Continual quick service valve device with fast charging means

Claim 1

A cycling-type continual quick service means for a vehicle fluid pressure brake control apparatus operative in response to variations in pressure iin a normally charged brake pipe, said quick service means comprising: a. a casing having formed therein a quick service chamber, b. a movable abutment supported by said casing and subject to the pressure in the brake pipe in a first chamber on one side thereof and to the pressure in the quick service chamber in a second chamber on the other side, said abutment being movable responsively to the preponderance of pressure in either chamber over that in the other, c. communication means via which to charge said first and second chambers and said quick service chamber from the brake pipe, d. a first valve means normally closing a communication between said first chamber and atmosphere and operative by said abutment to open said communication to vent said first chamber and thereby the brake pipe to atmosphere responsively to movement of said abutment in one direction as a result of an operator-initiated reduction of pressure in the brake pipe, e. a second valve means operatively connected to said abutment through a lost-motion connection and which opens said communication means to cause said quick service chamber and said second chamber to be charged from the brake pipe, said second valve means being operative by said abutment upon equalization of the pressures in said first and second chambers to cut off flow of fluid under pressure through said communication means to said second chamber and said quick service chamber, and being operative by said abutment, after said first valve means has opened said communication, to open a communication via which fluid under pressure is vented from said second chamber and said quick service chamber to atmosphere. f. first choke means restricting the venting of fluid under pressure from said second chamber and said quick service chamber to such a rate as to insure the venting of fluid under pressure from the brake pipe to atmosphere by said first valve means for a certain predetermined time before the reduction of pressure in said second chamber and said quick service chamber is sufficient to cause a reversal of direction of movement of said abutment whereby said abutment is effective, upon initial movement in the reversed direction, to cause operation of said first valve means to terminate further venting of fluid under pressure from the brake pipe and, upon further movement of said abutment in said reversed direction, is effective to operate said second valve means to terminate further venting of said second chamber and said quick service chamber, g. second choke means cooperating with said communicating means to control the rate of flow of fluid under pressure from both the brake pipe and said first chamber to said second chamber and said quick service chamber, and wherein the improvement comprises: h. means cooperating with said second choke means to enable the rate of supply of fluid under pressure to said second chamber and said quick service chamber to exceed the rate fo flow of flud under pressure therefrom.