1. Improper use of maintenance data of small mixer: failure to select maintenance data scientifically in the maintenance of small mixer is an important reason for premature damage of parts. For example, the width of the contact surface between the valve and the valve seat is specified as 1-2.2mm for the intake valve and 1.5-2.5mm for the exhaust valve. However, in the actual maintenance, many people think that it is better to be wide than narrow, and usually choose the upper limit or close to the upper limit. Because the width of the valve working surface of the newly repaired car is close to the service limit. Another example is the valve seat clearance, which is usually specified as 0.2-0.25mm of the vehicle. However, in the maintenance adjustment, the clearance greater than or less than the clearance should also be considered. Therefore, if the clearance exceeds the upper limit, the clearance is actually too large, which will not only reduce the engine power, but also cause early damage due to impact.
2. Smooth grinding of valve: in the maintenance of small mixer, if the valve is ablated, dented or sunken, it should be polished, usually on a smooth grinder. In the process of operation, we need to pay attention to four problems: ensure that the valve head is concentric with the valve stem, otherwise it should be straightened first; the second point is that if the complete cone can be ground out, the smooth car should be as small as possible. The third is to improve the surface finish as much as possible. Fourth, the end of the stem is concave and should be grounded.
3. Hinge pin of valve guide: the clearance between valve stem and valve guide is the key to determine the service life of valve guide. Therefore, when replacing the new valve guide, the clearance of hinge pin should be strictly controlled, and the clearance specified by each small mixer model number should be used. It can effectively prolong the service life.
4. Grinding of valve: grinding of valve can be divided into two cases: one is that there is only slight pitting corrosion on valve and valve seat, and there is no need for grinding and hinge pin grinding. The other is that the valve and seat are polished and hinged. After grinding, the former is first ground with pure steel sand, then the pits are ground off, then ground with fine emery, and finally coated with engine oil for grinding until the seal meets the requirements and the width meets the requirements. The latter is only grounded when the seal does not meet the requirements, but in the process of operation, care must be taken not to use too much force. It is strictly forbidden to knock the valve up and down, otherwise concave sand marks will appear, which will affect the maintenance quality.
Concrete mixer engine failure is not terrible. The terrible thing is that if the maintenance is not correct, the performance of the engine will only deteriorate. The price of small mixer is moderate. Buy it now.