SWING SYSTEM FOR A SURFACE MINING SHOVEL

摘要

A swing drive system for a surface mining shovel comprising an alternating current motor having a plurality of distributed rotor coils mounted on the lower body and a plurality of distributed stator coils connected to a power supply and mounted on the upper frame. Operation of the motor causes the upper body to rotate or swing relative to the stationary lower body. The rotatable upper frame and thereby the stator coils are movably supported on a circular track forming part of the lower stationary body by means of rollers positioned between the upper frame and the lower body. The upper frame may have a circular track facing the lower track and the rollers then roll on the lower circular track in engagement with both the upper and lower circular tracks to rotatably support the upper frame on the lower body. The rotor coils are preferably positioned between the rollers and the stator coils. The motor is supplied with three phase A.C. power from an inverter such that the frequency of the power to the motor can be adjusted to control the speed of the motor. The motor and thereby the swing of the rotatable upper frame can be stopped by controlling the inverter to change the sequence of two of the three phases of the power supplied by the inverter.