Nadal formula
Encyclopedia
The Nadal formula, also called Nadal's formula, is an equation in railway design that relates the downward force exerted by a train
's wheels upon the rail, with the lateral force of the wheel's flange against the face of the rail. This relationship is significant in railway design, as a wheel-climb derailment may occur if the lateral and vertical forces are not properly considered.
The Nadal formula is represented by:
In this equation, L and V refer to the lateral and vertical forces acting upon the rail and wheel, δ is the angle made when the wheel flange is in contact with the rail face, and μ is the coefficient of friction between the wheel and the rail.
Typically, the axle load
for a railway vehicle should be such that the lateral forces of the wheel against the rail should not exceed 50% of the vertical down-force of the vehicle on the rail. Put another way, there should be twice as much downward force holding the wheel to the rail, as there is lateral force which will tend to cause the wheel to climb in turns. This ratio is accomplished by matching the wheelset with the appropriate rail profile
to achieve the L/V ratio desired. If the L/V ratio gets too high, the wheel flange will be pressing against the rail face, and during a turn this will cause the wheel to climb the face of the rail, potentially derailing the railcar.
Train
A train is a connected series of vehicles for rail transport that move along a track to transport cargo or passengers from one place to another place. The track usually consists of two rails, but might also be a monorail or maglev guideway.Propulsion for the train is provided by a separate...
's wheels upon the rail, with the lateral force of the wheel's flange against the face of the rail. This relationship is significant in railway design, as a wheel-climb derailment may occur if the lateral and vertical forces are not properly considered.
The Nadal formula is represented by:
In this equation, L and V refer to the lateral and vertical forces acting upon the rail and wheel, δ is the angle made when the wheel flange is in contact with the rail face, and μ is the coefficient of friction between the wheel and the rail.
Typically, the axle load
Axle load
The axle load of a wheeled vehicle is the total weight felt by the roadway for all wheels connected to a given axle. Viewed another way, it is the fraction of total vehicle weight resting on a given axle...
for a railway vehicle should be such that the lateral forces of the wheel against the rail should not exceed 50% of the vertical down-force of the vehicle on the rail. Put another way, there should be twice as much downward force holding the wheel to the rail, as there is lateral force which will tend to cause the wheel to climb in turns. This ratio is accomplished by matching the wheelset with the appropriate rail profile
Rail profile
The rail profile is the cross sectional shape of a railway rail, perpendicular to the length of the rail.In all but very early cast iron rails, a rail is hot rolled steel of a specific cross sectional profile designed for use as the fundamental component of railway track.Unlike some other uses of...
to achieve the L/V ratio desired. If the L/V ratio gets too high, the wheel flange will be pressing against the rail face, and during a turn this will cause the wheel to climb the face of the rail, potentially derailing the railcar.