Abstract: The present jack apparatus is particularly adapted for heavy duty lifting. The jack apparatus includes a base; a pair of screw jacks; a yoke supported by the screw jacks; a lifting tube supported on the yoke; a shaft coupler coupling the screw jacks; a power unit driving one of the screw jacks and through the shaft coupler also driving the other screw jack; and a housing covering the screw jacks and other components. The pair of screw jacks each have threaded lifting shafts designed to eliminate risk of unexpected lowering of the jack's lifting tube even if power is lost. A jack system is described including two or more of the jack apparatus controlled by a single control for simultaneous operation.

Abstract: The present jack apparatus is particularly adapted for heavy duty lifting. The jack apparatus includes a base; a pair of screw jacks; a yoke supported by the screw jacks; a lifting tube supported on the yoke; a shaft coupler coupling the screw jacks; a power unit driving one of the screw jacks and through the shaft coupler also driving the other screw jack; and a housing covering the screw jacks and other components. The pair of screw jacks each have threaded lifting shafts designed to eliminate risk of unexpected lowering of the jack's lifting tube even if power is lost. A jack system is described including two or more of the jack apparatus controlled by a single control for simultaneous operation.