Precautions for the use of instruments and sensors, common faults and troubleshooting methods

In construction machinery vehicles, the role of instruments and sensors is obvious. They effectively monitor the working status of the entire machine and its components. If it fails to work properly, information cannot be fed back to the operator, and thus potential faults cannot be detected in a timely manner.

I. Precautions for the Use and Installation of the Instrument.

1. The instrument must be used in conjunction with its matching sensor.

2 The wires should be connected reliably and must not come into contact with other metal conductors.

3 When installing or disassembling, do not strike or bump.

Ammeters and voltmeters should also be noted

1. The positive and negative polarities of an ammeter must not be reversed. Generally, in construction machinery, the entire vehicle is grounded with the negative pole. So, what does an ammeter have? The terminal should be connected to the positive terminal of the battery, and the "+" terminal should be connected to one end of the armature of the alternator (B+).

2 Before wiring the ammeter, the contact surfaces such as washers, nuts and bolts should be sanded clean with sandpaper. When installing the nuts, it is best to apply a little clean engine oil, which can not only prevent rust but also facilitate disassembly and assembly. The flat insulating gasket should be in good condition, and a flat gasket should be installed between the insulating gasket and the spring gasket and securely connected to prevent the wire end from overheating due to poor contact, which may even burn out the instrument and wire harness.

3 When wiring the ammeter and voltmeter, it is important to turn off the power supply of the entire vehicle to avoid short circuits.

4 The "+" terminal on the voltmeter is connected to the positive terminal of the battery. "?" Connect the terminal to the negative terminal of the battery. Do not connect it wrongly.

Ii. Precautions for the Use and Installation of Sensors.

Oil quantity sensor

1. The movement of the float in the fuel tank should be flexible; otherwise, inaccurate indication may occur due to interference between the float and the fuel tank partition.

2 The grounding of the oil quantity sensor should be reliable.

3 The resistance value of the variable resistance sensor of the moving magnetic fuel gauge will increase as the fuel level inside the fuel tank rises.

Temperature sensor

1. The grounding of the sensor should be reliable, and the wire connection of the sensor must not be short-circuited.

2 The thermistor of the magnetic water temperature gauge sensor will have its resistance value decrease as the temperature rises.

Pressure sensor

1. The variable resistance value of the moving magnetic pressure gauge increases as the pressure rises.

2 When installing the pressure sensor, do not twist the housing directly.

3 If the sensor gives an alarm, the sensor wire and the alarm wire must not be connected in reverse.

Rotational speed sensor

1. Ensure that the gap between the bottom of the sensor and the top of the engine teeth is 0.8 to 1.0 mm; otherwise, it will cause inaccurate indication. The correct installation method is to first screw the sensor to the bottom, that is, the bottom of the sensor touches the top of the engine flywheel teeth, then turn it counterclockwise by 2/3 turns, and finally tighten it with the back tightening nut.

2 At idle speed, the output induced voltage Urms of the speed sensor is greater than 1.0V.

Iii. Common Fault Diagnosis and Elimination Methods