Special Coupler-Pin Development for Measuring Railroad-Locomotive Drawbar Forces

摘要

A new method has been developed for measuring the drawbar dynamic forces exerted by a railroad locomotive while pullings its payload. Such data are necessary to determine the effect of train handling on fuel economy and on locomotive performance. Previous methods modified the bulky locomotive coupler for use as the force-sensor. This resulted in expensive devices which were difficult to transport because of their bulk and which had strain-gage exposures vulnerable to damage in the severe environment of railroad operations. The new method uses a specially-designed coupler pin as the force-sensor. In this special pin, the shear-forces (imposed by the locomotive drawbar) are first transformed into bending stresses and then measured by strain-gages located inside small longitudinal holes in the shear pin. This results in important advantages over the previous methods; the new sensor is much less expensive, more easily portable (30 vs. 400 pounds) and more reliable and less susceptible to damage. A prototype pin has been built and successfully tested in the laboratory at full operating load and the load resolution has met design specifications. This paper describes the design, construction, and testing of the pin.