A jacking device, including: a base member, including a base surface adapted to engage a substrate surface, having a base screw thread; an upper member, having an upper surface adapted to engage a load to be raised or lowered, having an upper screw thread; at least one intermediate member, positioned between said base member and said upper member, each intermediate member including first and second screw threads adapted to engage a respective screw thread of an adjacent member; drive means, adapted to permit movement of at least one of said members relative to its adjacent member to thereby raise or lower said upper surface, characterised in that said drive means includes: a primary hydraulic drive cylinder positioned between said base surface and said upper surface to substantially vertically raise/lower said upper surface relative to said base surface; and, a backup electric drive motor to rotate said intermediate member; a linear bearing, to substantially prevent rotational movement of said upper and base members whilst permitting rotation of said intermediate member as said drive means is operated; a controller, operable by a user to control the raising/lowering of said jacking device and to operate said drive means, wherein said controller controls the simultaneous operation of said drive means to thereby effect substantially vertical movement of said upper surface relative to said base surface via said primary drive cylinder, and, permit cooperative rotational movement of said intermediate member via said backup drive motor. a base member, including a base surface adapted to engage a substrate surface, having a base screw thread; an upper member, having an upper surface adapted to engage a load to be raised or lowered, having an upper screw thread; at least one intermediate member, positioned between said base member and said upper member, each intermediate member including first and second screw threads adapted to engage a respective screw thread of an adjacent member; drive means, adapted to permit movement of at least one of said members relative to its adjacent member to thereby raise or lower said upper surface, characterised in that said drive means includes: a primary hydraulic drive cylinder positioned between said base surface and said upper surface to substantially vertically raise/lower said upper surface relative to said base surface; and, a backup electric drive motor to rotate said intermediate member; a linear bearing, to substantially prevent rotational movement of said upper and base members whilst permitting rotation of said intermediate member as said drive means is operated; a controller, operable by a user to control the raising/lowering of said jacking device and to operate said drive means, wherein said controller controls the simultaneous operation of said drive means to thereby effect substantially vertical movement of said upper surface relative to said base surface via said primary drive cylinder, and, permit cooperative rotational movement of said intermediate member via said backup drive motor. a primary hydraulic drive cylinder positioned between said base surface and said upper surface to substantially vertically raise/lower said upper surface relative to said base surface; and, a backup electric drive motor to rotate said intermediate member; a linear bearing, to substantially prevent rotational movement of said upper and base members whilst permitting rotation of said intermediate member as said drive means is operated; a controller, operable by a user to control the raising/lowering of said jacking device and to operate said drive means, wherein said controller controls the simultaneous operation of said drive means to thereby effect substantially vertical movement of said upper surface relative to said base surface via said primary drive cylinder, and, permit cooperative rotational movement of said intermediate member via said backup drive motor.