Today we will share the 9th item among the top ten taboos of construction machinery maintenance. Without further ado, let’s go straight to it.
Do not check plunger stroke allowance
During the debugging of the plunger fuel injection pump, many maintenance personnel do not pay attention to checking the stroke allowance of the plunger. The so-called stroke margin of the plunger refers to the amount of movement that the plunger can continue to move upward after being pushed to the top dead center by the cam on the camshaft. After adjusting the oil supply start time, the reason why you need to check the stroke margin is because the stroke margin of the plunger is related to the wear of the plunger and sleeve. After the plunger and sleeve are worn, the plunger has to move upward for a while before it can start oil supply, thus delaying the start of oil supply. When the adjusting bolts are unscrewed or thicker adjusting pads or gaskets are used, the lowest position of the plunger moves upward, reducing the stroke margin of the plunger. Therefore, when repairing and debugging the fuel injection pump, you should first check this stroke margin to determine whether the fuel injection pump still allows adjustment.
During inspection, the following different methods should be used according to the different structures of the fuel injection pump:
a) 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.
b) After the plunger is pushed to the top dead center, use a screwdriver to pry up the spring seat of the plunger spring to raise the plunger to the highest point.
Then use a thickness gauge to measure between the lower plane of the plunger and the tappet adjustment bolt. The standard stroke margin of the plunger is approximately 1.5mm, and the ultimate stroke margin after wear should be no less than 0.5mm.
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Post time: Jun-25-2024