Repair of 75 pump for the hottest truck crane

Repair of 75 pump for truck crane

Guide: the 75 pump (ZB type, the same below) used by truck crane absorbs oil and compresses and discharges oil through 7 plungers constantly changing positions (linear movement) in the cylinder block hole. When the plunger is seriously worn, the fitting clearance between the plunger and the cylinder bore will increase, and the bore diameter will become very irregular, which will reduce the pressure and efficiency of the pump

the screw of 75 pump (ZB type, the same below) used by truck crane absorbs oil and compresses and discharges oil through 7 plungers constantly changing positions (linear movement) in the cylinder bore. When the plunger is seriously worn, the fitting clearance between the plunger and the cylinder block hole will increase, and the hole diameter will become very irregular, which will reduce the pressure of the pump, reduce the efficiency, and even make it unusable. During the maintenance, it was found that many old 75 pumps can still be repaired. The repaired 75 pump can generally be reused for 2-3 years. The method of repair can avoid complexity and simplify. Usually, the mating parts of hydraulic components are not interchangeable, but in practice, it is feasible for some pumps to redeploy the plunger for repair. As for 75 pump, it is not easy to repair the inside of the cylinder block, and the plunger can not interact with the packaging, so it is easier to repair, so the function of the pump can be restored by repairing the plunger. There are three repair methods:

(1) look for plungers with relatively small wear (7 in a group) in multiple used 75 pumps, then re pair and combine them according to the size of the plunger and the cylinder block, and finally grind them

in this process, use the outside micrometer and inside micrometer to accurately measure the outside diameter dimension and ovality of the plunger, as well as the bore diameter and taper of the cylinder block hole for many times, so that the matching clearance between the selected plunger and the cylinder block hole can reach 0.02_ 0 4mm. The pump so selected and repaired can generally be used for more than 2 years

(2) when there is no redundant old pump, measure the outer diameter of the plunger and the hole diameter of the cylinder block, and then reassemble the contact person: donglingyang 13718204214/Fax: 010 (6) 8669738 with small clearance and serious wear

the plunger with serious wear can be electroplated to reach the required size (if the coating is thick, it can be finely ground to the required size); After the plunger is matched with the cylinder block hole, mark it and grind it one by one. Note: during electroplating, do not coat the surface of the ball in the slipper at one end of the plunger. The plunger and cylinder block hole with small matching clearance and meeting the requirements can continue to be used

(3) when the plunger is seriously worn, especially 3. It can carry out static experiments such as uniaxial and biaxial tension of 10 shaped samples and uniaxial and biaxial compression of square samples. Especially for the plunger with hard scars on the surface, its part size can be measured and re machined

when turning, we should pay attention to leaving grinding allowance, and also carry out quenching and tempering treatment. According to our experience, for expensive hydraulic components such as 75 pump, on the premise of not affecting the safety performance of the whole machine, we can also achieve the purpose of normal use by using less money and repairing without updating