In the test of plunger injection pump, many maintenance personnel do not pay attention to check the travel allowance of plunger.
The travel allowance of the plunger is the amount of movement that the plunger can continue to move upward after the CAM on the camshaft reaches the TDC.
After adjusting the start time of oil supply, it is necessary to check the stroke allowance because the stroke allowance of plunger is related to the wear of plunger and sleeve.
After the plunger and sleeve wear out, the plunger has to move up a bit to start oil supply, thus delaying the start time of oil supply. When the adjusting bolt is unscrewed or the thicker adjusting block and gasket are used, the lower position of the plunger is moved up to reduce the stroke margin 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 allowed to adjust. The following is a summary of the experience of repair personnel in SINOTENG loader:
When checking, the following methods should be adopted according to the different structure of the fuel injection pump:
A) after rotating the camshaft to top the plunger to TDC, remove the oil outlet valve and seat and measure with the depth vernier.
B) after the plunger is jacked to TDC, pry the spring seat of the plunger spring with a screwdriver to make the plunger rise to a high point.
The thickness gauge is then inserted between the lower plane of the plunger and the tappet adjusting bolt. The standard stroke allowance of plunger is about 1.5mm, and the limit stroke allowance after wear should be no less than 0.5mm.