Experimental Devices for the Investigation of Sliding Friction

摘要

Two machines were constructed for studying sliding friction at low and high velocities. One of the machines was used for studying friction for sliding velocities ranging from 0.005 to 0.35 mm/min, and the second for studying sliding velocities from 2 to 2800 mm/min. The hydraulic and mechanical components of the equipment are shown in schematic diagrams. The machine for studying friction at low slip velocities consisted of a slide bar positioned between two loading members for applying normal loads to the bar. Motion was imparted to the slide bar by a piston operating under oil pressure. The specific pressure acting normal to the slide bar could be regulated. Friction forces were recorded as a function of time by means of a strain gage (glued to the upper plate) and an oscillograph. For changes in slip velocity from 0.005 to 0.35 mm/min the friction force remained constant, other things being equal, and sometimes even increased somewhat. A sharp increase or decrease in friction force during the motion of the slide bar did not occur for all ranges of velocity, with or without lubricant. The differences between static and dynamic friction were negligible. The apparatus for studying friction at slip velocities up to 2800 mm/min is also described. Strain gages were used to measure the friction force. Studies were conducted on cast iron-cast iron, steel-cast iron, steel-steel, and other types of surfaces. (Author)