| 摘要 |
An oil circuit of a jack for rising an object to a preset position rapidly, wherein the oil inlet circuit of a hydraulic loop system is improved. An oil channel is installed between the inner oil chamber of the piston rod and the sequential valve. A check valve is installed between the oil channel and the sequential valve. An oil channel is installed between the sequential valve and the check valve for being connected to the inner oil chamber of the piston rod. By changing the positions of the check valve and the oil channel. When in the working conditions of dump load or light load, the sequential valve is closed, thus, the hydraulic oil may enter into the inner oil chamber of the piston rod from the pumping oil chamber through the check valve so that the piston rod will rise rapidly to a still condition. In the still condition, since the check valve closes the oil channel, the sequential valve will open automatically so that the inner oil chamber of the piston rod is communicated to the inner oil reservoir. Thus the inner and outer oil pressures of the oil guiding tube in the piston rod are equal. Thus, no strong still load hydraulic pressure exists in the oil guiding tube within the inner oil chamber of the piston rod. BY this changing, the still load hydraulic pressure of the inner oil reservoir and the inner oil chamber of the piston rod can be adjusted equilibrium by the sequential valve. Therefore, the problem of breakage of the oil guiding tube of the piston rod and the high cost due to confinement in material are solved. Moreover, the sequential valve can be located outsides so that the sequential valve is adjustable at outside to a preset actuating pressure.
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