Tensioner with single torsion spring having multiple nested windings

A tensioner comprising:

• a support member including a pivot shaft that defines a first axis;
• an arm having an arm arbor that is mounted on the pivot shaft for rotatable movement of the arm about the first axis, the arm arbor defining a cavity;
• a spring received in the cavity of the arm arbor and coupled to the arm, the spring comprising:
• an outer winding having an outer coil that defines an outer diameter;
• at least one inner winding having an inner coil that defines an inner diameter, the inner diameter of the inner coil being less than the outer diameter of the outer coil such that at least a portion of the inner winding of the spring is received by the outer winding of the spring, and wherein the outer winding and the inner winding of the spring both urge the arm arbor to rotate about the first axis into tensioning engagement with a power transmitting element;
• and
• a transition zone connecting the inner winding with the outer winding, wherein a portion of the spring bends between the inner winding and the outer winding in the transition zone.