Abstract:
A locomotive brake system includes a brake cylinder with an integrated parking brake; a main reservoir; and a brake system controller for controlling the pressure in the brake cylinder. The brake system uses main reservoir pressure to pressurize the brake cylinder to achieve the parking brake output force using the brake cylinder.

Description:
BACKGROUND AND SUMMARY 
     The present locomotive brake system is directed to a combined brake cylinder and parking brake. An example is shown in US published application US 2005/0092563 dated May 5, 2005. 
     For this arrangement, the parking brake lock mechanism is located to the pressurized side of the brake cylinder, which allows the use of a conventional hollow rod to support the brake cylinder push rod. The parking brake lock actuating rod is loosely connected to the pressure side of the brake cylinder piston, so that when actuated it prevents the release of the pneumatic brake force, while the “loose” connection allows for some misalignment during operation, preventing unnecessary wear or binding. 
     In the present locomotive brake cylinder with parking brake lock is a locomotive brake cylinder with a parking brake locking mechanism to provide a parking brake function. The parking brake locking mechanism mechanically locks the brake cylinder in the applied position after a pneumatic brake application from the locomotive brake system. The parking brake locking mechanism is controlled by a pneumatic pilot signal from a main reservoir on the locomotive. The parking brake is enabled when the pilot pressure is removed, and disabled and/or released when the pilot pressure is applied. 
     The present locomotive brake system includes: a brake cylinder with an integrated parking brake; a main reservoir; and a brake system controller for controlling the pressure in the brake cylinder. The brake system uses main reservoir pressure to pressurize the brake cylinder to achieve the parking brake output force using the brake cylinder. 
     These and other aspects of the present system will become apparent from the following detailed description of the system, when considered in conjunction with accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic of a first embodiment of a locomotive parking brake according to the present disclosure. 
         FIG. 2  is a schematic of a second embodiment of a locomotive parking brake according to the present disclosure. 
         FIG. 3  illustrates the various conditions of operation of the locomotive parking brake system according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     As illustrated in  FIG. 1 , the brake cylinder  10  has a port  12  and includes a parking brake locking mechanism  14  with a port  16 . A locomotive brake system controller  20  includes a brake cylinder relay  22  which provides a brake pressure to the brake cylinder  10  from the main reservoir MR proportional to a brake signal BS or release using exhaust EX. The locomotive brake system controller may be a CCB® brake system from New York Air Brake and shown in U.S. Pat. Nos. 5,172,316 and 6,098,006 or any other system. 
     An electrically controlled parking brake control valve  30  is provided and includes a solenoid valves V 1  and V 2 . In a first position shown in  FIG. 1 , the solenoid valve V 1  applies main reservoir pressure to the parking brake lock pilot port  16  and simultaneously via solenoid valve V 2  connects the brake cylinder port  12  to the brake cylinder signal BRK from the brake cylinder relay  22  of the locomotive brake system controller  20 . This first position provides parking brake release and normal pneumatic brake function. In a second position, the valve V 1  will vent the parking brake lock pilot port  16  to atmosphere and valve V 2  will pressurize the pneumatic brake cylinder port  12  with main reservoir pressure MR. 
     The parking brake lock mechanism  14  will mechanically lock the brake cylinder  10  at the full output force, even if the MR pressure to the brake cylinder  10  is subsequently exhausted. The parking brake will be released when the parking control valve  30  is commanded back to the first position. The parking control valve  30  is responsive to the parking brake lock signal PBC at  32  from an operator input. The various conditions of operation are shown in  FIG. 3 . 
     Unlike the parking brake lock for rail cars, main reservoir pressure MR is used to energize the system to provide higher parking brake forces than would be possible with typical service and emergency brake pressures from the brake cylinder relay valve  22 . By using the main reservoir pressure MR as the actuating pressure, a very compact, high output automatic parking brake is achieved. Further, because the brake cylinder signal BRK is controlled by the locomotive brake system controller  20 , like CCB® brake system, which provides closed loop pressure control of the brake pressure, any undesired main reservoir leakage from the parking control valve  30  to the brake cylinder  10  will be automatically exhausted by the locomotive brake system controller  20 , making the system very fault tolerant. 
     As further embellishment of the parking brake system for locomotive according to the present invention is illustrated in  FIG. 2 , when the brake cylinder  10  with parking locking mechanism  14  is installed on a locomotive that is also equipped with the locomotive brake system controller  20  (e.g., a computer controlled brake system, then the locomotive brake system controller  20  could be commanded by an electrical switch PBC  40 . PBC  40  may be operated by the driver, via dotted line  42  to pressurize the brake cylinder to MR pressure, or other selected pressure as needed to provide the required parking brake force, directly from the brake cylinder relay  22 . The parking brake lock pilot pressure could similarly be controlled by the locomotive brake system controller  20  using the solenoid valve V 1 . The solenoid valve V 2  is eliminated. 
     Integrating the control PBC  40  of the parking brake with the locomotive brake system controller  20  also reduces the opportunity for operator error by integrating two otherwise independent systems and providing the necessary interlocks and diagnostics to prevent the inadvertent attempt to drive the locomotive with the parking brake set, for example. In addition, the parking brake application and release could be controlled by the operator through the existing operator display screen, thus eliminating unnecessary wires, switches, sensors, etc. Thus, by integrating the function of the parking brake with the locomotive brake system controller  20 , the function of the parking brake lock control valve  30  is provided in a less costly way. 
     On a parked, “dead” locomotive, without sufficient MR pressure, the parking brake can be manually released with a ¼-turn release nut. In this case, each parking brake locking mechanism  14  on the locomotive would have to be independently released manually. The parking brake locking mechanism  14  automatically resets when it is re-pressurized. 
     Although the present system has been described and illustrated in detail, it is to be clearly understood that this is done by way of illustration and example only and is not to be taken by way of limitation. The scope of the present system is to be limited only by the terms of the appended claims.