EFFECT OF THROW OR RUN-OUT OF AXLES

The objective of the program was to determine the dynamic augment (or centrifugal force) in axles having throw from 1/4-in. to 1/2-in. Twenty-one freight axles were obtained for this investigation, twelve of which are of the present standard design having black collars, and the other nine are of a proposed design, identical to passenger car axles except as-forged between the raised wheel seats. The procedure used to obtain data on throw and unbalance was to mount each axle in a balancing machine, rotate the axle at 360 rpm and counterbalance each end, and then obtain ten equally-spaced dial gage readings of the axle surfare at each of three locations along the length of the axle. It was found that two-thirds of the axles tested have throw of 1/4-in. or less; the remainder have throw not exceeding 3/8-in. Where throw is significant it is a satisfactory indication of eccentricity. Dynamic augment or centrifugal force varies within a range of plus minus 100% from the average for a given value of throw. Values of dynamic augment were found, at 100 mph, from 57 to 1346 lb. Unbalance of 1.6 ft.-lb., average, is caused by each 1/8-in. of throw. A change in the allowable limit of throw from 1/4-in. to 3/8-in. would have no appreciable effect on lading damage.

• Supplemental Notes:
  • Summary page of report only.
• Corporate Authors:

  Association of American Railroads

  50 F Street, NW
  Washington, DC  United States  20001-1564
• Publication Date: 1952-1

Media Info

• Pagination: 1 p.

Subject/Index Terms

• TRT Terms: Axles; Centrifugal force; Freight cars; Loading and unloading; Loads; Railroad cars; Technology; Vehicle design
• Geographic Terms: United States
• Old TRIS Terms: Axle design; Unbalanced loading
• Subject Areas: Design; Railroads;

Filing Info

• Accession Number: 00040243
• Record Type: Publication
• Report/Paper Numbers: AAR MR-117
• Files: TRIS
• Created Date: Jul 8 1994 12:00AM