Abstract :
An introductory paper on this subject is considered timely in view of the growing importance of electrically equipped excavators of the single-bucket type and of the lack of previously published information on the subject in the Journal. After describing their sphere of application and commenting on the increasing importance of electric drive, an explanation is given of the fundamental motions and structural limitations of these machines. A summary of the special service conditions precedes a discussion on electric drive methods for the two main groups of excavators, the ¿friction¿ type and the individual-drive machine where the application of the modern Ward-Leonard system with 3-coil dynamo and separately-excited motor is referred to in some detail. Main and auxiliary equipment is dealt with from the electrical and mechanical aspects: installation and wiring details are supplemented by illustrations of typical equipment layouts and wiring diagrams. Attention is drawn to certain special aspects of power supply and distribution to excavating projects, representative power consumption details being given. Concluding remarks discuss some possible future developments in electrical applications to this type of machinery.
