making an emergency
application of the brake?

A. The valve should be placed in full emergency position and left there
until the train stops, even though the danger may have disappeared.

DEFECTS OF THE BRAKE VALVE

92. Q. What will cause a constant blow at the brake pipe exhaust port,
and what may be done to overcome it?

A. This indicates that the brake pipe exhaust valve is being held off
its seat, due no doubt to dirt; tapping the side of the valve will
sometimes stop the blow; if not, close the brake pipe cut-out cock and
make a heavy service reduction; next, place the brake valve handle in
release position. This will cause a strong blow at the exhaust port,
which will invariably remove the trouble.

93. Q. If the pipe connecting the brake valve with the equalizing
reservoir breaks, can both locomotive and train brakes be operated with
the automatic brake valve?

A. Yes; by placing a blind gasket in the pipe connection at the brake
valve and plugging the brake pipe exhaust port. To apply the brake, move
the handle carefully toward emergency position, making a gradual
reduction of brake pipe pressure through the direct exhaust ports of
the brake valve; when the desired reduction is made, the handle should
be moved gradually back to lap position.

94. Q. What would be the effect if the handle were moved to lap quickly?

A. Would cause the release of the brakes on the head end of the train.

95. Q. What will cause air to blow at the brake pipe exhaust port when
the handle is moved to lap position?

A. This is caused by a leak from the equalizing reservoir or its
connections, which reduces the pressure in chamber "D" above the
equalizing piston, allowing brake pipe pressure under the piston to
force it up, unseating the brake pipe exhaust valve, permitting brake
pipe air to flow to the atmosphere.

96. Q. What is the purpose of the equalizing reservoir?

A. The purpose of the equalizing reservoir is to furnish a larger volume
of air above the equalizing piston than is found in chamber "D", thus to
enable the engineer to make a graduated reduction of the pressure above
the equalizing piston.

97. Q. What defect will cause the brake pipe and main reservoir pressure
to equalize when the handle is in running position?

A. This may be caused by leakage past the rotary valve, defective body
gasket, or leakage by the feed valve or its case gasket. To determine
which part is at fault, close the cut-out cock