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40 FIGURE F-5 First 3 seconds for a pneumatic system after air hose separation 75 cars from the rear of a 150-car test rack. Car numbers refer to the car position trailing the POD. Car 1 is the first trailing car. BP = brake pipe; BC = brake cylinder. FIGURE F-6 Pneumatic system that experiences an air hose separation 75 cars from the rear of a 150-car test rack. Brakes are fully actuated after 16 seconds. Car numbers refer to the car position trailing the POD. Car 1 is the first trail- ing car. BP = brake pipe; BC = brake cylinder.
41 Figure F-7 shows performance when the POD is 40 cars from the rear of the train. The full BCP on the 40th car is reached 14 seconds after the air hose separation. Figure F-8 shows the emergency brake performance of a train for which the POD is 115 cars from the rear. The train does not use an EOT device or a DP configuration. Comparison of Figure F-8 with Figure F-9 (presented below) indicates that one of the benefits of an EOT device or a DP configuration is reduced time for full actuation of the brakes. Test Rack Data Representing a Train in Pneumatic Mode with EOT Brakes During an emergency brake application on a train with EOT brakes that is initiated by a separation of the air hoses, the drop in BPP travels toward both the head and the rear of the train at the same speed in a pneumatic wave through the BP. If the loss in BPP is first detected at the device at the end of the train, the device radios an emergency brake message to the HOT device, which then signals for emergency brake ap- plication from the front of the train. If BPP loss is first sensed at the lead locomotive, the HOT device sends an emergency brake application message to the end via radio link, and the device at the end of the train also initiates an emergency brake application from the rear. Therefore, EOT emergency brake applications are more effective when the POD is in the front half of the train. This effect is stronger the closer the derailment is to the front of the train. When the emergency braking is initiated in the rear half of the train (on the basis of BP length), EOT devices offer no brake signal propagation advantage over pneumatic brakes without EOT devices. Figure F-9 shows a derailment occurring on the first car of a 150-car train. The graph is applicable whether the train has an EOT device or rear DP. However, the response times do not include radio response times between devices. FIGURE F-7 Pneumatic system that experiences air hose separation 40 cars from the rear of a 150-car test rack. Brakes were fully actuated after 14 seconds. Car numbers refer to the car position trailing the POD. Car 1 is the first trailing car. BP = brake pipe; BC = brake cylinder.
