Wednesday, August 17, 2011

THE TYPE H BRAKE VALVE

This valve has six operating positions which are, Release, Running, Holding, Lap, Service and Emergency.


RELEASE POSITION
Provides a direct passage from the main reservoir to the brake pipe that permits a rapid flow of air into the brake pipe, allowing for a quick release and recharging of the train brakes without releasing the engine and tender brakes.

RUNNING POSITION
This position releases the engine and tender brakes and also charges the brake pipe, releasing the train brakes.

HOLDING POSITION
This position is so named because the locomotive brakes are held applied as they are in the Release Position, while the train brakes feed up to the feed-valve pressure.

LAP POSITION
This position is used to hold the brakes after a Service application, either to make a further brake-pipe reduction, or to release the brakes. It also prevents the loss of main reservoir pressure in case of an event like a burst hose. LAP Position is also used on an engine in a train not controlling the train brakes.

SERVICE POSITION (automatic service)
This position gives a gradual reduction of brake-pipe air and allows it to flow to atmosphere. When the pressure is reduced to the desired amount, the handle is moved to the LAP position, stopping the discharge of brake-pipe air.

EMERGENCY POSITION.
This position is used when the fastest application of all brakes is needed.

The valve also contains ports to provide connections to gauges and governors.


This valve works in conjunction with other devices such as the Independent Brake Valve, the Distributing Valve, the Equalizing reservoir, the Pump Governor and various smaller valves such as the Feed Valve and the Reducing Valve.








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