RECENT MEASURING OF THE RESISTANCE TO FORWARD MOTION OF ROLLING STOCK

The experimental measuring of the resistance to forward motion of rolling stock actually running on the track has always been difficult and the results obtained are subject to error. When carrying out research on the operation of trains at high speeds, the SNCF succeeded in devising a more general method which gives reasonably accurate results when measuring the mechanical and aerodynamic forces affecting resistance to forward motion. The authors explain the principles of the testing methods employed, the results obtained with various conventional types of rolling stock before arriving at a formula valid for hauled or mechanically propelled trainsets. This formula, which assumes that the wind force is nil, takes account of the vehicles' main geometrical dimensions.