升降貨梯http://www.weheartgrub.com/采用了液壓系統為主要的動力單元，進行正常的升降運行。當升降貨梯液壓系統中有兩個以上的執行機構時，為使兩個執行機構按一定順序動作，便需采用順序閥。
Cargo lifter with a hydraulic system as the main power unit, normal lift operation. When cargo lifter hydraulic system has two or more actuators, in order to make the two actuators according to certain sequence of actions, it requires the use of sequential valve.
 
升降貨梯工作機構的順序動作可采用多種控制方式來實現，如機械的、電氣的及液壓的等，順序閥是采用液壓方式進行順序動作控制的閥類。升降貨梯順序閥也有直動式和導閥控制式兩種，其結構和工作原理與滋流閥、安全閥相似。進口油壓通過閥芯上的軸向孔引至閥芯底部，和調定的彈簧力相平衡。進口油壓低于彈簧調定壓力時，閥芯切斷進出油路，當進口油壓高于彈簧調定壓力時，閥芯抬起，進出油路接通。升降貨梯的順序閥密封性要求較高，滑閥的封油長度較長，以避免因泄漏而影響升降貨梯機構順序動作的可靠性。順序閥的排油口為工作油壓，因此彈簧腔的泄油管應直接引回油箱，而不能象滋流閥那樣在閥內和回油口相接。升降貨梯的結構與滋流閥職能符號的差別是有單獨的泄油口，出口是二次壓力油路，不接油箱。
Cargo lifter working bodies of the sequence of actions can be used to implement a variety of control methods, such as mechanical, electrical and hydraulic, etc., sequence valve is hydraulically sequential operation control valves. Cargo lifter sequence valve also has direct-acting and pilot-type two, the structure and works with AIDS valve, safety valve similar. Import oil through the axial hole lead on the spool to the bottom of the valve body, and it is set spring force equilibrium. Import oil pressure falls below the set pressure of the spring, the spool cutting out the oil, imported oil is higher than the spring when a set pressure, the valve lift, turned out the oil. Higher cargo lifter sequence valve sealing requirements, longer length of seal oil slide valve in order to avoid leakage and cargo lift mechanism sequence of actions affecting reliability. Sequence valve discharge port of the working oil pressure, and therefore the spring chamber drain line should be drawn directly back to the tank, but did not like mayonnaise valve in the valve and back to the oil port phase. Differences in the structure and function symbols AIDS valve cargo lift is a separate drain port, export is secondary pressure oil passage, do not take the tank.
 
升降貨梯http://www.weheartgrub.com/為順序閥的一種應用方法，油缸1驅動鉆頭鉆削完畢退回終點后，油路壓力升高，順序閥打開，于是油缸動作，驅動刀具進行切斷。
The latter application methods cargo lift to order valve cylinder driving drill drilling is completed to return the end, the oil pressure increases, the sequence valve opens, so the cylinder moves, drive for cutting tools.