Hybrid drive train for self propelled power trowel

A hybrid drive train for a self propelled power trowel, comprising:

• a rigid frame having a front and a rear and defining a centerline from front to rear;
• means for providing DC power to said power trowel attached to the rigid frame;
• means for inverting the DC power into an AC output;
• a pair of rotatable rotor assemblies tiltably connected to the rigid frame and configured to contact a concrete surface below the rigid frame and to support the rigid frame thereabove;
• one or more electrical motors electrically connected to the AC output and operatively connected to the rotatable rotor assemblies to cause rotation of said rotor assemblies;
• means for tilting each rotor assembly toward and away from the centerline of the frame;
• and
• means for tilting at least one of the rotor assemblies fore and aft, parallel to the centerline of the frame.

A hybrid drive train for a self propelled power trowel, comprising:

• a frame;
• an engine-generator set attached to the frame and configured to provide electrical power to the power trowel;
• a pair of rotatable rotor assemblies tiltably connected to the frame and configured to contact a concrete surface below the frame and to support the frame thereabove;
• one or more rectifiers attached to the frame and configured to convert the electrical power from the engine-generator set to DC power;
• one or more inverters attached to the frame and configured to convert the DC power to AC output;
• and
• one or more brushless AC synchronous motors electrically connected to the one or more inverters and operatively connected to the rotatable rotor assemblies to cause rotation of said rotor assemblies.