Shore durometer The basic test requires applying the force in a consistent manner, without shock, and measuring the hardness (depth of the indentation). If a timed hardness is desired, force is applied for the required time and then read. The material under test should be a minimum of 6 mm (0.25 inches) thick. The ASTM D2240 standard recognizes twelve different durometer scales using combinations of specific spring forces and indentor configurations. These scales are properly referred to as durometer types; i.e., a durometer type is specifically designed to determine a specific scale, and the scale does not exist separately from the durometer.
Chicago North Shore and Milwaukee Railroad 1979. The outbreak of World War II caused the railroads of the United States to see a sharp rise in traffic. Even before the imposition of rationing of fuel and rubber made auto travel difficult, the North Shore saw its freight and passenger traffic rise to record levels, in part due to the railroad serving important military facilities: the Army's Fort Sheridan just north of Highwood, and the Navy's Great Lakes Naval Training Station, just south of North Chicago. North Shore saw its traffic increase to the extent that the railroad was forced to borrow equipment from the Chicago Rapid