A. To control and maintain a constant pressure in the brake pipe when
the brake valve is in running or holding position.
103. Q. What defect in the feed valve will cause the brake pipe pressure
to equalize with that in the main reservoir?
A. This may be caused by a defective feed valve case gasket, permitting
main reservoir air to leak into the feed valve pipe, or leakage past the
supply valve, or the regulating valve held from its seat, or the supply
valve piston too tight a fit in its cylinder.
104. Q. If the brake pipe charges too slowly when nearing the maximum
pressure, where is the trouble?
A. This may be caused by a loose-fitting supply valve piston 8, or the
port past the regulating valve 12 partly stopped up.