Some mixer drivers reported that the engine of the same mixer purchased at the same time with a friend would have problems after using the vehicle for a period of time, but the engine of the friend's vehicle was OK. What is the matter? Let's get to know.
1. improper application of maintenance data of mixer truck
The failure to scientifically select maintenance data in the maintenance of mixer truck is an important reason for the early damage of mechanical parts. For example, the width of the contact surface between the valve and the valve seat is specified as 1-2.2mm for the inlet valve and 1.5-2.5mm for the exhaust valve. However, in the actual maintenance, many people think that it is better to be a little wider than a little narrower. They are used to selecting the upper limit or close to the upper limit, because the width of the valve working surface just repaired is close to the service limit. Another example is the valve foot clearance, which is generally 0.2-0.25mm for vehicles, but it is also considered that a larger clearance is better than a smaller clearance in maintenance and adjustment. Therefore, when the upper limit is exceeded, in fact, the clearance is too large, which not only reduces the engine power, but also causes knocking and early damage.
2. smooth grinding of valve
During the maintenance of the mixer truck, if the valve is ablated, pitted or sunken, it should be polished, usually on the grinder. Four problems should be paid attention to during the operation: first, ensure that the valve head is concentric with the rod, otherwise it should be straightened first; Second, on the premise that the smooth grinding vehicle can grind a complete cone, the smaller the better; Third, try to improve the surface finish; Fourth, the depression at the end of the valve stem shall be ground flat.
3. hinge pin of valve guide
The fit clearance between the valve stem and the valve guide is the key to determine the service life of the valve guide. Therefore, when replacing the new valve guide, the fit clearance shall be strictly controlled during hinge pin. The lower limit of the clearance shall be specified for each mixer model to effectively extend the service life.
4. grinding of valve
The grinding of valve can be divided into two cases: one is that the valve and valve seat have only slight pitting, and there is no need for smooth grinding and grinding when hinge pin is used; Second, the valve and valve seat are polished and polished after hinge pin. The former shall be ground with full gold steel sand first, and then with fine emery after the pitting is removed, and then coated with engine oil for grinding until the sealing meets the requirements and the width meets the requirements. The latter shall be grinded only when the sealing performance fails to meet the requirements, but attention must be paid during operation to avoid excessive force. It is strictly prohibited to knock the valve up and down, otherwise concave sand marks will appear, affecting the maintenance quality.
The engine failure of concrete mixer truck is not terrible, but the terrible thing is that the maintenance is not correct, and the performance of the engine will only get worse and worse. The mixer truck is affordable. Now it's right to buy it.
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