The role of the China 50-1002021-A MTZ Tractor Shock absorber is : The cylinder sleeve is a cylindrical part, placed in the cylinder hole of the body, and fixed by the cylinder head. The piston makes reciprocating motion in its inner hole and cooling water is provided outside. Together with the cylinder head and piston constitute the cylinder working space

The 50-1002021-A Cylinder Liner is The functions of the are

1. Cylinder working space is formed together with cylinder head and piston.

2. Cylinder liner of cylindrical piston diesel engine bears piston side thrust and becomes the lead of reciprocating movement of piston.

3. Transfer the heat of the piston assembly and itself to the cooling water to make it work at an appropriate temperature.

4. The cylinder sleeve of two-stroke diesel engine is arranged with an air port, which is opened and closed by the piston to realize air distribution.

The inner surface of the cylinder liner is directly affected by high temperature and high pressure gas, and high-speed sliding friction always occurs with the piston ring and piston skirt. The surface is in contact with cooling water, causing severe thermal stress under large temperature difference and corrosion by cooling water. The side thrust of piston against cylinder liner not only increases the friction of inner surface, but also causes it to bend. When the side thrust changes direction, the piston also hits the cylinder liner. In addition, it is subject to greater preload of installation.

The air pressure causes the cylinder wall to produce tangential tensile stress and radial compressive stress, and the inner surface is the maximum. This stress is high-frequency pulsating stress.

The temperature difference between the inside and outside of the cylinder wall results in great thermal stress. The compressive stress is generated on the inner surface and tensile stress exists on the cooling surface at general temperature. However, under extremely high temperature, the metal on the near inner surface will creep and plastic deformation, and after cooling, the inner surface will form residual tensile stress. Such low-frequency stress caused by the changes of starting and stopping will fatigue the material.

The cylinder sleeve should have sufficient strength, stiffness and heat resistance, and should also have good abrasion resistance. There should be good lubrication and cooling in the work.

The cylinder liner is generally made of wear resistant alloy cast iron containing phosphorus or boron, such as HT25-47, HP-CucRMO, etc. The inner surface of the cylinder liner is also sometimes chrome-plated (pinhole chrome-plated, oil storage dot chrome-plated), nitride or phosphating and other treatments to improve the wear resistance. The hardness of the inner surface of cylinder liner is generally required to be greater than HB200, and it is well matched with the hardness of piston ring. The inner surface should also have proper roughness to make it have certain oil storage capacity and running-in performance. The inner surface should have sufficient roundness and cylindricity precision, and the mounting support should have high position accuracy facing the center of the inner hole.

The inner surface of the cylinder is easy to wear out due to the action of high temperature and high pressure gas and contact with the piston moving at high speed. In order to improve the wear resistance and prolong the service life of the cylinder there are different cylinder structure and surface treatment methods. There are three types of cylinder structure: cylinder liner, dry cylinder liner, wet cylinder liner.

Cylinderless casing type body is the body without any inlaid cylinder sleeve, and the cylinder is processed directly on the body. The advantage is that the center distance of the cylinder can be shortened, so that the size and mass of the body can be reduced. But the cost is higher.

The dry cylinder sleeve is not in contact with the coolant, and the wall thickness is 2~3mm. The outer surface and the inner surface of the cylinder sleeve hole must be refined to ensure the necessary positioning accuracy and facilitate disassembly. Advantages are large body stiffness, small cylinder center distance, light weight, simple processing technology. The disadvantages are poor heat transfer, uneven temperature distribution and local deformation.

The outer wall of the wet cylinder sleeve is in direct contact with the coolant, and the wall thickness is 5~8mm. Radial positioning is realized by using the upper and lower positioning belt, and axial positioning is realized by the coordination between the upper flange of the cylinder sleeve and the corresponding supporting surface on the top of the body. The advantages of wet cylinder sleeve are that there is no sealed water sleeve on the body, easy to cast, good heat transfer, more uniform temperature distribution, easy to repair, do not have to remove the engine from the car can replace the cylinder sleeve. Disadvantage is the body stiffness difference, easy to leak.

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