A lifting column includes a drive unit, a lifting tube, and a transmission assembly. The lifting tube includes a first tube, a second tube, a third tube, a fourth tube, and a fifth tube. The transmission assembly includes a first screw rod, a second screw rod, a third screw rod, and a fourth screw rod. The drive unit is in transmission fit with the first screw rod and drives the first screw rod to rotate. A lower end of the second screw rod has a first nut in transmission with the first screw rod, a lower end of the third screw rod has a second nut in transmission with the second screw rod, a lower end of the fourth screw rod has a third nut in transmission with the third screw rod, and a lower end of the first tube has a fourth nut in transmission with the fourth screw rod.

A linear lifting device including a lifting column, a synchronous adjusting mechanism, a first motion element and a second motion element is provided. The lifting column has a fixed end and a movable end. The synchronous adjusting mechanism, disposed on the movable end, has a first force-bearing end and a second force-bearing end, which are respectively separated from the center of the synchronous adjusting mechanism by a rotating radius and remain at a synchronous state. The first and second elements respectively connect the first and second force-bearing ends for generating a first force to push the first force-bearing end to move in a first force direction and generating a second force to push the second force-bearing end to move in a second force direction, such that the movable end can move with respect to the fixed end in a resultant force direction of the first and second force directions.

A linear lifting device including a lifting column, a synchronous adjusting mechanism, a first motion element and a second motion element is provided. The lifting column has a fixed end and a movable end. The synchronous adjusting mechanism, disposed on the movable end, has a first force-bearing end and a second force-bearing end, which are respectively separated from the center of the synchronous adjusting mechanism by a rotating radius and remain at a synchronous state. The first and second elements respectively connect the first and second force-bearing ends for generating a first force to push the first force-bearing end to move in a first force direction and generating a second force to push the second force-bearing end to move in a second force direction, such that the movable end can move with respect to the fixed end in a resultant force direction of the first and second force directions.

A trailer tongue jack is convertible between operation by an integral actuator and an external actuator. The jack includes a clutch mechanism or coupler operable to selectively engage a drive screw with the integral actuator or the external actuator.

A trailer tongue jack is convertible between operation by an integral actuator and an external actuator. The jack includes a clutch mechanism or coupler operable to selectively engage a drive screw with the integral actuator or the external actuator.

A portable wheel lifting system to assist in the replacement of a wheel on a vehicle utilizing a portable outer housing, an inner lifting linkage system to hold a wheel or tire in place, and an electrical motor to vertically raise the lifting linkage system and thus the wheel to the desired location.

The linear actuator comprises upper and lower frame portions vertically movable relative to one another along a central axis, and first and second bands that intertwine to form an extractable and retractable column. The second band forms the wall of the vertical column, and it is the second band that is supported by a rotor that is rotatably carried by the lower frame portion, to reduce the mechanical stress on the first band.

The linear actuator comprises upper and lower frame portions vertically movable relative to one another along a central axis, and first and second bands that intertwine to form an extractable and retractable column. The second band forms the wall of the vertical column, and it is the second band that is supported by a rotor that is rotatably carried by the lower frame portion, to reduce the mechanical stress on the first band.

A lifting mechanism for gym equipment to provide height adjustment of the gym equipment and reduction of the thickness of the mechanism, having a bracket, a bearing rotational shaft, bearing wheels, a sleeve pipe, and a driver; the bracket is mounted to a gym equipment structural frame; the bearing rotational shaft is rotationally mounted between two ends of the bracket, a peripheral surface of the bearing rotational shaft is connected to linkage arms orienting to a same direction, and a wheel is mounted to each linkage arm; the sleeve pipe is pivotally connected to the bracket; the driver is pivotally connected to the bracket; an output end of the driver is a screw bolt; the screw bolt passes through the sleeve pipe.

A lifting mechanism for gym equipment to provide height adjustment of the gym equipment and reduction of the thickness of the mechanism, having a bracket, a bearing rotational shaft, bearing wheels, a sleeve pipe, and a driver; the bracket is mounted to a gym equipment structural frame; the bearing rotational shaft is rotationally mounted between two ends of the bracket, a peripheral surface of the bearing rotational shaft is connected to linkage arms orienting to a same direction, and a wheel is mounted to each linkage arm; the sleeve pipe is pivotally connected to the bracket; the driver is pivotally connected to the bracket; an output end of the driver is a screw bolt; the screw bolt passes through the sleeve pipe.