SOLUTION

The excavators are used for lifting or lowering a load. They are used for digging the ground hence the bucket connected to the excavator always carry the heavy load such as soil, rock etc.  For such an application, high starting torque is required therefore DC series motor is best suited.

In a DC series motor, the field winding and armature winding are in series connection. Since the flux produced is directly proportional to the armature current, torque is directly proportional to the square of the armature current. Thus more current is drawn than the DC shunt motor and hence more torque is produced.