Abstract: A spring-hinged actuator has a first attachment member (1) joined pivotally to a second attachment member (2) with a hinge (3). The first attachment member and the second attachment member are spring-tensioned pivotally on the hinge with at least one torsional spring (4, 5) fastened to the first attachment member. At least one base torsional extension (6, 8) of the torsional spring is positioned to direct base torsional-spring pressure against the first attachment member in a first rotational direction and to direct torsionally rotative spring pressure in an oppositely second rotational direction against the second attachment member. The first attachment member and the second attachment member have sides at a dihedral angle proximate an axis of the hinge. The dihedral angle is maintained in opposition to opposite-directionally rotative pressure from the torsional spring by a releasable tensioner (14) that is extended intermediate the first attachment member and the second attachment member.