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AMERICAN ARCH COMPANY

30 Church Street, New York McCormick Building, Chicago

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PLATE 85-No. 3-E CONTROL VALVE, P-C PASSENGER

Over Reduction Position

(Diagrammatic View)

CAR BRAKE EQUIPMENT

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ISOLATED PORTS

AND CHAMBERS

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SERVICE RESERVOIR

SERVICE CYLINDER

ATMOSPHERIC

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COLLEGE

CAMBRIDGE, MASS

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PUBLISHED MONTHLY BY THE BROTHERHOOD OF LOCOMOTIVE FIREMEN AND ENGINEMEN

COPYRIGHT, 1914, BY JOHN F. MCNAMEE

Entered as Second-Class Matter January 21, 1914, at the Post Office at Columbus, Ohio,
under the Act of Congress of March 3, 1879.

VOL. 57 No. 1

1

COLUMBUS, OHIO,

Plate 85-No. 3-E Control Valve, P-C Passenger Car Brake Equipment (Diagrammatic View)-Over

Reduction Position.

JULY 1914

reduction of its motive force-the pressure-chamber air-equally with the rethere comes a time when the pressureduction of the brake-pipe pressure; but

chamber air can reduce no more in this Plate 85 of the Westinghouse Air position-when the application chamber Brake Series of the Locomotive Firemen that receives the air contains as much as and Enginemen's Magazine Educational the pressure chamber has to give it after Charts represents the No. 3-E CONTROL VALVE of the P-C Passenger Car Brake Equipment in the usual sectional view and arranged diagrammatically, with the operative parts in the OVER REDUCTION POSITION.

If the brake-pipe pressure should be reduced low enough-even at the service rate of discharge-it results (in the P-C equipment) in emergency application, the emergency brake cylinder going into action full on. Over Reduction Position represents the state of the Control Valve during such an extended reduction, but in the margin of time after full service application is complete and before the emergency brake applies.

The equalizing piston in the Control Valve only moves through a part of its full traverse at service application; being checked at service position by its graduating spring, and more essentially by the

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which, the brake-pipe reduction continuing, the pressure-chamber air would immediately become enough greater than the brake-pipe pressure to force the "release piston" to its full traverse with the result of the application of the emergency brake cylinder-except for the limited restriction that takes place in the present position; as it is desired to delay this "service-emergency" action over a sufficient margin of brake-pipe pressure reduction, another chamber is provided (the "over-reduction chamber") into which the pressure-chamber air will begin to feed when the equalizing piston and its attached valves have reached their full limit of application traverse-and this begins a second phase of pressure-chamber depletion, which is simply to keep it from holding up a pressure much greater than that of the reducing brake-pipe; the air received by the reduction-limiting (1)

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