Hydraulics components prone to noise is generally considered to pumps and valves, Tongchuan roller hydraulic maintenance, relief valve and solenoid valve again based. Many factors generate noise. Noise relief valve has a flow rate of two kinds of sound and mechanical sound. Mainly by the fluid flow rate the sound vibration, a hole, and hydraulic shock causes noise. Mechanical sound consists of valve and other parts of the impact and friction causes noise. For self-suction-type piston pump, the hydraulic oil tank must not fall below the lower limit of the oil standard, to maintain a sufficient amount of hydraulic oil. Cleanliness of hydraulic oil higher, longer pump life.