Adding a third hinge increases the rated hinge capacity by approximately 30%, IF the third hinge is located, as per Simonswerk's recommendation, at 14" below the upper hinge.

The centerline of the upper hinge, itself, should be located 10" from the top edge of the door.

Adding additional hinges beyond this does not increase the rated capacity.

Note also that the rated capacity must be reduced for doors over 39 inches in width. See the following document for further information...

Load Specification Guides for All Capacities