原文：
汽车起重机使用的75泵的修复方法： 汽车起重机采用的75泵（zb型，下同）是通过7个柱塞在缸体孔中不断地必变位置（直线运动）来吸油和压缩排油的。当柱塞磨损严重时，其与缸体孔的配合间隙就会增大，且孔径变得很不规则，使泵的压力下降，效率降低，甚至不能使用。在维修中发现，很多旧的75泵还是可以修复的。经过修复的75泵，一般都能再用2~3年。修复的方法可以避繁就简。通常情况下，液压元件的配合偶件是不能互换的，但在实际中有的 泵重新调配柱塞进行修复是可行的。就75泵来说，缸体的内也是不容易修复的，而柱塞则比较好修一些，因而可通过修复柱塞以恢复泵的功能。 修复方法有以下三种： （1）在多个废旧的75泵中寻找磨损比较小的柱塞（一组7个），然后根据柱塞和缸体也的尺寸重新配对组合，{zh1}进行研磨。 在此过程中，用外径千分尺和内径千分表多次xx测量柱塞的外径尺寸和椭圆度，以及缸体孔孔径、锥度，使所选配的柱塞和缸体孔的配合间隙达到0.02_0..4mm的要求。如此选配修复的泵一般都可以使用2年以上。 （2）当没有多余的旧泵时，可对柱塞外径和缸体孔孔径进行测量，然后将配合间隙小和磨损比较严重的分别重新组合配对。 磨损严重的柱塞可进行电镀以达到要求的尺寸（若镀层厚，可精磨至要求尺寸）；将柱塞与缸体孔配合好后，打上印记，一一研配即可。注意：电镀时，对柱塞一头的滑靴内圆球表面不要镀上。配合间隙小的且符合要求的柱塞和缸体孔可继续使用。 （3）当柱塞磨损严重时，特别是对表面有硬性伤痕的柱塞，可测绘其部尺寸并重新车制几个。车制时，要注意留出磨削余量，还要进行调质处理，比较麻根据我们的经验，对像75泵这一类价格较贵的液压元件，在不影响整机安全性能的前提下，采取少花钱、修复。

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译文：
Used truck crane 75 pump repair methods: Truck Crane with 75 pump (zb-type, the same below) is a plunger through seven holes in the cylinder will be constantly changing position (straight line) to suction and compressed row of oil. When the plunger wear serious, with the cylinder bore with the space would be increased, and the pore size becomes quite irregular, so that the pump pressure drop, efficiency, reduce, or even can not use. Found in the maintenance of many of the old 75 pump can be restored. After repair of the 75 pumps, the general could then 2 to 3 years. Repair method can avoid the simple complicated. Under normal circumstances, hydraulic components are not interchangeable with the couplings, but in practice some redeployment of the plunger pump repair is feasible. On 75 pump, the inner cylinder is not easy to repair, while the plunger is better to repair some, which can be repaired to restore the pump function of the plunger. There are three repair methods: (1) in more than 75 pumps waste to find and wear a smaller piston (a group of seven), and then under the piston and the cylinder size also re-pairs, the final grinding. In the process, with the outer diameter and inner diameter dial gauge micrometer accurate measurement of the plunger several times in size and ellipticity, as well as cylinder bore diameter, taper, so that the piston and cylinder are matching with the clearance hole achieve 0.02_0 .. 4mm requirements. Repair of the pump so matching can generally be used more than 2 years. (2) when no excess of the old pump, the piston diameter and cylinder can be measured hole diameter, and then with the clearance of small and wear more serious regrouping were paired. Severe wear can be plated plunger to the required size (if the coating thickness may be grinding to the required size); the plunger and the cylinder bore with the good, the branded mark, 11 spotting can. Note: plating, the boots on the plunger a sliding surface within the sphere do not plated. With a small gap and meet the requirements of the piston and cylinder holes can continue to use. (3) When the plunger wear serious, especially for hard surface wounds of the plunger, can the Department of Survey and Mapping of its size and try a few new vehicles system. Car system, we should pay attention to stay out of grinding margin, but also quenching and tempering treatment, compared Ma based on our experience, as 75 more expensive pump of this type of hydraulic components, machine safety, without prejudice to the premise , take less money to repair.