Maneuverable ergonomic trailer stands are disclosed. An example portable trailer stand includes a frame having an upper ledge; an extendible leg coupled to the frame, the upper ledge being vertically movable to selectively engage and disengage an underside of a trailer parked on a driveway based on movement of the extendible leg relative to the frame; a wheel connected to the frame, the wheel to remain at a substantially fixed distance from the upper ledge as the upper ledge is vertically moved.

Maneuverable ergonomic trailer stands are disclosed. An example portable trailer stand includes a frame having an upper ledge; an extendible leg coupled to the frame, the upper ledge being vertically movable to selectively engage and disengage an underside of a trailer parked on a driveway based on movement of the extendible leg relative to the frame; a wheel connected to the frame, the wheel to remain at a substantially fixed distance from the upper ledge as the upper ledge is vertically moved.

A lifting device includes a drive, a speed change gear device arranged above the drive and configured to be rotatable by means of the drive, a transmission device connected to the speed change gear device and a lifting mechanism fixed in the transmission device, and the speed change gear device is fixed to a side wall of the transmission device. Under an action of the drive and a speed change of speed change gear device, a gravity of a weight suspended on the lifting device is converted, so that the weight is lifted under a small force. The lifting device can also be driven via an electric hand tool. In addition, a first transmission device and a second transmission device are provided with a safety device to lock the lifting device when reaching a top, so as to prevent the lifting device from slipping to cause injuries.

A lifting device includes a drive, a speed change gear device arranged above the drive and configured to be rotatable by means of the drive, a transmission device connected to the speed change gear device and a lifting mechanism fixed in the transmission device, and the speed change gear device is fixed to a side wall of the transmission device. Under an action of the drive and a speed change of speed change gear device, a gravity of a weight suspended on the lifting device is converted, so that the weight is lifted under a small force. The lifting device can also be driven via an electric hand tool. In addition, a first transmission device and a second transmission device are provided with a safety device to lock the lifting device when reaching a top, so as to prevent the lifting device from slipping to cause injuries.

Maneuverable ergonomic trailer stands are disclosed. An example portable trailer stand includes: a frame having an upper ledge, a post, and a lower subframe, the lower subframe connected to the upper ledge via the post; an extendible leg coupled to the post independent of the lower subframe, the upper ledge being vertically movable based on movement of the extendible leg relative to the upper ledge, the post, and the lower subframe of the frame; and a wheel connected to the frame via the lower subframe such that the wheel is to move with the upper ledge as the upper ledge is vertically moved.

Maneuverable ergonomic trailer stands are disclosed. An example portable trailer stand includes: a frame having an upper ledge, a post, and a lower subframe, the lower subframe connected to the upper ledge via the post; an extendible leg coupled to the post independent of the lower subframe, the upper ledge being vertically movable based on movement of the extendible leg relative to the upper ledge, the post, and the lower subframe of the frame; and a wheel connected to the frame via the lower subframe such that the wheel is to move with the upper ledge as the upper ledge is vertically moved.

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 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 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.