LIBRARX SOCIETY OF AUTOMOTIVE ENGINEERS, INC. 485 Lexington Avenue, New York, N. Y. 10017 The Evolution of Power Trains and Steering in High Speed Military Track Laying Vehicles Edward Hamparian U. S. Army Tank-Automotive Command SOCIETY OF AUTOMOTIVE ENGINEERS Farm, Construction and Industrial Machinery Meeting Milwaukee, Wis. September 11-14, 1967 670726 Downloaded from SAE International by Imperial College London, Sunday, September 09, 2018670726 The Evolution of Power Trains and Steering in High Speed Military Track Laying Vehicles Edward Hamparian U. S. Army Tank-Automotive Command THIS PAPER presents information regarding the evolution of transmission and power train development, design, design objectives, and criteria necessary for application in high speed military tracklaying vehicles. Included are analyses of major systems since World War II with investigations and trends for future consideration. The high performance of this country's new series tanks, cargo carriers, and other tracklaying military vehicles now in production is the result of long range planning and de­ velopment started before the end of World War II. Under the direction of the Army Tank-Automotive Command, in­ dustry was asked to design improved transmissions and power trains as part of a new components development program to match the new vehicle developments. It was desired to shape the new hulls around the smallest practicable power package of engine, cooling system, trans­ mission, and steering-brake systems. By including in the ABSTRACT This paper discusses the historical development of the transmission and power train in high speed military track- laying vehicles. It is apparent that the final design of any power train system for military vehicle application must take into consideration factors such as vehicle performance criteria, vehicle weight class and influence, engine appli­ cation, and mission profile. Detailed analyses of various power train systems, such as the X-700, XHM-1500, and HMPT-100, are presented. The basic aim was to shape the new hulls around the smallest transmission unit the steering and braking, and by molding this unit for a vehicle series into an outline arrangement to best match the appropriate engines, much hull space could be saved. The space saved could be used to permit the in­ stallation of more powerful engines in the same hull sizes, or could enable smaller, lighter vehicles to be designed, or could provide for increased room in the crew department. In other words, vehicle power-weight ratios could be im­ proved without sacrifice of other important military char­ acteristics. TANKS NEEDS DEMONSTRATED It was required that full use be made of prior evolutionary developments in tank transmissions. Torque converters with full-torque shifting gear changes were an already proved re­ quirement for best performance and handling. Also World practicable power package of engine cooling system, trans­ mission, and steering-brake system. By including the steer­ ing and braking in the transmission unit much hull space could be saved, and the space saved could be used for in­ stallation of more powerful engines. Based upon a vast background of knowledge developed since World War II, ATAC is maintaining a very high level of effort in assuring that the latest and most advanced drive systems are available for the United States military combat vehicle. Downloaded from SAE International by Imperial College London, Sunday, September 09, 20182 War II demonstrated the need for a tank of greater agility and mobility, simplified operation, and reduced maintenance. Could this be accomplished using the power train com­ ponents as they existed in 1943 in the M -4 medium tank ? These components consisted of engine, clutch, transmission, steer differential, and brakes. These components were carried over from commercial truck and tractor use and upgraded for power requirement