The geometric angle between the plane of a rolling wheel and the longitudinal axis of the rail. In tight curves, a rigid truck cannot perfectly align its axles with the track radius, causing the leading outer wheel to steer into the rail at an angle. A high angle of attack increases friction, causes severe flange wear, and raises the risk of the wheel climbing the rail and derailing.
Heard on the job
The track inspector noted heavy gauge face wear on the curve, likely from the high angle of attack of the six-axle motors.