Hydraulic Torque Converter CROM the outset of the use of the hydraulic torque • converter in excavators, tractors, earthmoving machinery and off-highway trucks, it was generally conceded that the converter would help start heavy loads smoothly, reduce shock and torsional loads, and eliminate stalled and lugging engines due to overloads. This understanding and reduction of operator effort led to the wide acceptance of the converter drive by the earthmoving industry, and ore and coal mine operators all over the country. At the same time it was indicated that the con-verter drive was contributing directly to longer engine, transmission and differential life by the elimination of shock loads which many operators claim were responsible for a great percentage of the transmission, driveline, and rear axle failures. Hand-in-hand with speculative converter char- acteristics and reports of longer life for its power- train components, Allison began to accumulate a wide experience in building many different models of hydraulic transmissions for both commercial and military applications. After one of the first MANY recent design improvements in hy- draulic transmissions have followed the trend toward longer life of power-train components established by the use of a torque converter. The need for actual data relating to the charac- teristics of torque-converter operations led to the series of field tests reported in this paper. Off-highway trucks used in earthmoving, coal, and ore hauling were made available for the tests, together with experienced operators. Mea- surements of driveline stresses were recorded for trucks equipped with converter drives, and for those having mechanical transmissions. Comparisons indicated that, with a converter, equipment can be operated at a higher load fac-tor in order to get more work done, and also that the equipment will have a greater life fac- tor. These two factors will result, of course, in reduced operating costs to the user. The Authors R. M. SCHAEFER (M '29) is manager, Transmission En- gineering Department, Allison Division, CMC. He is in charge of both commercial and ordnance transmission pro- grams. Mr. Schaefer received his mechanical engineering degree from the University of Munich. |. A. WINTER is senior project engineer, Research and Development Section, Transmission Engineering Depart- ment, Allison Division, CMC. He joined General Motors in 1934. Before obtaining his present position he was assigned to the General Motors Aircraft Development Sec- tion as development engineer. 142 SAE TransactionsDownloaded from SAE International by University of Birmingham, Sunday, September 30, 2018Its Effect on the Power Train R. M. Schaefer and J. A. Winter, Allison Division, GMC This paper was presented at the SAE National Tractor Meeting, Milwaukee, Sept. 9, 1952. hydraulic torque converter transmissions had been in service for several years with good results, it was felt that the capacity of this transmission could be increased. The present rating permits its use in connection with 50% larger engines without experiencing any difficulties such as shorter life and increased failures due to excessive stresses. This experience indicated that the normal load and stresses on the parts of hydraulic transmis- sions could be increased over the values previously used due to the use of the converter in the power train. Even with operator's records indicating a trend towards longer life of power-train components when using a torque converter, and our design and field experience in hydraulic transmissions, there was still felt by everybody directly concerned with the use of transmissions, the need for actual data relating to the characteristics of torque converter operation. With this interest established as a subject for 'the 1952 SAE National Tractor Meeting in Milwau- kee, the impetus necessary was provided to develop and carry through a series of actual field tests. In consideration of the accessibility of th