Continual quick service valve device

Claim 1

In a fluid pressure brake equipment, the combination of a brake pipe normally charged with fluid to a certain chosen pressure and a continual quick service valve device comprising: (a) a control volume, (b) choke means for controlling the rate of flow of fluid under pressure from the brake pipe to said control volume whereby said control volume is charged with fluid under pressure from the brake pipe to the same pressure as that in the brake pipe, (c) a quick service volume, (d) a pair of fluid pressure operated valve means arranged in series for controlling flow of fluid under pressure from the brake pipe to said quick service volume, the first of said fluid-pressure-operated valve means being so arranged and constructed as to, when in a first position, enable flow of fluid under pressure from both said control volume and said quick service volume to atmosphere while cutting off flow from the brake pipe to said quick service volume and, when in a second position, enable flow of fluid under pressure from the brake pipe to the quick service volume while cutting off flow from both said control volume and said quick service volume to atmosphere, and the second of said fluid-pressure-operated valve means constituting a spring-biased valve for enabling flow from both the brake pipe and said control volume to said quick service volume while said first valve means is in its said second position, (e) three choke means so arranged in series as to enable flow of fluid under pressure therethrough from said control volume to atmosphere while said first valve means is in its said first position, the first of said choke means being of such size as to enable the flow of fluid under pressure therethrough at a service rate of reduction of brake pipe pressure and so arranged as to, in cooperation with the second of said choke means, establish a differential fluid pressure to cause said first fluid-pressure-operated valve means to operate from its first position to its second position, and the third of said choke means being of a size greater than the size of said second choke means and so arranged as to release fluid under pressure from said quick service volume to atmosphere while said first fluid-pressure-operated valve means is in its said first position independently of said first and second choke means, and (f) a third fluid-pressure-operated valve means for controlling flow of fluid under pressure from said control volume to the first of said choke means, said third fluid-pressure-operated valve means comprising: (i) a biasing means, (ii) a valve seat, and (iii) a movable abutment so arranged as to constitute a valve movable into and out of seating engagement with said valve seat, said abutment being subject on the side thereof adjacent said valve seat to the pressure in said control volume and on its other side to said biasing means and also the pressure of the fluid in the brake pipe so that a reduction of pressure in the brake pipe enables the fluid under pressure in the control volume to unseat said abutment from said valve seat whereby so long as said abutment is unseated from said valve seat, fluid under pressure flows from said control volume through said first and second choke means to establish said differential fluid pressure thereby enabling successive sequential operation of said pair of fluid-pressure-operated valve means to release fluid under pressure from the brake pipe to said quick service volume and thereafter release the fluid under pressure in said quick service volume to atmosphere.