1. Improper application of maintenance data of fully automatic feeding mixer

在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，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。

The failure to scientifically select the maintenance data in the maintenance of the self-feeding mixer is an important reason for the early damage of the 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 a wider point is better than a narrower one, and are used to selecting the upper limit or close to the upper limit value, because the width of the working surface of the valve just repaired is close to the service limit, Another example is the valve foot clearance, which is generally 0.2-0.25mm for vehicles. However, in the maintenance and adjustment process, it is also considered that the clearance is larger than smaller. Therefore, when the upper limit is used, the clearance is actually too large, which will not only reduce the engine power, but also cause early damage due to knocking noise.

2、全自动上料搅拌车气门的光磨

2. Smooth grinding of valve of fully automatic feeding mixer

在自上料搅拌车的维修中，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。

During the maintenance of the self-feeding mixer truck, if the valve is ablated, pitted and dented, it should be polished. Generally, it should be done on the smooth mill. 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. The second is that the smooth grinding vehicle is as small as possible on the premise that it can grind a complete cone. Third, try to improve the surface finish. Fourth, the depression at the end of the valve stem should be polished.

3、全自动上料搅拌车气门导管的铰销

3. Hinge pin of valve guide of fully automatic 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 fitting clearance should be strictly controlled when reaming the pin, and the lower limit of the clearance specified for each mixer model can effectively extend the service life.

4、全自动上料搅拌车气门的研磨

4. Grinding of valve of fully automatic feeding mixer

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，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，涂上机油研磨，直密封符合要求，宽度符合规定为止，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 grinding of the valve of the self-feeding mixer can be divided into two situations: first, the valve and valve seat are only slightly pitted, and there is no need for smooth grinding and hinge pin grinding. The second is that the valve and valve seat are both grinded after smooth grinding and hinge pin grinding. The former is grinded with full metal steel sand first, then the pits are grinded with fine carborundum, and finally the oil is applied for grinding until the sealing meets the requirements and the width meets the requirements. The latter is grinded only when the sealing cannot meet the requirements. However, attention must be paid during operation. Do not use excessive force, and do not knock the valve up and down, otherwise concave sand marks will appear, It affects the maintenance quality.