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Empty and load apparatus for railroad cars

  • US 4,423,909 A
  • Filed: 10/30/1981
  • Issued: 01/03/1984
  • Est. Priority Date: 10/30/1981
  • Status: Expired due to Term
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First Claim
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1. In empty and load air brake control apparatus for use in railroad cars of the type having a sprung car body portion resiliently supported in sprung relation to an unsprung portion of the car and including a brake pipe normally charged with braking air under pressure, a reservoir normally air charged to the pressure of the air in the brake pipe, a brake cylinder for effecting a braking application, an air pressure responsive brake application control valve operative in response to pressure decreases in the brake pipe to control the supply of braking air under pressure from said reservoir to said brake cylinder through air conduit means for causing a brake stroke application and including a retainer device for venting the braking air that effects the braking stroke to atmosphere through the air conduit means, on completion of the brake application in response to pressure increases in the brake pipe, with the air conduit means including a modulating valve for changing the pressure of the supply of the braking air to the brake cylinder between that appropriate for load conditions and that appropriate for empty conditions, a stop carried by the unsprung portion of the car, and a load sensing device carried by the car body sprung portion adjacent the stop and including a load sensing member movable for engagement with the stop on the brake stroke application for controlling the pressure changing of the modulating valve in accordance with the car body being under empty or load conditions,the improvement wherein:

  • said modulating valve comprises;

    housing means defining a cavity across which is mounted a differential valve member forming a first full braking pressure chamber on one side thereof and a second partial braking pressure chamber on the other side thereof,a valve seat opening to said first chamber against which said valve member may seat to close off fluid flow through said seat,said valve member having exposed in said chambers on either side of same working areas of which the working area exposed to said second chamber is greater than the working area of same that is exposed to said first chamber by a predetermined ratio, whereby when said chambers are subject to fluid pressure in said passages, said valve member will be subject to a differential pressure force biasing same toward said seat,means for biasing said valve member away from said seat,said air conduit means including first pipe means communicating between said control valve and said modulating valve first chamber for supplying braking air at full braking pressure thereto and venting same through the retainer device, second pipe means communicating between said modulating valve seat and the brake cylinder for communicating said braking air between said valve seat and the brake cylinder, and third pipe means including a volume reservoir communicating between said modulating valve second chamber and said second pipe means through the load sensing device for supplying braking air at the partial braking pressure to the brake cylinder when said valve member closes said valve seat,said load sensing device comprising;

    a casing including piston means for actuating said load sensing member, with said casing defining a first chamber in open communication with one side of said piston means,said second pipe means being in communication with said casing first chamber for communicating said braking air thereto for moving said piston means to shift said load sensing member toward its extended relation,means for biasing said load sensing member to its retracted relation that yields when the pressure of the braking air in said casing first chamber is on the order to fifteen psi,said casing defining a second chamber spaced and isolated from said piston means with said third pipe means communicating with said casing second chamber,a check valve assembly interposed between said casing chambers and including means for biasing same in closed relation for maintaining said casing first chamber sealed off from said casing second chamber on operation of said apparatus when the car body is under load conditions,and linkage means actuated by said piston means for opening said check valve assembly to communicate said casing second chamber to said casing first chamber when the car body is under empty conditions,said linkage means comprising a fulcrumed lever device having one end of same in lost motion relation to said piston means for fulcruming actuation thereby when said load sensing member has moved to its extended relation for biasing said check valve assembly to open relation,said check valve assembly biasing means having a biasing action opposing the biasing action of said lever device that holds said check valve assembly in closed relation when the pressure of said braking air in said casing first chamber is above about twenty-one psi,whereby, on operation of said apparatus when the car body is under empty conditions, the load sensing member is shifted by said casing piston to move the load sensing member to its said extended relation, said lever device is actuated by said piston means to place said check valve assembly in its open relation, whereby the braking air is communicated from said casing first chamber to said casing second chamber and thence through said third pipe means to said modulating valve second chamber whereby said modulating valve member closes said modulating valve seat and the braking air at said partial braking pressure is communicated through said casing first chamber to said second pipe means and the brake cylinder for empty load brake operation of said apparatus.

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