| CPC B66F 3/10 (2013.01) [B66F 3/44 (2013.01)] | 20 Claims |

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1. A jack comprising:
an outer tube;
a middle tube concentrically received in the outer tube;
an inner tube concentrically received in the middle tube;
a lead screw received in the middle tube;
a traveling nut affixed to a top of the middle tube threadedly engaged with the lead screw;
said outer tube and middle tube having a cooperative dimple and groove structure to prevent the middle tube from rotating relative to the outer tube;
said middle tube and inner tube having a cooperative dimple and groove structure to prevent the inner tube from rotating relative to the middle tube;
said lead screw having a collar with a diameter larger than a threaded portion of the lead screw at an upper end of the lead screw with a first unthreaded portion adjacent to the collar and with a first spring positioned over the first unthreaded portion between the collar and a the threaded portion of the lead screw;
said lead screw having a stop with a diameter larger than the threaded portion of the lead screw at an lower end with a second unthreaded portion adjacent to the stop and with a second spring positioned over the second unthreaded portion between the stop and a the threaded portion of the lead screw.
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