Inshot valve arrangement for railway brake control apparatus employing combined air reservoir/brake cylinder device

An inshot valve device comprising:

• (a) first valve means having an open and a closed position for conducting and interrupting, respectively, the venting of brake control fluid pressure in response to which venting a brake application is established;
• (b) a control piston having first and second positions in which said control piston is engageable with said first valve means to control operation thereof to said open and closed positions, respectively, said control piston having opposing pressure chambers formed on the respective sides thereof subject to said brake control pressure, said brake control pressure of one of said opposing chambers acting on a first pressure area of said control piston and said brake control pressure of the other of said opposing chambers acting on a second pressure area of said control piston;
• (c) means for biasing said control piston in said first position, in which position said brake control pressure in said one of said opposing chambers is trapped during an emergency brake application, so that said venting of said brake control pressure during said emergency application establishes a pressure differential across said control piston to overcome said bias and force said control piston to said second position;
• and
• (d) said control piston further having a third pressure area on the same side thereof as said first pressure area, such that said first and third pressure areas combined are a predetermined percentage greater than said second pressure area, said third pressure area being defined by a vented pressure chamber, said control piston further including second valve means operative in said second position of said control piston for connecting said trapped brake control pressure to said vented pressure chamber so as to be effective on said first and third pressure areas of said control piston and thereby prevent said control piston from resetting to said first position for a predetermined duration.