Combine harvesters are core equipment for mechanized harvesting of grains, corn, rice and other crops in agricultural production. They operate in complex environments, long-term exposed to field dust, straw friction and load fluctuations, various spare parts will gradually lose their original performance due to wear, aging, fatigue and other problems. Timely replacement of failed spare parts can not only avoid equipment failure shutdown and reduce maintenance costs, but also ensure harvesting efficiency, reduce crop loss rate and extend the service life of the whole machine. Combining the working principle of combine harvesters and practical operation and maintenance experience, this article sorts out all kinds of spare parts that need regular replacement, clarifies the replacement cycle and core requirements, and provides professional reference for agricultural machinery practitioners.

I. Header System: The "Front Blade" of Harvesting Operations, the Top Priority for Wearing Parts Replacement

The header is the core component of the combine harvester that directly contacts crops, undertaking the key tasks of crop cutting and conveying. It rubs against straw, soil and stones for a long time, so the spare parts wear out quickly and it is a key area for regular replacement.

1. Cutting Components: Cutting Knives, Guards and Holders

Cutting knives are divided into moving knives and fixed knives, which are the core parts for cutting crop straw. Guards are used to fix fixed knives and protect the operation of moving knives, while holders are responsible for pressing the moving knives to ensure uniform cutting gaps. During the harvesting of wheat, rice, corn and other crops, the cutting edges of the knives will continuously rub against the straw, and may also have gaps, deformations or even breakages due to collisions with field stones and hard soil blocks. The worn cutting knives will increase the cutting resistance, which not only reduces the operation efficiency, but also leads to uneven straw cutting, affecting the subsequent conveying and threshing links.

Replacement cycle: Adjust according to the operation intensity and crop type. Wheat and rice harvesters are replaced every 1-2 harvest seasons; corn harvesters, due to thicker and harder straw, are replaced every 1 harvest season. If the cutting edge of the knife is blunted, has gaps, or the guard is deformed and the holder loses elasticity during operation, it needs to be replaced immediately without waiting for the fixed cycle. When replacing, the cutting knife bolts should be replaced together to avoid safety accidents caused by the falling off of the cutting knife due to loose bolts.

2. Conveying Components: Reel Teeth and Feeding Auger Blades

Reel teeth are responsible for pulling field crops to the cutting knife and then pulling the cut crops to the feeding auger. They are prone to bending, wear and breakage due to long-term friction with straw and impact from crops; feeding auger blades (propeller blades) undertake the task of conveying crops to the threshing system. The edges of the blades will gradually become thinner, wear out or even deform due to continuous friction with straw, resulting in reduced conveying efficiency and crop blockage.

Replacement cycle: Reel teeth are replaced every 2 harvest seasons. If the reel teeth bend more than 15° or the number of broken teeth exceeds 10% of the total, they need to be replaced in advance; feeding auger blades are replaced every 2-3 harvest seasons. If the blade thickness wears more than 30% of the original thickness, or there is obvious deformation and damage, they need to be replaced in time. When replacing, check the wear of the auger shaft. If the shaft is seriously worn, it should be replaced synchronously to avoid accelerated wear of the new blades due to shaft problems.

II. Threshing and Cleaning System: The Core of Crop Threshing and Cleaning, Spare Part Performance Determines Harvest Quality

The threshing and cleaning system is the "core hub" of the combine harvester, responsible for separating crop grains from straw and removing impurities. The spare parts of this system operate at high speed and rub against materials for a long time, prone to wear and fatigue failure, which directly affects the crop threshing rate and cleaning qualification rate.

1. Threshing Components: Threshing Drum Teeth and Concave Screens

Threshing drum teeth are the core parts of threshing, which separate grains from straw by rotating at high speed to impact and rub crops. Long-term operation will lead to wear, deformation and breakage of the drum teeth; concave screens cooperate with the drum to support crops and filter grains. The screen holes will gradually wear and become larger due to straw friction and grain impact, resulting in increased grain loss and increased impurity passing rate, affecting the cleaning quality.

Replacement cycle: Threshing drum teeth are replaced every 2-3 harvest seasons. If the drum teeth wear more than 20% of the original height, break, or the drum speed decreases, resulting in a threshing rate of less than 95%, they need to be replaced in advance; concave screens are replaced every 3-4 harvest seasons. If the screen holes wear and become larger (aperture exceeds the original standard by more than 1mm) or the screen surface is damaged, they need to be replaced in time. For corn harvesters, due to the high hardness of corn grains and thick straw, the replacement cycle of threshing components should be shortened by 10%-20%.

2. Cleaning Components: Screens and Fan Blades

Screens are divided into upper screens and lower screens, responsible for filtering impurities such as straw and broken leaves in grains. Long-term friction with grains and impurities makes the screen holes easy to block and wear, resulting in reduced cleaning effect; fan blades generate airflow by rotating at high speed to blow impurities away from grains. The edges of the blades are prone to wear and deformation due to dust and straw friction, leading to uneven airflow distribution and reduced cleaning efficiency.

Replacement cycle: Screens are replaced every 2 harvest seasons. If the screen holes are seriously blocked and cannot be cleaned, the screen surface is damaged, or the cleaning qualification rate is less than 90%, they need to be replaced in advance; fan blades are replaced every 3-4 harvest seasons. If the blades are obviously worn and deformed, or the fan has abnormal vibration during operation, they need to be replaced in time. After replacement, adjust the fan speed and screen opening to ensure the best cleaning effect.

