Characterizing the Performance of Cast-Iron, High-Phosphorus Cast-Iron, and Composition Freight Car Brake Shoes under Simulated Drag Braking Conditions

摘要

The performance of the cast-iron, high-phosphorus cast-iron, and composition brake shoes was evaluated through a test program under conditions simulating the operation of a loaded 70-ton freight car on a long downgrade or 'stuck brake' situation. The major part of the test program dealt with brake tests at constant speeds of 20, 30, and 40 mph with about 30 bhp energy-dissipation rate. Additional tests included simulating 'worst-usage cases' and those conducted to determine the effects of a rolling-contact load, partial shoe contact, and brake-shoe force magnitude on the performance of three types of shoes. During each test, the braking torque, the wheel temperature, and the strain in the wheel were measured.