Abstract: A hydraulic cylinder structure contains: a hydraulic cylinder including a movable piston rod, a connecting seat, and an oil tank having an outer tube and an inner tube. The piston rod is hollow and is fitted with a guiding tube of the connecting seat, and a pump of the connecting seat has an oil feeding pipe for outputting hydraulic oil. The oil feeding pipe is in connection with the guiding tube, an on/off valve, a pressure adjusting valve, and a safety valve. The pressure adjusting valve is coupled with an oil path of a push piston, and the oil path is joined with an auxiliary path and the on/off valve for drawing the hydraulic oil out of the oil tank via a single-direction valve, and the on/off valve and the safety valve are connected with the oil tank.

Abstract: An extensible and turnover handle structure for a jack comprises a pivot ear formed at the front end of a base. The pivot ear is provided for a pivot connection with the handle. Moreover, the handle includes an inner pipe inserted in an outer pipe and serves to draw out the inner pipe in use, thus elongating an arm of force relative to the base, and the handle can be turned to a position above a top plate to reduce volume during storage.