89 



The tests were made ou a 300,000-pound Riehle testing machine, a general 

 view of which, with the axle in place for testing, is shown by Fig. 1. Fig. 2 

 gives the dimensions of the axle and the details of the arrangements for applying 

 loads. The axle was supported by cast iron blocks, AA, four inches in breadth, 

 shaped to the form of a bearing, and extending from the center to the outer end 

 of the joumial. The actual points of supj)ort were located in the center of these 

 blocks. Load was applied to the wheel treads through steel rollers, BB, which, 

 at the beginning of the test, were located 4 feet 10 inches apart ; that is, at a point 

 corresponding to a position three-fourths of an inch outside of the inner or 

 "gauge face" of the rail upon which it may be supposed the wheels were set to 

 run. In this manner stresses were imposed upon the axle which were in every 

 way similar to those which might have been imposed by a car, if the axle had 

 been in service, but to give greater facility in testing, the usual order was re- 

 versed, the rails being assumed to be above the axle and the car below. 



Fig. 2 shows also the means employed in determining the deflections corre- 

 sponding to different loads. At each end of the axle there was attached a ligbt 

 arm (bb), extending at right angles both to the axle and to the plane of the stresses 

 to which it was subjected. Over these was stretched a fine wire parallel to the 

 axis of the axle. The wire passed through the web of the wheels, in holes which 

 were drilled for the purpose, and made sufficiently large to give ample clearance. 

 The whole length of wire between the arms (bb) was at all times perfectly free, 

 and the arrangement was such that although the axle might be bent by loads 

 applied to it, the wire would remain straight. Three micrometers attached to 

 blocks clamped about the axle served to locate the latter with reference to the 

 wire, and thus to determine the deflection. A fourth micrometer was used to 

 measure distances between the wheels' flanges in a line parallel with the axle and 

 16.J inches distant from its center. 



Loads were applied at C in 5,000 pound increments, and all micrometers 

 were read before each change of load. In this way a maximum load of 85,000 

 pounds was applied, under which the axle showed unmistakable signs of failure, 

 the elastic limit having been reached with a load of 55,000 pounds. The results 

 are presented graphically by Fig. 3, in which the curve marked "center" repre- 

 sents the deflections of the center of the axle as determined by the middle microm- 

 eter, Fig. 2; the curves marked "right" and "left" represent corresponding 

 deflections for points 18 inches either side of the center. Deflections of the axle 

 involved changes in the gauge of the wheels as measured above or below the axle, 

 the extent of which is indicated bv Fig. i. 



