Identify duty-free items via HS code

* Analysis and Identify duty-free items via HS codemaintenance of engine timing system Engine timing system refers to the geometric relationship between the engine, diesel engine and gasoline engine in the internal combustion engine, including intake valve timing, exhaust valve timing, ignition timing and fuel injection timing, etc. The timing system is crucial to the working stability and fuel economy of the engine.If there is a problem with the timing system, it will lead to engine malignation, increase fuel consumption, and reduce engine power. This article will mainly discuss the principle, analysis and maintenance methods of the engine timing system. I. The principle of timing system The engine timing system is mainly composed of geometric relationships and mechanical interfaces. The geometric relationship mainly includes the relative motion relationship of the intake valve and exhaust valve, crankshaft and camshaft, cylinder block and cylinder head, piston and cylinder block and other components. Mechanical interface mainly refers to the gear coordination of mechanical parts such as camshafts, connecting rods, crankshafts and transmission gears. The collaborative work of these components enables various throttle valves and other equipment to cooperate with each other according to the specified time in the operation of the engine, forming a system that completes fuel supply, combustion and exhaust emissions in a cycle. Specifically, the most important elements in the timing system are the crankshaft and camshaft.The crankshaft determines the simultaneous movement state of all pistons, while the camshaft determines the switching time of the intake and exhaust valves. In a four-stroke internal combustion engine, a normally compressed and burning engine needs to go through four necessary processes during the rotation of the crankshaft: intake, compression, combustion and exhaust. These operations need to be completed at the right time, or they will lead to dislocation. II. The main problem of timing system analysis of timing system is that the timing is inaccurate. There can be three types of faults in the timing system: advance, retard, jump or offset. All three faults will lead to inaccurate timing. Early timing means that the ignition time is too early, resulting in the untimely transmission of high-temperature and high-pressure gas. The fluidity of combustion products will be greatly reduced, which may lead to a decrease in engine power and unnecessary vibrations.In addition, early timing will have a considerable impact on fuel consumption. Because the engine has not completed all the strokes, the fuel is directly discarded. Backward timing means that the ignition time is too late, and the combustion efficiency of the fuel in the combustion chamber is greatly reduced, which eventually leads to a decrease in power, the acceleration ability of the vehicle is weakened, and the fuel consumption is also increased. The timing of jumping teeth/shifting includes various situations. One situation is that the gear is worn or damaged, which will cause the timing gear to no longer mesh accurately. This is usually manifested as a clicking sound when the engine is started or the engine is turned off or the engine shakes after stopping. It will also cause the engine to fail to start or turn off after starting. At this time, the faulty gears must be replaced to return to normal use. III. Time system maintenance method The maintenance of the time system needs to strictly follow the maintenance requirements and methods of the manufacturer.These are applicable to most internal combustion engines, but there are still some differences that need to be analyzed specifically. Generally speaking, the following four steps are required to repair the timing system: 1. Check and repair the gear arrangement and positioning responsible for the work of the timing system. Two. Check and replace the exhaust system or ignition system according to the requirements of the engine manufacturer. 3. Check and clean the intake and exhaust channels, and check the sealing of the piston to the cylinder block. Four. Conduct mechanical and electronic tests to ensure that all throttle valves and other equipment are working properly. Maintaining the timing system requires skills and experience, so amateur car owners are not recommended. If the owner of the car has a rotor missignment, he should contact the car repair shop for adjustment as soon as possible. In general, the engine timing system is the core component of the engine's work, and mastering the knowledge of the timing system is very important for car maintenance personnel and car owners.Only by better understanding its principle and checking and repairing faults in time can we ensure the normal operation of the car engine and extend its service life.

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