DESIGNERS of excavating machinery such as shovels, dragshovels, and draglines are confronted with the problem of selecting power-plant components which will give maximum performance during rapid load changes. To obtain design data, an engine alone and an engine torque-converter package were subjected to rapidly applied loads, and torques and speeds were recorded until steady-state conditions were reached.Analysis of test records indicates that significant losses in output power following rapid application of load are caused by the energy required for engine acceleration and by lower torque-converter efficiency during transient periods. Proper selection of components exploits the favorable factors and minimizes the others.DESIGNERS of excavating machinery such as shovels, dragshovels, and draglines are confronted with the problem of selecting power-plant components which will give maximum performance during rapid load changes. To obtain design data, an engine alone and an engine torque-converter package were subjected to rapidly applied loads, and torques and speeds were recorded until steady-state conditions were reached.Analysis of test records indicates that significant losses in output power following rapid application of load are caused by the energy required for engine acceleration and by lower torque-converter efficiency during transient periods. Proper selection of components exploits the favorable factors and minimizes the others.DESIGNERS of excavating machinery such as shovels, dragshovels, and draglines are confronted with the problem of selecting power-plant components which will give maximum performance during rapid load changes. To obtain design data, an engine alone and an engine torque-converter package were subjected to rapidly applied loads, and torques and speeds were recorded until steady-state conditions were reached.Analysis of test records indicates that significant losses in output power following rapid application of load are caused by the energy required for engine acceleration and by lower torque-converter efficiency during transient periods. Proper selection of components exploits the favorable factors and minimizes the others.