A manual trailer lifting jack with drill power option includes: an outer tube; an inner tube that is telescopically slidable within the outer tube; a foot that is connected to a bottom of the outer tube; a top block that is connected to a top of the outer tube; a threaded rod that pass through a center of the top block and is rotatably held within the outer tube and fixed from axial movement relative to the outer tube; a threaded block that is connected to a top of the inner tube and has threads that engage the threaded rod so that a rotation of the threaded rod causes the inner tube to slide axially within the outer tube; a driving gear that is connect the top block and drives the threaded rod; a gear shaft that includes a bevel gear and a hexagonal head; and a gear housing that houses the gear shaft, driving gear, and the top block.

A jack assembly is shown and describe. The jack assembly may include a first tube having first and second end portions and a central portion between the first and second end portions, and a second tube positioned within the first tube and movable with respect to the first tube. The jack assembly may also include an expanded portion on the first tube, the expanded portion having a larger inner diameter than an inner diameter of the central portion, and a bushing attached to the expanded portion, where the bushing generally prevents contact between the first and second tubes.

A jack assembly is shown and describe. The jack assembly may include a first tube having first and second end portions and a central portion between the first and second end portions, and a second tube positioned within the first tube and movable with respect to the first tube. The jack assembly may also include an expanded portion on the first tube, the expanded portion having a larger inner diameter than an inner diameter of the central portion, and a bushing attached to the expanded portion, where the bushing generally prevents contact between the first and second tubes.

A transmission assembly for a lifting column is provided. The lifting column includes an inner tube. The transmission assembly includes a hollow spindle, a transmission screw, a sleeve sleeved over the hollow spindle, a guide tube limited in the sleeve, and an actuating device actuating the guide tube to rotate. The guide tube and the hollow spindle are synchronously rotatable and axially expandable and retractable relative to each other. The transmission screw and the hollow spindle are synchronously rotatable and are axially expandable and retractable relative to each other. The actuating device is disposed in the inner tube and securely mounted to an upper end of the sleeve. A lower end of the sleeve is securely connected with a first transmission nut that is threadedly-fitted with the hollow spindle, the first transmission nut is securely coupled to the inner tube, and the upper end of the sleeve is movably disposed.

A transmission assembly for a lifting column is provided. The lifting column includes an inner tube. The transmission assembly includes a hollow spindle, a transmission screw, a sleeve sleeved over the hollow spindle, a guide tube limited in the sleeve, and an actuating device actuating the guide tube to rotate. The guide tube and the hollow spindle are synchronously rotatable and axially expandable and retractable relative to each other. The transmission screw and the hollow spindle are synchronously rotatable and are axially expandable and retractable relative to each other. The actuating device is disposed in the inner tube and securely mounted to an upper end of the sleeve. A lower end of the sleeve is securely connected with a first transmission nut that is threadedly-fitted with the hollow spindle, the first transmission nut is securely coupled to the inner tube, and the upper end of the sleeve is movably disposed.

A linear jack includes an outer tube, a high speed assembly comprising a first rotating member threadedly coupled to a first translating member, a low speed assembly comprising a second rotating member threadedly coupled to a second translating member, wherein the low speed assembly is coupled to and translates with the first translating member. At least a portion of the high speed assembly is slidable in the outer tube between a first position, wherein the high speed assembly is engaged with a shaft, and a second position, wherein the high speed assembly is disengaged from the shaft. A thread pitch of the high speed assembly is greater than a thread pitch of the low speed assembly.

A jack (1), which is extensible, comprising: a first tubular body (5), a second tubular body (30) slidably associated with the first tubular body (5) and movable along a predetermined longitudinal direction (A), a third tubular body (95) slidably associated with the second tubular body (30) and movable along the longitudinal direction (A), a base (115) for support associated with an end (105) of the third tubular body (95) distal from the second tubular body (30), characterized in that it comprises an automatic safety device (145) provided with a lockbolt (150) movable between a first position, wherein it allows relative sliding between the third tubular body (95) and the second tubular body (30), and a second position wherein it prevents the third tubular body (95) from sliding relative to the second tubular body (30).

A jack (1), which is extensible, comprising: a first tubular body (5), a second tubular body (30) slidably associated with the first tubular body (5) and movable along a predetermined longitudinal direction (A), a third tubular body (95) slidably associated with the second tubular body (30) and movable along the longitudinal direction (A), a base (115) for support associated with an end (105) of the third tubular body (95) distal from the second tubular body (30), characterized in that it comprises an automatic safety device (145) provided with a lockbolt (150) movable between a first position, wherein it allows relative sliding between the third tubular body (95) and the second tubular body (30), and a second position wherein it prevents the third tubular body (95) from sliding relative to the second tubular body (30).

A jack assembly is shown and describe. The jack assembly may include a first tube having first and second end portions and a central portion between the first and second end portions, and a second tube positioned within the first tube and movable with respect to the first tube. The jack assembly may also include an expanded portion on the first tube, the expanded portion having a larger inner diameter than an inner diameter of the central portion, and a bushing attached to the expanded portion, where the bushing generally prevents contact between the first and second tubes.

A jack assembly is shown and describe. The jack assembly may include a first tube having first and second end portions and a central portion between the first and second end portions, and a second tube positioned within the first tube and movable with respect to the first tube. The jack assembly may also include an expanded portion on the first tube, the expanded portion having a larger inner diameter than an inner diameter of the central portion, and a bushing attached to the expanded portion, where the bushing generally prevents contact between the first and second tubes.