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Concrete Pump Truck Hydraulic System Failed

Concrete pump truck diesel engine working principle

1. Burning preparation phase (ignition delay)

The period from the injection of fuel to the start of ignition is the combustion preparation phase. At this stage, the physical preparation of the fuel for heating, evaporation, diffusion and mixing with the gas stream, and the chemical preparation process such as decomposition and oxidation.

2. Fast burning stage

From the beginning of the fire to the maximum pressure in the cylinder when the stop of this stage. When a small amount of diesel ignition, the number of combustible gas mixture continues to increase the rapid spread of the flame, burning faster, high heat release rate. The pressure and temperature in the cylinder rise sharply. However, when the pressure is increased too fast, it will cause a great impact load on the crank and connecting rod mechanism, accompanied by a sharp percussion sound and rough working diesel engine, which should be limited. In order to make the diesel engine work smoothly, the maximum pressure increase rate should not exceed 292kPa ~ 588kPa / 1 ° (crank angle).

3. Main combustion stage (retarding period)

The stage from the point at which the pressure bursts to the point where the maximum combustion temperature appears is the main combustion stage. The characteristic of this stage is that the fuel injection has ended. Most of the fuel is burned during this period, releasing about 80% of the total heat and the gas temperature reaches the highest point. However, due to the piston down, the cylinder volume increases, so the pressure in the cylinder did not change much. Oil supply ends at this stage.

4. After burning stage

From the highest combustion temperature point to the end of the combustion stage. At this stage, oxygen has been consumed in large quantities, and the injected fuel injected later does not have enough oxygen to be combusted with it. In addition, the further downward movement of the piston reduces the pressure and the temperature in the cylinder to deteriorate the combustion conditions, Resulting in incomplete combustion of the fuel, exhaust black smoke occurs, so that the heat load on the parts increases, affecting the economy and service life of diesel engines, it should minimize after-burning combustion.

Concrete pump truck hydraulic system failure, 75% are caused by pollution, overheating and into the air of these three factors. If you understand some of the basic principles, understand the main factors leading to failure, we can long-term to ensure that the system is in good working condition! Specific introduction is as follows:

1, the working oil due to enter the dirt and deterioration, into the oil in the dirt (such as ash, sand, soil, etc.) are:

(1) The system is not clean outside. The dirt is brought into the system when it is refueled or checked for oil, or it enters the system through a damaged oil seal or seal ring;

(2) internal cleaning is not complete. In the tank or components still leave traces of dirt residue;

(3) refueling containers or utensils dirty;

(4) due to the heat pipe when manufactured in the pipe rust scale;

(5) Improper storage of oil, dirty or deteriorated before joining the system;

(6) Metamorphic oil will corrode parts. Corroded metal may become free molecules suspended in oil.

2, overheating system overheating may be caused by one or more of the following reasons:

(1) air or moisture entering the oil, when the hydraulic pump to oil into pressure oil, the air and moisture will help increase the heat caused by overheating;

(2) the oil level in the container is too high, the oil is strongly stirred, causing overheating;

(3) poor quality oil may become thinner, foreign substances suspended, or have affinity with water, which can also cause heat generation;

(4) Exceeds the rated working capacity at work and thus generates heat;

(5) Return valve improperly adjusted, or damaged parts have not been replaced in a timely manner, sometimes generating heat.

3, into the air oil into the air for the following reasons:

(1) improperly pouring down when refueling, resulting in bubbles mixed into the oil and into the pipeline;

(2) loose joints or oil seal damaged, the air is inhaled;

(3) The suction line is worn through, scrape or corrode, so the air enters.

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