DAMPING CIRCUIT FOR EXCAVATOR MULTI-MOTOR LOAD SHARING SWING DRIVE

The swing drive motor armatures on an excavator are connected in alternate fashion with the armatures of their associated generators to form a sandwiched loop. Sets of nodes which are at the same potential under steady state conditions are thus formed in the loop and a damping resistor is connected between a pair of these equal-potential nodes to conduct current when oscillations occur in the mechanical portion of the swing drive. As a result, the swing drive motors generate output torques which oppose and damp these oscillations. Alternative arrangements are shown in which four motor armatures and four generator armatures are connected in a single sandwiched loop, or in which a pair of sandwiched loops are formed with two motor armatures and two generator armatures in each loop.