are configured to exhaust the high-pressure side when the valve is in a closed position. Accordingly, check valves are required so that regulated pressure does not flow backwards through the exhaust of the closed ball valve during a regulated pressure or normal braking operation. 
     The brake test system  3  does not provide an emergency override to reconnect the primary treadle valve and the secondary treadle valve with the primary and secondary brake systems in an emergency brake operational situation. 
     Referring to FIG. 2, a vehicle air brake test system  70  according to the present invention is provided. Test system  70  has a two-position combination first valve  72 . The first valve  72  is spring biased to a position wherein its first inlet  74  is coupled to the primary treadle air line  76 . The first valve  72  has an outlet  78  which is connected to an air line  80 , which is connected to brake chamber  82  of the primary brake system. 
     When energized to a nonbiased position, the first valve  72  will connect its second inlet  84  to its outlet  78 . The second inlet  84  is connected to an air line  86 , which through a teed connection  88 , is connected to a variable pressure regulator valve  90 . The valve  90  is connected via line  92 , to the vehicle air tank  94 . 
     A two-position combination second valve  96  is provided. In a manner similar to that of the first valve  72 , the second valve  96  is biased to place a first inlet  98  in a coupled position with outlet  100 , which is connected to an air line  102  which is fluidly connected to brake chambers  104  of the secondary brake system. The first inlet  98  is coupled to a secondary treadle air line  75 . The valve  96  also has a second inlet  106  that can place its outlet  100  in a fluid connection with an air line  108 , which is further connected to the teed connection  88 . 
     The vehicle battery  112  is utilized to electrically actuate the valves and apply the brakes when the regulated test air apply switch  114  is activated. The switch  114  is electrically connected to a system selector switch assembly  116 . The assembly  116  is responsive to a selector input, placing it in a first position  118 , second position  120 , or third position  122 . 
     In first position  118 , the system selector switch  116  actuates the first valve  72  in a position to connect the first valve second inlet  74  to the brake chambers  82  of the primary brake system. 
     In second position  120 , the system selector switch  116  connects the second valve  96  to place its second inlet  98  in fluid connection to the brake chambers  104  of the secondary brake system, while the first valve  72  is in its biased position, wherein the first inlet  74  is in fluid communication with the brake chambers  82  of the primary brake system. 
     In third position  122 , both the first and second valves  72 ,  96  will be moved to connect their respective second inlets  84 ,  106  with the test air supply provided by the regulator valve  90 . 
     The system selector switch assembly  116  electrically actuates the first valve  72  via a first emergency override relay  130 . A second emergency override relay  132  controls current flow to the second valve  96 . 
     In operation, as mentioned previously, when the system selector switch is in the first position  118  or third position  122 , the primary brake system is in fluid connection to the test air supply which flows through the regulator valve  90 . In the second position  120  or third position  122 , the secondary brake system is in fluid connection to the test air supply which flows through the regulator valve  90 . 
     Typically, the operation of the system selector switch  116  will be responsive to an operator input. The test system will only be activated by actuation of the regulated test air apply switch  114 . The pressure regulator is adjusted by the vehicle operator inside the vehicle&#39;s cab. 
     Typically, the vehicle operator will be assigned to make a predetermined number of brake stops at a defined pressure. These stops will occur automatically at the selected air pressure by initiating the switch  114 . Closing switch  114  also supplies current to the right hand terminal of the emergency disable switch assembly  136  via an electrical line  138 . 
     In an emergency situation, as the emergency disable switch assembly  136  is closed, relay coils  140 ,  142  are activated, thereby open-circuiting emergency relays  130 ,  132 . The energized valves  72 ,  96  or both, depending on the position of the selector switch, are de-energized returning them to their normal position connecting their respective first inlets  74 ,  98  to the normal brake apply pressure lines provided by air line  76  and air line  102  and normal operation of the secondary and primary brake systems will be effected. 
     Typically, the switch assembly  136  will be operatively associated with the brake pedal of the vehicle so that the normal operator action will cause the activation of the disable switch assembly  136 . 
     An embodiment of the present invention has been shown. However, it will apparent to those skilled in the art of the various modifications which can be made to the present invention without departing from the spirit or scope of the invention as it is encompassed by the following claims.