## Principle and method of parameter measurement

As long as the operating parameters at any point required in the hydraulic system loop are measured and compared with the normal value of the system, it can be judged whether the operating parameters of the system are normal, whether the fault has occurred and where the fault is located.

Working parameters in hydraulic system such as pressure, flow and temperature are electrical quantities. When general instrument adopt indirect measurement method of measurement, first of all, it needs to use physical effect to converted these non-electricity into electricity, and then through the amplification, transformation and display processing, the measured parameters can be represented and displayed by the converted electrical signals. This can determine whether the hydraulic system fails. However, this indirect measurement method requires a variety of sensors, and the detection device is complex, and the measurement result error is large and not intuitive, which is not convenient for popularizing and using in the field.

Step 1: measuring the pressure. First, screwing the hose joint of the test loop and the three-way thread interface of the double ball valve. Opening ball valve 2. Closing overflow valve 3. Cutting off the oil return channel. At this time, the pressure value of the measured point (the actual working pressure of the system) can be read directly from the pressure gauge.

Step 2: measuring the flow and temperature. Slowly releasing the grip of the overflow valve 7 and closing the ball valve 1. Readjusting the overflow valve 7 so that the pressure gauge 4 reading is the measured pressure value. At this time, the flow meter 5 reading is the actual flow value of the measured point. At the same time, the temperature of oil can be shown on thermometer 6.

Step 3: measuring speed. Whether the speed of the pump, motor or cylinder depends only depend on two factors, including the flow rate and its own geometric size (displacement or area), so as long as the output flow of the motor or cylinder is measured (input flow rate to the pump), which divided by the displacement or area, so the value of speed or speed is obtained.