The diagnosis method of construction machinery and two kinds of common electrical faults     

The diagnosis methods of two common electrical faults of construction machinery are as follows:

1. oil pressure gauge pointer not moving

The fault is that when the ignition switch is switched on and the engine is started, the pointer of the oil pressure indicator does not act. The diagnosis method of this fault is as follows:

Turn the ignition switch, start the engine, the engine oil pressure sensor terminal ground. If the indicator of the oil pressure indicator moves at this time, the pressure gauge is in good condition, and the fault may be in the oil pressure sensor or the oil circuit. The sensor can be removed, with a flat stick against the diaphragm inside the sensor, if the hands do not move, then the fault sensor for damage. If the hands move, then the fault in the oil path.

The engine oil pressure sensor terminal ground, if the oil pressure gauge pointer does not move, the fault may be in the oil pressure gauge, oil pressure sensor connecting wire. Check the oil pressure gauge power wiring whether there is electricity, if the power supply wiring is no electricity, then explain the power line open circuit breaker. If the power supply wiring is power, check the oil pressure gauge signal line whether there is electricity, if there is electricity, then the fault in the oil pressure gauge. If there is no electricity, the wire between the oil pressure gauge and the sensor is broken.

2. generator without voltage output

The fault is that when the ignition switch is switched on and the engine is started, the generator has no voltage output.

There are 2 main reasons for the fault: one is the generator fault, the other is the voltage regulator failure. Two. The fault diagnosis method is as follows:

(1) generator fault diagnosis method

Check the generator tape to check if the generator tape is good and the tension is right. If the belt is worn, it should be replaced. If the belt tension is not enough, it should be tightened according to the requirements.

The following table is connected with the voltage and current meter method: engine shutdown, pull down a wire wire and generator "B" on the terminal of the battery, the 1 range is 0 ~ 50A DC ammeter is connected in series between the demolition of wire and the "B" terminal, another 1 range is 0 ~ 50V DC voltage meter, parallel to the generator.

Check the voltage and current to disconnect all the power equipment switches on the construction machinery to reduce the load of the generator. Connect the battery line, start the engine, make the generator run at a little higher than the full load speed, observe the ammeter indicating value should be less than 10A, the voltmeter indication value should be in the regulator rated voltage range. Put on the main lighting equipment, such as lighting, steering lamp, warm air and so on, observe the indication value of current meter should be greater than 30A, indicating value of voltmeter should be greater than rated voltage. If the detection value does not meet the above standard value, it shows that the generator is out of order.

(2) regulator fault diagnosis method

The method of measuring magnetic field current can be used to judge whether the transistor regulator is good or bad. Specific methods are as follows: in the regulator "F" and the generator "F" terminal string in series with 1 10A range of DC ammeter, start the engine, let the generator power generation.

When the engine speed is rising, if the pointer position of the ammeter is not moving, it indicates that the high power triode (or compound tube) is broken in the transistor regulator, or the voltage regulator tube and the short circuit of the small power transistor are short circuited.

If the current value indicates the stability in low speed, when the speed is 800 ~ 1000r/min, current meter indication value increasing with the increase of rotational speed, for large power triode (or composite pipe) or short circuit, voltage regulator tube, small power triode circuit breaker.

When the current meter is stable at low speed, when the speed is between 800 and 1000r/min, the indicator value of the ammeter decreases gradually with the increase of the speed, which shows that the regulator is good.