1. Adjustment of valve foot space: valve arrangement in normal operation, with the wear of parts, the valve foot space will change. If the cam, valve rod end face and tappet contact surface wear, the open space will become larger, while the valve head and valve seat wear, the open space will become smaller. Therefore, the base value of open space should be taken in the adjustment. If the rule is 0.2 ~ 0.25 mm, the actual value can be 0.22 mm. This not only takes into account the actual situation of the change of the open space, but also considers the question of the measurement error, which can fully ensure the completion of the air gap effect of the valve foot.

2、气门座的铰削：气门座铰削通常为手作业业，应格外重视三个疑问：一是在凹陷、斑驳，能铰出无缺锥面的基础上，铰削量越小越好；二是铰削时用力要均匀，起刀收刀要轻，少铰多调查，以保证较少的铰削量和较高的光洁度;三是与气门试配，判定好作业面方位和宽度。方位应调整到气门锥面的中下部，偏上或偏下可用上、下口铰刀进行调整。作业面宽度，进气门可掌握在0.9mm(规矩为1~2.2mm)，排气门可掌握在1.4mm(规矩为1.5~2.5mm)。实践证明上述宽度在气门与气门座研磨后，进气门可达1mm,排气门可达1.5mm,均在规矩宽度的下限，能大大提高其运用寿数。

2. Valve seat reaming: valve seat reaming is usually a manual operation, and three questions should be paid special attention to: first, on the basis of eliminating depression and mottling, and reaming out no missing cone surface, the smaller the reaming amount is, the better; second, the force should be even when reaming, and the knife should be lifted and closed lightly, and more investigation should be carried out to ensure less reaming amount and higher smoothness; The third is to match with the valve to determine the working face orientation and width. The orientation should be adjusted to the middle and lower part of the valve cone surface, and the upper and lower reamers can be used to adjust the position. The width of working face can be controlled within 0.9mm for inlet valve and 1.4mm for exhaust valve (1.5-2.5mm). Practice has proved that after grinding the valve and valve seat, the inlet valve can reach 1 mm and the exhaust valve can reach 1.5 mm, which are both within the lower limit of the regular width, which can greatly improve the service life of the valve.

3、搅拌车修补质量差在修补作业中出色的疑问是气门与气门座作业面加工质量达不到恳求，构成作业面烧蚀、凹陷而前期损坏；凸轮轴轴承在刮削中其协作空地、接触面积、各轴承同心度达不到恳求，加速磨损，呈现异响构成前期损坏；气门导管在更换新件时，铰削质量达不到规矩恳求，直接影响气门及气门座运用寿数。

3. The repair quality of mixer truck is poor. In the repair operation, the outstanding question is that the processing quality of valve and valve seat working surface can not meet the requirements, which constitutes ablation and depression of working surface, and early damage; camshaft bearing in scraping, its cooperation space, contact area, bearing concentricity can not meet the requirements, accelerate wear and appear abnormal noise, which constitutes early damage; when valve guide is replaced with new parts, hinge Cutting quality can not meet the requirements, which directly affects the service life of valve and valve seat.

4、凸轮轴轴承的刮削：凸轮轴轴承的刮削归于手作业业，保证质量有一定难度。为刮削便利，又通常在气缸体外加工，因此应格外留意四个疑问：一是要判定好轴承刮削后内孔的直径;二是刮削中要尽量留意坚持轴承内孔与外圆的同轴度;三是边刮削边与轴颈试配，并保证接触印痕分布均匀;四是将轴承压入座孔时，应留意对正油孔。刮削后装入凸轮轴，翻滚数圈，视情进行恰当修整，接触面积应抵达75%以上并分布均匀，空地符合规矩。

4. Scraping of camshaft bearing: scraping of camshaft bearing belongs to manual operation, so it is difficult to ensure quality. For the convenience of scraping, it is usually processed outside the cylinder. Therefore, we should pay special attention to the following four questions: first, determine the diameter of the inner hole of the bearing after scraping; second, pay attention to the coaxiality between the inner hole and the outer circle of the bearing; third, try to fit the bearing with the journal while scraping, and ensure that the contact marks are evenly distributed; fourth, when pressing the bearing into the seat hole, pay attention to aligning the oil hole. After scraping, install the camshaft, roll it for several turns, and properly trim it according to the situation. The contact area should reach more than 75% and be evenly distributed. The open space should meet the regulations.