应用指南

PROBLEM:

Federal regulations mandate the use of aviation style "black boxes" or event recorders on railroad trains. If an accident occurs, the time-referenced event recorder supplies information essential in determining the cause of the accident. The event recorder receives data from a variety of sensors, including pressure transducers, which monitor the train's pneumatic brake system. When the brake air-lines are pressurized the brakes are inactive; if braking is required, pressure is released and the high-torque brakes engauge. Because the brake air-lines are connected from car to car in series, a leak in one air-line will affect all the cars in the train. To minimize the possibility of leaks the designers rejected transducers with internal O-ring seals.

The event recorder design specifies a set of two transducers, one for the measurement of brake cylinder pressure (120 psi) and one for the air supply header (160 psi). Additional design requirements include integral transducer mounting brackets and a detachable water-resistant electrical connector.

SOLUTION:

Honeywell Sensing and Control worked closely with the customer to develop a transducer that meets all of the design requirements. Based on the model SA, the transducers are calibrated to the specified ranges, fitted with mounting brackets, and a DIN-approved electrical connector. The integrity of SA's brazed one-piece construction substantially reduces the possibility of transducer-related leaks.

ENVIRONMENT:

The transducers are mounted to a panel in the engine cab where temperatures vary from 50°F to 90°F. Vibration levels are moderate. The air supply is dirty; the ends of the brake air-lines are open when the cars are separated from one another, so windblown dust and debris can enter. SA's rugged construction resists damage from these contaminants.

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