Engine oil is essential in the use of diesel engines, the main role is lubrication, cooling, cleaning and so on. Therefore, many small concrete mixer drivers will pay attention to check the oil quantity of the lubricating oil, and add it according to the standard, but ignore the inspection of the quality of the lubricating oil and the timely replacement of the already modified oil, resulting in the total moving parts of some engines. It operates in a poorly lubricated environment and accelerates the wear of the various components. Generally, the loss of oil is not very large under normal conditions, but it is very likely to cause pollution and lose the role of protecting the diesel engine. During the operation of the diesel engine, many pollutants (soot, coke and scale generated by the incomplete combustion of the fuel) will enter the oil. For new or overhauled machinery, there will be more impurities after the test run. If it is only used without being replaced, it will be easy to cause accidents such as burning tiles and holding shafts. In addition, even if the engine oil is replaced, some drivers will not completely clean the oil passage during the replacement due to lack of maintenance experience or trouble, so that mechanical impurities remain in the oil sump and the oil circuit.
2, the concrete shop, the car, the cylinder liner and the new piston are installed without matching
When replacing the cylinder liner and the piston, it is considered that the new cylinder liner and piston are standard parts, interchangeable, and can be used when installed. In fact, the size of the cylinder liner and the piston have a certain tolerance range. If the largest size cylinder liner is fitted with the smallest size piston, the matching clearance will be too large, resulting in compression weakness and difficulty in starting. Therefore, the small concrete mixer truck must check the size of the standard cylinder liner and the piston before the replacement. The cylinder liner and the piston must be the same as the standard cylinder size code of the standard cylinder. There is a standard fit gap between the two. In addition, when each cylinder is equipped with the same group code cylinder liner and piston, it is necessary to pay attention to the cylinder plug clearance before installation. In order to ensure the assembly standard, another inspection should be carried out before installation to prevent the counterfeit and defective products from being installed.
3 cement transport vehicles bogey do not check the plunger stroke margin
During the commissioning process of the plunger fuel injection pump, many maintenance personnel did not pay attention to checking the stroke allowance of the plunger. The stroke margin of the plunger refers to the amount of movement that can continue to move upward after the plunger is pushed from the top of the cam to the top dead center on the camshaft. After adjusting the fuel supply start time of the small concrete mixer truck, the reason for checking the stroke margin is because the stroke allowance of the plunger is related to the wear of the plunger and the sleeve. After the plunger and the sleeve are worn, the plunger must be moved upward for a period of time before the oil supply can be started, and the fuel supply start time is postponed. When the adjustment bolt is unscrewed or replaced with a thicker adjustment pad or gasket, the lowest position of the plunger moves up, reducing the stroke allowance of the plunger. Therefore, when repairing and debugging the fuel injection pump, the stroke allowance should be checked first to determine whether the fuel injection pump is still allowed to adjust. When inspecting, the following different methods should be adopted according to the different structure of the fuel injection pump: a) Rotate the camshaft, after the plunger is topped to the top dead center, remove the oil discharge valve and the valve seat, and measure with a deep vernier. b) After the plunger is pushed to the top dead center, use a screwdriver to pry the spring seat of the plunger spring to raise the plunger to the highest point. Then use a gauge to insert the measurement between the lower plane of the plunger and the tappet adjustment bolt. The standard stroke allowance of the plunger is about 1.5mm, and the limit to the limit stroke after wear should be no less than 0.5mm.
