1 Subject Matter and Scope 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 reversing valve for dump trucks. 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 reference standard QC / T 460 dump truck - hydraulic cylinder technical conditions QC / T 484 automotive paint coating GB / T 3766 hydraulic system General technical conditions GB / T 2828 batch inspection count sampling procedures and sampling table 3 General requirements 3. 1 reversing valve shall comply with the provisions of this standard, and in accordance with the procedures approved by the drawings and technical documents. 3.2 All parts subject to inspection by the quality inspection department before they can be assembled. 3.3 The nominal pressure valve selection should refer to QC / T 460 "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 according to QC / T 484 TQ6 Table 1 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 Manually operated valves should meet the relevant requirements of GB / T 3766. 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 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. 5.4.2 When the controlled parameter indicates the range of change within the range specified in Table 2, then allow to record the test parameters measured values. Table 2 Controlled Parameter Indication Value Changeable Range Measurement Grade ABC Flow% ± 0.5 ± 1.5 ± 2.5 Pressure% ± 0.5 ± 1.5 ± 2.5 Temperature ℃ ± 1.0 ± 2.0 ± 5.0 Viscosity% ± 5 ± 10.0 ± 15 5.4.3 Test the use of test equipment, measuring instruments shall not exceed the measurement error of the provisions of Table 3. Table 3 Measurement tolerance of instruments and meters Measurement grade ABC Flow% ± 0.5 ± 1.5 ± 2.5 Pressure% ± 0.5 ± 1.5 ± 2.5 Temperature ℃ ± 0.5 ± 1.0 ± 2.0 Note: The range given in Table 3 is the instrument of choice, Instrument in the range of actual use tolerance range. 5.4.4 When writing a test report, the test level of the test shall be indicated. 6 test device 6.1 pressure measuring point position 6.1.1 near the mouth pressure measuring point at the location of the disturbance source (such as valves, elbows) and upstream of the test valve, the distance from the disturbance source is not less than 10d, and the test valve should be not less than 5d (d is the pipe diameter).
