Locomotive wheel failure from gauge widening/condemning: Effect of wheel profile, brake block type, and braking conditions

• Effect of wheel profile, brake blocks and braking types on gauge change is studied.
• Gauge reduction during braking is seen to be a serious problem that is overlooked.
• S-shaped wheels are most effective for avoiding excessive gauge change.
• Straight plate locomotive wheels result in largest gauge increase for stop braking.
• All loco wheel profiles fail for independent braking with high friction brake pads.

A finite element model accounting for heat partitioning at brake block–wheel and rail–wheel interfaces is used to investigate the effect of locomotive wheel profile, wheel diameter, brake block type, nature of braking (independent, synchronized, and drag), braking frequency and braking cycles on wheel gauge for tread braked, locomotive wheel sets. A train running model estimates heat generation rates during braking for assumed operating and braking conditions. Wheel profiles and brake block types used in the work, match with that used by Indian Railways. Bending at hub–disc and disc–rim interfaces is seen to primarily control axial deflection of wheels. While gauge reduction is observed during braking, gauge increase is seen during subsequent cooling. Maximum gauge increase occurs as the wheels finally cool down to room temperature. S-shaped wheels are seen to be better suited than straight plate and parabolic profile wheels for avoiding excessive gauge change. Locomotive wheel failure from gauge widening and condemning, albeit at different times, is seen to occur with independent braking for locomotives fitted with straight plate, S-shaped as well as parabolic profile wheels.