1920


	1920	Mack pioneers the use of power brakes on trucks by using a vacuum-booster system. Mack was the first to introduce the use of rubber isolators as cushions in mounting chassis components to improve shock resistance in 1921. The applicability of this technology to automobiles was so great that the Rubber Shock Insulator Company was formed to handle license agreements with other automobile firms. New Zealand Loan and Mercantile Agency - a forerunner of the today's ANZ bank - is appointed Mack's sole Australian distributor.
	1922	The title of the parent company is changed from International Motor Truck Corporation to Mack Trucks, Incorporated. This change in title was made to identify the corporate name more closely with the company's product and lessen any misidentification of Mack products with those of a competitor, the International Harvester Company. The International Motor Company continues as the manufacturing subsidiary of Mack Trucks, Inc. until 1936. In 1922, the company adopted the Bulldog as its corporate symbol. The first usage of the Bulldog as a symbol was on a sheet metal plate riveted to each side of the cab. It was first drawn on June 3, 1921 and was released, printed, and specified for the AB chain drive (CD) and dual reduction (DR) carrier drive trucks. The plate shows the Bulldog as two words, i.e., a bull dog chewing up a book entitled "Hauling Costs," "Mack" on his collar, and International Motor Co. of New York. This plate was used much later on M model off-highway trucks, except that the plate then showed Mack Trucks, Inc., Allentown, PA.
	1924	In the early afternoon of March 14, Jack Mack was enroute to a business meeting in Weatherly, Pennsylvania in his Chandler coupe. His car became involved in an accident with a trolley car of the Lehigh Valley Transit Company, which was crossing the road diagonally. Jack was killed almost instantly when his light car, being pushed off the road ahead of the trolley, was caught against a heavy pole and crushed like an egg shell. His body was interred in Fairview Cemetery in Allentown, just above the former Mack plant on 10th Street.
	1927	Over the years there have been few Mack models as famous as the AC model. The Mack BJ and BB models, the first of the "early B Series" introduced in 1927, represented the company's first trucks developed in response to the demand for larger capacity, higher speed haulage. The growing acceptance of trucking as a transport mode required the application of new design and engineering principles, and a variation of sizes and weights to satisfy emerging state regulations. More than 15,000 units were built through 1941.
	1929 - 1944	During the years from 1929 until 1944, Mack produced 2,601 semi- or full trailers. Full trailers were of two styles, non-reversible or reversible. Non-reversible trailers had a solidly fastened rear axle arrangement with a draw bar on the front end so that the trailer could be drawn in one direction. A reversible trailer has axle arrangements similar at each end. Either end could be fastened in a stationary position while the draw bar could be fastened to the other end of the trailer. In this way, either end could be the front of the unit.
	1932	Early in 1932, Alfred Fellows Masury, Mack's Chief Engineer, was admitted to the hospital for an operation. Masury was one of those individuals who wasn't used to his hands being idle for any period of time. During his recuperation in the hospital, Masury decided to carve a bulldog. (Some rumors indicate that he carved the first bulldog from a bar of soap; other rumors indicate the first was carved from wood.) Whether the first bulldog hood ornament was soap or wood, we do know that shortly after his release from the hospital, he did in fact carve a bulldog in wood. Masury applied for and received a patent for his design; that Bulldog design has adorned Mack trucks ever since!
	1933	A year of growth and building in America, and Mack Trucks, Inc. played a major role, including the building of Boulder Dam!
	1936	The name of the International Motor Company is changed to the Mack Manufacturing Corporation. The Mack E series, introduced in 1936, were streamlined, medium-duty trucks with gross vehicle weight ratings ranging up to 23,000 lbs. The E models were available in both conventional and cab-over-engine configurations and proved themselves among the most versatile products ever offered by Mack. Over 78,000 were produced through 1951. Mack was one of the first truck manufacturers to apply four-wheel brakes to heavy-duty trucks, increasing braking ability and safety, particularly with heavier loads. In 1938, Mack became the first truck manufacturer to design and build its own heavy-duty diesel engines, establishing the tradition of "balanced design" (in which the integration of the powertrain and vehicle design maximize performance) that continues today. Mack was a major military contractor on a much larger scale in World War II, with more specialized products. Mack trucks served the Allied forces 35,000 strong in that second conflict, in the form of prime movers, personnel carriers, wrecker trucks, tank transporters, and more.
	1936 - 1938	Mack merchandised a series of trucks under the name "Mack Jr." The vehicle was actually built by the Reo Truck Company in Lansing, Michigan. The vehicles were built according to Mack specifications and were sold through the Mack sales organization. In total, there were 4,974 chassis built during this time frame. This was the second time in its history that Mack sold a Mack junior chassis. The 1936-1938 units should not be confused with the earlier Mack Junior; production on that version began in 1909. During the 1938 to 1944 period, Mack built and sold a model called the "ED," which was essentially a three-quarter ton vehicle. Records indicate that a total of 2,686 ED model trucks were delivered.
	1936 - 1972	Mack built off-highway or mine trucks from 1926 to 1972, from 15 to 100 ton capacity. The Mack AP model was Mack's first off-highway vehicle. From 1926 through 1938, 285 of this units were built. From 1943 through 1964, a total of 1,275 of the LR model truck was built. The next generation, the LV model, was built from 1948 through 1961; 515 of these units were built and sold. The M Series, rated from 15 to 100 tons, was produced from 1960 to 1979.
	1940 - 1953	Mack produced marine engines for many years. "The Mariner" engines were used in yachts, pilot and work boats. The ENDM 405 (FW) was produced from 1940-1941; a total of 16 engines were manufactured.