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 "M" type three-valve atresia loop separate hydraulic jacks, when lYA, when 2YA all power, three-valve in the neutral position, hydraulic cylinder two oil ports were closed, two-chamber filled with fluid cylinder, the cylinder in place to stay "locked", without outside interference. Because valve is sealed by a gap, so there is a leak jack manufacturers, 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 part of the system or systems jack in order to achieve the regulator, pressure, pressure, unloading and other control thin jack 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. A single-acting jack (single acting hydraulic jack) uses the Company's production of RC series of single-acting jack (single acting jack), designed with safety packing device, built-in pressure relief valve to prevent overload, to protect the jack in order to facilitate safe operation. All models are available according to customer requirements and neck dragonfly pattern, bottom mounting holes design makes positioning easy to install package. Mainly used for electric power, construction, machinery manufacturing, mining, railway bridges, shipbuilding and other industries to install equipment from the top demolition job. Second, the characteristics of a single-acting piston jack parts welding of copper, chrome plated piston rod batter, never pull the cylinder, wear strong. Two single-acting design, spring retraction (reset) 3 paint surface to make corrosion-resistant 4 dust ring to reduce pollution and extend the service life of a thin cylinder of the hydraulic jack _ Lu (certified) _ Jack Lu of hydraulic equipment from Texas plant available. 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.