Abstract: Dismantling has become an indispensable and primary step in repair work. Correct dismantling can reduce repair costs and improve efficiency. This paper elaborates on the principles of dismantling agricultural machinery parts, the proper use of dismantling tools, and methods for dismantling typical parts.

Currently, agricultural machinery repair in China is mainly conducted at township-level repair points. These facilities are often rudimentary, with backward technology. The primary repair method involves dismantling and replacing parts. Dismantling has thus become an essential step. While dismantling may seem simple, improper tool use, incorrect methods, and forcibly knocking parts can often expand the scope of damage, reduce repair efficiency, affect economic returns, and even introduce new potential faults. Therefore, we must emphasize the importance of dismantling agricultural machinery parts correctly, as it can extend the service life of agricultural machinery.

1. Principles of Dismantling

The dismantling of agricultural machinery must adhere to the following principles to improve work efficiency and minimize unnecessary damage.

(1) Adopt a Reasonable Dismantling Sequence: The sequence generally follows "from the exterior to the interior, disassembling step by step." That is, first remove external attachments, then dismantle the various assemblies, and finally decompose the assemblies into components and individual parts.

(2) Determine the Appropriate Level of Dismantling: The basic principle is: do not dismantle what doesn't need to be dismantled; what must be dismantled should be dismantled. If the technical condition of a component can be verified through non-dismantling inspection, it should not be dismantled. For components whose condition is uncertain without dismantling, or where preliminary inspection suggests a fault or raises suspicion, they must be disassembled for further inspection and repair.

(3) Use Suitable Dismantling Tools: Avoid rough hammering and knocking during dismantling to prevent part damage or deformation. Strive to use specialized disassembly tools to minimize part damage and enhance production efficiency.

(4) Prepare for Reassembly: Large machinery like tractors and combine harvesters have many precision-fitted parts, such as journals and bearings, or piston-connecting rod assemblies. To maintain their precise fit, mark mating parts during dismantling to ensure the original fit is restored upon reassembly. Dismantled parts should be sorted and stored accordingly.

2. Proper Use of Tools

2.1 Use of Wrenches

Wrenches are used for installing and removing bolts and nuts. Types include open-end wrenches, box-end wrenches, adjustable wrenches, socket wrenches, and torque wrenches. Precautions for their use in agricultural machinery repair dismantling are as follows:
(1) Socket wrench sets are commonly used. A socket set consists of various sized box-end sockets. Used with a ratchet handle, they allow for continuous turning and high efficiency. If workspace limitations prevent using a socket set, use box-end or open-end wrenches in sequence instead.
(2) When using an adjustable wrench, the movable jaw should bear the thrust force while the fixed jaw bears the pulling force. That is, when pulling the wrench, the movable jaw should face inward. Apply force evenly to avoid damaging the wrench or deforming the corners of the bolt/nut, which could cause slippage and accidents. Minimize the use of adjustable wrenches in repair; use box-end or socket wrenches where possible instead of double-end wrenches. Do not arbitrarily add extensions to a wrench handle, as excessive leverage can break small bolts. Also, never slip a pipe over an adjustable wrench handle to increase torque, as this can easily damage the adjustable jaws.

2.2 Lifts

Lifts include swing-arm types. When using these, ensure the arms are adjusted to be level with the vehicle and keep the arms locked during operation. For frame-contact (post/clear floor) lifts, ensure the lift pads are correctly positioned under the vehicle's designated support points, and never let them extend beyond the lift platform. Scissor lifts have the advantage of minimal space occupation, expanding for use and retracting parallel to the ground when not in use. Standard operating procedures for lifts are:
(1) Before Lifting: Clear the area around the lift of any tools or debris that might obstruct work. Check that control handles, safety locks, cables/wires, and hydraulic reservoirs are normal. Verify the load; never lift a vehicle exceeding the lift's capacity. Position the vehicle correctly. For a swing-arm lift, center the vehicle's center of gravity over the lift point, secure the arms, and after driving the vehicle onto the lift, adjust the lift pads to align precisely with the vehicle's support points.
(2) During Lifting: Operate the lift with one person. Perform a safety check and signal others before raising or lowering. Personnel should stay clear of the vehicle. Once the tires slightly lift off the ground, check if the vehicle is properly supported. Only continue lifting if everything is secure. Once at the desired height, insert the safety locks and confirm they are fully engaged before starting work underneath. Never operate the lift while someone is working under the vehicle. Do not move the vehicle or open doors while it is being lifted. Exercise caution when removing or installing large components, as this may shift the vehicle's center of gravity. If work will not be completed for some time, lower the vehicle slightly.

2.3 Hammers
Hammers should not be used indiscriminately during dismantling. When necessary, consider the material of the surface to be struck. For example, do not strike aluminum alloy parts with a steel hammer. Use aluminum, copper, or wooden mallets, or rubber hammers on precision-machined surfaces. Apply hammer blows evenly. Never strike machine surfaces directly; use a drift punch or block to avoid damaging components. Wrenches should not be used as hammers, especially adjustable wrenches which are prone to damage.

3. Dismantling Typical Parts

3.1 Threaded Connections
Threaded connections are predominant in agricultural machinery, making their dismantling a significant part of the process. While seemingly simple, improper dismantling methods can cause damage.
For dismantling bolt groups, to prevent concentrating force on a single bolt (which can make removal difficult or distort parts), first loosen all bolts alternately and diagonally by 1-2 turns each. Then remove them one by one. Start with bolts in hard-to-reach or awkward positions. For safety when dismantling cantilevered or suspended components, first support them securely with stands, blocks, jacks, or ropes. Then loosen bolts symmetrically in stages, leaving the top one or two bolts until last. Only after confirming all bolts are removed should pry bars or screwdrivers be used to separate the components at the joint face.

3.2 Interference Fit Parts
Interference fit parts present a challenge during dismantling due to their tight assembly. Avoid forcible knocking to prevent damage. Use specialized extraction tools like pullers or presses whenever possible. If unavailable, use a copper hammer or place a protective block (drift) between a steel hammer and the part's working surface. Never strike the working surface directly with a hammer. Apply force axially (along the axis of the fit).

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2025 July 1st Week FK Product Recommendation:

Plummer Block & Housing:

A plummer block housing, also known as a pillow block bearing, is a pedestal that supports a rotating shaft with the help of bearings and accessories. The housing houses the bearing, and the assembly is used in many applications, including:

· Construction machinery

· Agricultural applications

· Food and beverage processing and packaging

· Conveyor systems

· Material handling systems

· Packaging systems

· Textile equipment

· Air handling

· Special machinery, such as car wash systems, gym equipment, and go-karts

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