Opinion holds that the line of demarkation between low speed and high speed operation, from the coach design point of view, is in the region of 80 to 85 mph. Bogies that have been tested in freight wagons have exhibited good riding qualities at 80 mph, or lower, but have shown themselves entirely unsuited to speeds above 85 mph, in some of the tests the shocks recorded were doubled in intensity as speed increased from 80 to 90 mph. Up to 80 mph the amplitudes of body swing were within reasonable limits, but at 90 mph the body of the box wagon under test was becoming unstable. Experiments proved that, given equal conditions of springing and of maintenance, a six-wheel bogie gives slightly better riding in both vertical and horizontal planes than a four-wheel bogie, and has better braking qualities also; but the gain is not considered to be worth the increase in weight, first cost, and cost of maintenance. In the design of passenger-car bogies, coil bolster springs perform the same duty as the swing hangers in the elliptic spring bogie. Another important requirement is that in wheels for high speed equipment the treads shall be concentric within 0-10 in. Experiment showed that one of the principal factors in causing bogies to "hunt" at speed, is a short and sharp taper close to the throat of the main flange of the wheels, even if the extent of the taper be no more than 1/10 in. No bogie design tried by the Milwaukee has given good riding at high speed if the wheels have been in this condition, and the only way to restore such wheels to good riding qualities is by re-turning or griding them.

  • Corporate Authors:

    Temple Press Limited

    161-166 Fleet Street
    Longon EC4,   England 
  • Publication Date: 1945-4-6

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  • Accession Number: 00037286
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 8 1994 12:00AM