Because each maintenance personnel has different understanding of the excavator, there are some misunderstandings in the maintenance process. This article will explain the misunderstanding of plunger stroke allowance and water tank during maintenance, which is only for reference.
1. Do not check the plunger stroke allowance
In the test of plunger fuel injection pump, many maintenance personnel do not pay attention to checking the stroke allowance of plunger. The stroke margin of the plunger refers to the amount of upward movement of the plunger after it is pushed to the top dead center by the cam on the camshaft.
After adjusting the oil supply start time, the reason why the travel allowance should be checked is that the travel allowance of the plunger is related to the wear of the plunger and sleeve.
After the plunger and sleeve are worn, the plunger needs to move upward for a long time to start oil supply, which delays the start time of oil supply. When the adjusting bolt is screwed out or the thicker adjusting cushion block and gasket are replaced, the lowest position of the plunger moves up to reduce the stroke allowance of the plunger.
Therefore, when maintaining and debugging the fuel injection pump, first check the stroke allowance to determine whether the fuel injection pump is still allowed to be adjusted.
During inspection, the following methods shall be adopted according to different structures of fuel injection pump:
1) Rotate the camshaft, push the plunger to the top dead center, remove the oil outlet valve and valve seat, and measure with a depth vernier.
2) After the plunger is pushed to the top dead center, pry up the spring seat of the plunger spring with a screwdriver to raise the plunger to the highest point.
Then insert a thickness gauge between the lower plane of the plunger and the tappet adjusting bolt for measurement. The standard stroke allowance of the plunger is about 1.5mm, and the limit stroke allowance after wear shall not be less than 0.5mm.
2. The water tank is overheated and quench water is added
Overload operation of the engine, poor heat dissipation or lack of water in the water tank will cause overheating of the water tank. At this time, if cold water is added immediately, the cylinder head and cylinder block will burst. Therefore, in case of overheating of the water tank during use, emergency measures shall be taken to stop the operation and make the cooling water of the diesel engine cool down by itself.
