Abstract: Maintenance of agricultural machinery is a problem that every operator and owner of agricultural machinery will face. There are many precautions to be taken when dismantling and assembling damaged parts of agricultural machinery. People without work experience can easily cause certain damage to the machinery during the replacement process, affecting the normal service life of agricultural machinery. Therefore, it is necessary to introduce some commonly used assembly, disassembly techniques, and precautions in agricultural machinery maintenance.

In recent years, China's agricultural machinery industry has developed rapidly, and many farmers' families have also purchased agricultural machinery. However, due to the harsh working environment of agricultural machinery and insufficient understanding of its maintenance during use, key components are prone to wear, aging, fracture, and deformation. When components have problems, they need to be repaired. During the process of removing damaged parts and installing new replacement parts, there are some precautions that need to be taken and some problems may occur, which may lead to mechanical failures. Therefore, in the process of maintenance, attention should be paid to proper operation and avoid mistakes. This is because the quality of assembly directly affects the performance and service life of agricultural machinery. Due to the limitations of rural reality in our country, many agricultural machinery, especially those beyond their shelf life, can only be maintained by farmers themselves or local private small repair points. Therefore, it is necessary to understand some assembly and disassembly techniques for agricultural machinery.

1. Precautions for parts replacement in agricultural machinery maintenance

(1) At present, agricultural machinery dealers in various regions will market a large number of agricultural machinery accessories, with a complete variety and a wide range of types. At the same time, there are also differences in quality. When purchasing replacement parts, it is necessary to carefully identify the quality of the purchased parts, check for processing defects or deformations, and also verify whether the fitting dimensions and specifications are consistent with the original machine parts.

(2) For purchased metal parts, the rust, product logo, certificate of conformity, etc. on the surface of the parts should be cleaned before replacement. During installation, it is also necessary to carefully compare whether the parts are suitable. Improper and deformed parts must not be used.

(3) When replacing gear parts, attention should be paid to removing the worn gear and checking the rotation of the other gear to see if there are any problems. During the replacement process, attention should be paid to checking whether the new gear operates flexibly after assembly, and whether there is excessive clearance between forward and reverse rotation. If there are problems, it is recommended to replace the gears in pairs. When replacing the belt drive, attention should be paid to the appropriate tension of the belt after replacement. If the belt is too loose, it will slip, and if it is too tight, it will affect the service life. When replacing the hydraulic cylinder liner, the sealing ring should be replaced at the same time.

(4) For the replacement of standard parts, standard parts with the same strength or better performance than the original factory standard parts should be purchased. Low grade standard parts should not be purchased at a low price to avoid safety accidents. At the same time, attention should also be paid to the material of standard parts. For externally exposed standard parts, some manufacturers may use stainless steel materials or surface oxidation treated standard parts for corrosion prevention considerations, which should be taken into account when purchasing.

(5) In the process of disassembling damaged parts, specialized standard tools should be used as much as possible to avoid damage to the standard parts and other parts used for installation, which is beneficial for the reuse of the parts. For example, for damaged telescopic devices, specialized pull-out or extrusion devices should be used, and hammers should not be used for striking to avoid damage to other mechanical components.

(6) Some specially designed parts may appear symmetrical on both sides, but in reality, they have directional requirements for installation. When installing, attention should be paid to their forward and backward directions to avoid damage to the machinery caused by incorrect installation.

2. Summary of Disassembly and Assembly Techniques for Parts

2.1 Techniques for installing bolts and other fasteners

During the tightening process of bolts, a certain amount of pre tightening force needs to be applied to ensure the reliability of the connection and prevent the bolts from loosening during use. However, the application of pre tightening force should be moderate. Excessive force can easily cause the bolts to break, while insufficient force can cause loosening. When installing bolts, try not to use a movable wrench for work. When the movable wrench cannot tighten, it will cause excessive working clearance of the wrench, which can easily cause hand injuries and deformation of the hexagonal structure of the bolt head when tightening the bolt, which is not conducive to future disassembly and assembly. When installing bolt connections, do not use an extended wrench to tighten bolts or nuts, as excessive tension may damage the bolt structure. For bearing covers used in transmission boxes and other applications, multiple bolts are often evenly distributed for fastening. During assembly, all bolts should be installed and tightened slightly, and then tightened diagonally in sequence.

2.2 Disassembly and assembly techniques for bearing components

When disassembling and assembling bearing parts, it should be noted that many bearing parts have directionality. Non professionals should remember the installation method and direction of each bearing when disassembling to avoid mechanical failure after replacement. For example, some deep groove ball bearings have single-sided sealing. If installed in reverse, it will cause debris to enter the bearing ball and cannot achieve bearing lubrication. At the same time, angular contact ball bearings, tapered roller bearings, etc. also have directional requirements. If installed in reverse, it can cause the transmission parts to be not firmly fixed, resulting in mechanical failure and damage. For the installation of bearings, it is necessary to ensure that the model is exactly the same as the original bearing, and bearings with the same diameter but different thickness cannot be used as substitutes. At the same time, after installation, the working parts should be rotated to check for any jamming or other phenomena. If there are any problems, they should be dealt with again until they rotate flexibly. After the installation of the bearing, attention should be paid to its lubrication method. For grease lubrication, file base grease should be applied in a timely manner. For closed transmission boxes, lubricating oil should be added in a timely manner.

2.3 Assembly Techniques for Torque Transmission Connections

For mechanical structures that transmit torque, attention should be paid to the rationality of the assembly of the transmission force surface during assembly. Common methods of transmitting torque include keys and splines. When replacing, it is necessary to ensure that the purchased parts are exactly the same specifications as the original parts, and different specifications of parts cannot be used for installation. If the purchased flat key thickness is too small or the outer diameter of the spline is too small, although it can be installed during assembly without causing significant clearance and vibration, due to the small contact surface of the transmission torque, it is difficult to withstand excessive torsional force and sudden impact, which can easily cause damage to the transmission structure and production accidents.

In summary, it is necessary for both farmers who own agricultural machinery and local private agricultural machinery maintenance points to have a certain level of knowledge in maintenance and assembly. Following standardized methods for maintaining agricultural machinery can greatly avoid damage caused by disassembly and assembly, which is conducive to ensuring the normal operation of the machinery.

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2025 June 2nd Week FK Product Recommendation:

Insert Bearings：

Insert bearings (SKF Y-bearings) are based on sealed deep groove ball bearings in the 62 and 63 series, but have a convex outer ring and in most cases an extended inner ring with a specific locking device, enabling quick and easy mounting onto the shaft.

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