Lock-loop control loop by making the actuator during exercise at a location to stay for some time remain intact and prevent stop traverse. The hydraulic cylinder locking methods are adopted spool function for the "O" or lockout circuit jack "M" type three-valve, when lYA, when 2YA all power, three valves in the neutral position, two hydraulic cylinders an oil port was closed cylinder two chambers filled with fluid, the cylinder in place to stay "locked", without outside interference. Because valve is sealed by a gap, so there is a leak, the locking effect is not good, but simple structure. 2. The pressure control loop pressure control loop with a pressure valve to regulate the pressure of a portion of the system or systems, in order to achieve voltage regulation, reduced pressure, pressurization, unloading control, in order to meet the requirements of the actuator pressure. (1) refers to the voltage regulator circuit regulator loop control system operating pressure, it does not exceed the value of a good tune in advance, or at different stages of the actuator pressure multi-stage conversion in the work process. Generally consists of relief to achieve this functionality. Note a) if the phenomenon occurs when playing with an empty thin jack, can be relaxed to put oil on the screw pump, the pump vertically up and head down a few dozen empty 630t jacks, then tighten the oil drain bolt, you can continue use. b) When a load, avoid the quick connector Remove the jack 320, in order to avoid accidents and damage to the parts. c) This machine is oil as the medium, this equipment must be prepared to oil and maintenance work, in order to avoid blockage or leakage affect the results. d) new or long opposed hydraulic jack, have more memory because the air cylinder, the start of use, the piston rod may occur slight sudden jump phenomenon can be hydraulic jack load reciprocating motion 2-3 times, in order to exclude cavity air. Long idle jack, do not work long-term because of the seal and cause hardening of the seal, thus affecting the life of hydraulic jacks, hydraulic jack when not in use so a month to load reciprocating hydraulic jacks 2-3 . 320 Jack Lu Hydraulic (certified), DianJiangXian jack provided by the Texas Lu force hydraulic machinery plant. Texas Lu force hydraulic machinery plant (www.luliyeya.com) is a leader in Dezhou, hydraulic machinery and parts, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. Lu Hydraulic leadership with the staff warmly welcome all inquiries negotiations to create Lu hydraulic force a better future.