The automatic brake valve controls the train brakes, and its quadrant has six positions:

Release, Minimum Reduction, Service, Suppression, Handle Off and Emergency.

This is the black handle in the photos below.

(1)Release: Located to the extreme left of the quadrant, is used for charging the air brake system and to release an automatic brake application. This is the normal running position.

(2)Minimum Reduction: Located against the first raised portion to the right of Release, is used to obtain a service brake pipe reduction of 6 to 8 psi. This is also called First Service.


(3)Service: Extends to the right of Minimum Reduction on the quadrant to just short of the second raised portion. The farther the handle is moved in the Service Zone the greater will be the reduction. The independent brake also applies as a larger reduction is made here.

(4) Suppression (not shown): is against the second raised portion and is used to recover penalty application.


(5)Handle Off: Located under the opening which permits removal of the handle. In this position, brake pipe pressure can be reduced to zero at a service rate.


(6)Emergency: Located at the extreme right of the quadrant is used for making an emergency brake application, whether brake valve is cut in or out.

The independent brake valve controls the engine's brakes, and has two positions:

Release and Apply

The automatic brake is not affected by the application or release of this brake.

(1)Release: Located to the extreme left, is used to release an engine brake application. An application of the automatic brake also causes the independent to be applied. If the engineer desires to release his engine brakes at this time while keeping the train brakes applied, he presses down on the independent lever. This is called "bailing" the independent, and keeps the engine stretched out from the train.


(2)Apply: Located to the extreme right, is used to make a maximum engine brake application, usually during a stop. Positions between Release and Apply provide a continuously variable amount of application.