English 
Spanish 
Share the maintenance methods of the distribution plate and some precautions during use.
The hydraulic oil used in the system is not clean or cavitation causes the plunger pump oil distribution plate to wear and bite, resulting in a mismatch between the oil distribution plate and the cylinder oil distribution surface, reduced sealing performance and leakage, resulting in insufficient pressure or flow in the hydraulic plunger pump.
The steps for repairing a hydraulic piston pumps oil distribution plate are as follows:
1. Inspect the static sealing surface
After removing the oil distribution plate, inspect the static sealing surface for defects.
If the oil distribution plate exhibits minor wear or roughening, manual grinding can be performed on a flat plate with a precision of Class 2 or higher, using a combination of rotary and linear grinding.
Apply uniform pressure to the oil distribution plate during grinding to prevent uneven grinding.
If the oil distribution plate is severely worn, burned, or has annealed yellow or black, it must be replaced.
Burning occurs when the lubricating film between the cylinder block and the oil distribution plate is disrupted, resulting in direct metal-to-metal contact and seizure, sticking, and burning.
2. Determining the Grinding Reference Surface
If both the upper and lower surfaces of the oil distribution plate have defects, after preliminary grinding, use the least damaged surface as the reference.
3. Surface Grinding
Using the least damaged surface as the reference, grind the other surface on a surface grinder.
Then, use the other surface as the reference to grind the least damaged surface.
4. Repeated Grinding and Precautions
Repeating this process one or two times will eliminate defects on the static sealing surface of the oil distribution plate.
The purpose of alternating grinding is to fundamentally eliminate any misalignment between the upper and lower surfaces and the locating outer axis, ensuring the sealing performance of the oil distribution and static sealing surfaces.
During the grinding process, avoid excessive grinding depth in one go; ≤0.01mm is ideal.
Repair steps for a hydraulic piston pumps flat oil distribution joint:
The flat oil distribution joint of a hydraulic piston pump consists of the cylinder end face and the oil distribution plate end face. Before repair, each end face must be repaired, ground, and cleaned with oil.
Before lapping the cylinder and oil distribution plate, measure the total thickness and the required thickness, then compensate for the gap on the adjustment pad.
If the oil distribution plate requires extensive lapping, reheat treat it after lapping to ensure the hardness of the hardened layer.
On a lapping platform, secure the oil distribution plate with its static sealing surface as a reference. Hold the cylinder with both hands. Apply 800# special lapping powder and lubricating oil between the cylinder end face and the oil distribution surface and lapping.
After the cylinder end face and the oil distribution plate end face sealing belt are completely ground flat, clean the two surfaces with oil again, then replace the 1200# special grinding powder and continue grinding until the sealing belt and the outer ring support belt are in full contact (you can judge based on the effect after grinding, and the inspection method is attached below). At this time, the oil distribution friction pair is repaired.
Method for checking the lapping effectiveness of a hydraulic piston pumps flat oil distribution joint:
The simplest and most straightforward inspection method is to apply red lead to one of the mating surfaces of the joint and rub it several times with the other surface. If the red lead is removed by more than 80% on both sides, the repair is successful.
Another method is to block the oil drain channel of the oil distribution plate with grease, place the oil distribution plate on a platform, and then place the cylinder block on the distribution plate. Add kerosene to the cylinder block’s plunger hole (adding kerosene between holes) and observe for four hours. If there is no kerosene leakage or cross-holes, the joint has been properly lapping.
