1. Improper application of maintenance data of self loading mixer

中科自上料搅拌车维修中不能科学的选择维修数据是造成机件早期损坏的重要原因。比如气门与气门座接触面的宽度，规定进气门为1-2.2mm，排气门为1.5-2.5mm，但在实际维修当中，很多人认为宽一点比窄一点要好，习惯选用上限或接近上限值，因为刚修好的车气门工作面宽度就已经接近使用极限了。

In the maintenance of Zhongke self loading mixer, the failure to select the maintenance data scientifically is an important reason for the early damage of parts. For example, the width of the contact surface between the valve and the valve seat is 1-2.2mm for the intake valve and 1.5-2.5mm for the exhaust valve. However, in actual maintenance, many people think that a wider one is better than a narrower one. They are used to choose the upper limit or close to the upper limit, because the width of the newly repaired valve working surface is close to the limit of use.

再比如气门脚间隙，一般车辆规定为0.2-0.25mm，但在维护调整中也会认为间隙大一点比小一点好，因此，超上限使用，实际上间隙过大，不但降低发动机功率，还会出现敲击声而早期损坏。

Another example is the valve foot clearance, which is generally stipulated as 0.2-0.25 mm for vehicles. However, in maintenance and adjustment, it will be considered that a larger clearance is better than a smaller one. Therefore, if the valve foot clearance is used beyond the upper limit, it will not only reduce the engine power, but also cause knock noise and early damage.

2、自上料搅拌车气门的光磨

2. Smooth grinding of valve of self loading mixer

在搅拌车的维修中，如果气门出现烧蚀、麻点及凹陷时，均应进行光磨，一般是在光磨机上进行，作业时需要注意四个问题：一是保证气门头与杆部同心，否则应先校直；二是光磨辆在能磨出完整的锥面的前提下是越小越好；三是尽量提高表面光洁度；四是气门杆端部凹陷应予以磨平。

In the maintenance of mixer truck, if the valve is ablated, pitted and sunken, it should be polished. Generally, it is carried out 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 of grinding out a complete cone, the smaller the better; third, improve the surface finish as much as possible; fourth, improve the valve stem The end depression should be ground flat.

3、自上料搅拌车气门导管的铰销

3. Hinge pin of valve guide of self feeding mixer

气门杆与气门导管配合间隙是决定气门导管使用寿命的关键，因此当更换新的气门导管时，铰销时应严格掌握好配合间隙，使用各搅拌车车型规定间隙的下限，可有效延长使用寿命。

The fit clearance between valve stem and valve guide is the key to determine the service life of valve guide. Therefore, when replacing a new valve guide, the fit clearance should be strictly controlled when hinge pin is used. The lower limit of clearance specified by each mixer can effectively prolong the service life.

4、自上料搅拌车气门的研磨

4. Grinding of valve of self loading mixer

中科自上料搅拌车气门的研磨分为两种情况：一是气门与气门座只有轻微麻点，不需要光磨和铰销时的研磨；二是气门与气门座均经过光磨和铰销后的研磨。

The grinding of the valve of Zhongke self feeding mixer can be divided into two situations: one is that the valve and valve seat only have slight pitting, which does not need grinding and hinge pin grinding; the other is that the valve and valve seat are ground after grinding and hinge pin.

前者先用足金钢砂研磨，将麻点研磨掉后，再用细金刚砂研磨，然后涂上机油研磨，直密封符合要求，宽度符合规定为止。

The former is first ground with full gold steel sand, after the pitting is ground off, then ground with fine emery, and then ground with engine oil until the seal meets the requirements and the width meets the requirements.

后者只有密封性达不到要求时才进行研磨，但操作时一定要注意，不要过分用力，严禁将气门上下敲打，否则将出现凹形砂痕，影响维修质量。

The latter can only be ground when the sealing performance fails to meet the requirements, but attention must be paid to the operation, do not use excessive force, and it is strictly forbidden to knock the valve up and down, otherwise concave sand marks will appear, which will affect the maintenance quality.

以上是关于中科自上料搅拌车发动机早期损坏的原因，希望对你能有所帮助！

The above is about the cause of early damage of Zhongke self feeding mixer engine, hope to help you!