This aluminum wheel profile gauge is used to measure a railcar's wheels to ensure they are safe. The gauge is used to determine if the wheel is flat, thin in the flange area, or has wear between the flange and the flat section of the tread. Use the wheel profile as your first step in diagnosing "hunting" on the rails.
Use two of the wheel profile gauges to determine the track gauge of the car (ie, space between the two front or two rear wheels). This new version has a slot for a tape measure when measuring the width between the wheels. The width at this measurement should be 56 and 1/4 inches. This is the recommended width between the inside of the wheel flanges on each side of the car. The Standard US Rail Gauge (4 feet 8 and 1/2 inches) is 56 and 1/2 inches. The smaller size allows the flanges to fit inside the rail gauge.