Pneumatic/electro-pneumatic brake control system with interlock circuitry for push/pull train operation

In a train arranged for dual station control, a combined pneumatic and electro/pneumatic brake control system comprising:

• (a) a brake pipe extending through said train, the variation of pressure in said brake pipe controlling the brakes on said train;
• (b) an equalizing reservoir at each control station;
• (c) a brake valve device at each control station comprising:
• (i) an operating handle movable from a brake release position to a brake application zone, in which said equalizing reservoir at the same control station as said brake valve is charged with fluid pressure according to the position of said handle in said brake application zone;
• (ii) relay valve means subject to the fluid pressure effective at said equalizing reservoir at the same control station as said brake valve for controlling the fluid pressure in said brake pipe;
• and
• (d) a master controller device at each control station subject opposingly to the pressures in said brake pipe and said equalizing reservoir at the same control station as said master controller, and having application and release switches each open in the absence of a pressure differential between said brake pipe and equalizing reservoirs, one or the other of said switches being closed when a pressure differential arises between said brake pipe and equalizing reservoir depending upon the sense of said pressure differential;
• (e) a brake application wire extending through said train and energized by closure of said application switch to provide electrical control of said brake pipe pressure so as to effect variation thereof in a first sense;
• (f) a brake release wire extending through said train and energized by closure of said release switch to provide electrical control of said brake pipe pressure so as to effect variation thereof in a sense opposite said first sense;
• (g) a source of electric power;
• (h) interlock circuitry at each said control station, one of said control stations having said source of power connected thereto, said interlock circuitry comprising:
• (i) pressure switch means for connecting power from said interlock circuitry at said one control station to said master controller switches thereat when said brake valve at said one control station is activated and for energizing said brake application wire in bypass of said master controller application switch only when said brake valve at said one control station is deactivated;
• and
• (ii) means for deenergizing said brake application wire responsive to energization of said brake release wire.