Elevator principle: hydraulic oil made certain pressure vane pump, the oil filter, flameproof electromagnetic directional valve, throttle valve, hydraulic control one-way valve, balance valve into the lower cylinder, the hydraulic cylinder piston upward movement, improve the weight, the upper cylinder oil return by the flameproof electromagnetic directional valve back to the fuel tank, the rated pressure through the overflow valve adjustment, observing the pressure gauge pressure gauge reading values. The hydraulic cylinder piston downward motion (both weight down). The oil in the hydraulic explosion-proof solenoid directional valve to enter the upper cylinder, and the lower cylinder oil return the balance valve, hydraulic control one-way valve, throttle valve, flameproof electromagnetic directional valve back to tank. To make the weight fall calm, safe and reliable braking, set the balance valve on back to oil, balance circuit, maintain pressure, make the falling speed is not affected by weight changes, the throttle valve flow adjustment, lifting speed control.In order to make safe and reliable braking, to prevent accidental, increase the hydraulic controlled check valve, hydraulic lock, ensure the safety of burst in hydraulic pipeline accident can self-locking. Installed the acoustic alarm overload to distinguish overload or equipment failure. Electronic control system can be explosion-proof buttons to control motor rotation, reversing the flameproof electromagnetic directional valve, in order to keep the load lifting or lowering, and adjust the amount of time delay, by the "LOGO" program to avoid motor caused by frequent starting of lift is not flexible, lag, prolong service life.