The taboo of construction machinery maintenance—not checking the plunger stroke allowance

There are many taboos in construction machinery maintenance. This article is the 8th in this series. If you are interested in this, you can follow us.

During the commissioning of the plunger fuel injection pump, many maintenance personnel do not pay attention to check the stroke margin of the plunger (the so-called stroke margin of the plunger means that after the plunger is pushed to the top dead center by the cam on the camshaft, it can still The amount of movement that continues upward).

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.

If you need to buy a plunger pump and other accessories, CCMIE is a good choice for you. If you need to buy second-hand rollers, second-hand excavators, second-hand loaders, second-hand graders and other second-hand machinery, you can also contact us at any time!