This standard specifies the general requirements, performance requirements, test conditions, test equipment, test methods, type test and factory test, inspection rules and signs, packaging, transportation and storage of the dump valve. This standard applies only to hydraulic oil as the working medium for dump truck lifting system with manual, pneumatic and hydraulic directional valve (hereinafter referred to as valve). 2 Standard QC / T460 Dump Truck - Technical Specifications of Hydraulic Cylinder QC / T484 Automotive Paint Coat GB / T3766 General Technical Requirements for Hydraulic System GB / T2828 Sampling Procedure and Sampling Table for Batch Inspection 3 General Requirements 3.1 Directional Valve Shall comply with the provisions of this standard and shall be manufactured in accordance with the drawings and technical documents approved by the prescribed procedures. 3.2 All parts subject to inspection by the quality inspection department before they can be assembled. 3.3 Nominal valve pressure to be selected with reference to QC / T460 "dump truck - hydraulic cylinder technical conditions," the relevant provisions. 3.4 valve inlet and outlet ports and other parts should be taken rust, dust and other protective measures. The remaining surface paint by QC / T484 Table 1 TQ6 provisions of the paint. 3.5 All seals, dust-proof parts in the assembly should be coated with oil or thin layer of grease, and should ensure that no damage to the seal. 3.6 casting surface should be smooth, not sticky sand, cracks, burrs and other harmful defects. 3.7 The valve should be cleaned before assembly. 3.8 manual valve control force should meet the relevant requirements GB / T3766. 4 Performance requirements 4.1 Commissioning to the valve in the nominal pressure, rated flow conditions should be flexible to the direction of abnormal sound should not occur, the pressure oil conversion direction should be accurate. 4.2 Pressure Loss Under rated flow conditions, the pressure loss of each channel of the valve shall not exceed 0.3MPa. 4.3 Internal Leakage Internal leak test, the valve leakage per minute shall not exceed 0.6% of the rated flow. Note: The specified value of the internal leakage of any working position when the total leakage of each measuring port. 4.4 Pressure Withstanding voltage test, the valve shall not rupture, all parts shall not appear anomalies such as oil dripping. 4.5 Durability Durability test should meet the requirements of 4.2 and 4.3. 5 test conditions 5.1 oil temperature test into the test valve when the oil temperature is 50 ℃, the steady-state allowable variation range should be consistent with the provisions of Table 1. Table 1 Allowable range of oil temperature ℃ Measuring level ABC Allowable range of variation of oil temperature ± 1.0 ± 2.0 ± 5.0 5.2 Viscosity The kinematic viscosity of oil is 17 × 10-6 ~ 43 × 10-6m2 / s at 50 ℃ . 5.3 Filtration Accuracy of oil filtration precision of not less than 25μm. 5.4 Test Equipment, Instrument Accuracy 5.4.1 According to A, B, C three measurement levels to select the appropriate test equipment, instruments, type test should not be less than the B-level measurement, the factory test should be not less than C Level measurement level.
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