III. Power and Transmission System: The "Power Source" of Equipment Operation, Spare Part Replacement Ensures Stable Operation

The power and transmission system provides power for the operation of various components of the combine harvester, including spare parts such as engines, transmission belts, chains and bearings. The aging and wear of these spare parts will directly lead to insufficient equipment power, failure shutdown and even safety accidents, so they must be replaced in strict accordance with the cycle.

1. Engine System: Various Filters, Engine Oil and Coolant

The engine is the "heart" of the combine harvester. The field operation environment has a large amount of dust, and impurities in air, fuel and engine oil will accelerate the internal wear of the engine. Regular replacement of filters and oil is the key to ensuring the normal operation of the engine. Among them, the air filter is responsible for filtering the air entering the engine to prevent dust from entering the cylinder; the fuel filter filters impurities in the fuel to prevent the fuel injector from being blocked; the oil filter filters metal debris and impurities in the engine oil to protect the moving parts such as the engine crankshaft and connecting rod; engine oil and coolant play a role in lubrication and cooling, and will deteriorate and their performance will decline after long-term use.

Replacement cycle: The air filter is cleaned every 50-100 hours of operation and replaced every 200 hours of operation; the fuel filter is replaced every 200-300 hours of operation; the oil filter is replaced synchronously with the engine oil every 250-300 hours of operation; the coolant is replaced every 1-2 harvest seasons. If the coolant becomes turbid and deteriorates, it needs to be replaced in advance. When replacing, select original filters and oil matching the engine model to avoid engine failures caused by mismatched parts.

2. Transmission Components: Transmission Belts, Chains and Bearings

The transmission system of the combine harvester is mainly composed of transmission belts, chains and bearings, responsible for transmitting the engine power to the header, threshing drum, walking system and other components. The transmission belt is in a tensioned state for a long time, prone to aging, cracking and slipping due to high temperature and friction; the chain is prone to wear, rust and elongation due to dust and straw friction; the bearing operates at high speed for a long time, prone to wear and ablation when lubrication is insufficient, resulting in increased operation resistance.

Replacement cycle: Transmission belts are replaced every 1-2 harvest seasons. If there are cracks, slipping and serious surface wear, they need to be replaced immediately; chains are replaced every 2 harvest seasons, and lubricating oil should be added regularly. If the chain elongation exceeds the standard, or there is rust and breakage, it needs to be replaced in advance; bearings are replaced every 3-4 harvest seasons. If there is abnormal noise and vibration during operation, or the bearing clearance is too large, they need to be replaced in time. When replacing the transmission belt, adjust the tension, and when replacing the chain, ensure that the chain meshes well with the sprocket to avoid accelerated wear.

IV. Hydraulic and Walking System: The "Support System" for Equipment Movement and Operation, Spare Part Replacement Ensures Smooth Operation

The hydraulic system is responsible for the lifting of the combine harvester header, rotation of the grain unloading cylinder, steering and other operations, and the walking system is responsible for the field movement of the equipment. The spare parts of the two systems are affected by pressure and friction for a long time, prone to aging and wear, affecting the operation flexibility and movement stability of the equipment.

1. Hydraulic System: Hydraulic Oil, Hydraulic Filters and Seals

Hydraulic oil is the working medium of the hydraulic system, responsible for transmitting pressure. It will deteriorate and be polluted after long-term use, leading to wear of hydraulic components; the hydraulic filter filters impurities in the hydraulic oil to prevent impurities from entering the hydraulic pump, hydraulic cylinder and other components; seals (sealing rings, gaskets) are responsible for sealing the hydraulic oil circuit, prone to aging and cracking due to long-term pressure and high temperature, resulting in hydraulic oil leakage.

Replacement cycle: Hydraulic oil is replaced every 250-300 hours of operation, and the hydraulic filter is replaced at the same time; seals are replaced every 2-3 harvest seasons. If hydraulic oil leakage, aging and cracking of seals are found, they need to be replaced immediately. When replacing hydraulic oil, select anti-wear hydraulic oil that meets the equipment model, and drain the air in the oil circuit after replacement to ensure the normal operation of the hydraulic system.

2. Walking System: Tires, Track Rollers and Guide Wheels (Crawler Type)

The tires of wheeled combine harvesters run on muddy and rough field roads for a long time, prone to wear, puncture and bulging; the track rollers and guide wheels of crawler combine harvesters are responsible for supporting the fuselage and guiding the operation of the crawler, prone to wear and deformation due to long-term friction with the crawler and the ground, leading to crawler deviation and increased operation resistance.

Replacement cycle: The tires of wheeled harvesters are replaced every 3-4 harvest seasons. If the tire tread wears below the safety line, bulges or punctures cannot be repaired, they need to be replaced in advance; the track rollers and guide wheels of crawler harvesters are replaced every 3-4 harvest seasons. If there is serious wear and deformation, or the crawler deviates obviously, they need to be replaced in time. When replacing tires, ensure normal tire pressure, and when replacing crawler walking parts, adjust the crawler tension to avoid accelerated crawler wear.

V. Core Precautions for Spare Part Replacement

1. Choose original spare parts: Original spare parts have high matching degree with the combine harvester model, and their material and performance meet the equipment requirements, which can effectively avoid failures caused by mismatched spare parts and extend the service life of the equipment.

2. Strictly follow the replacement cycle: The replacement cycle of different spare parts is adjusted according to the operation intensity, crop type and working conditions. Avoid waste caused by early replacement or equipment failure caused by delayed replacement. After operation, check the status of spare parts in time and make records to provide a basis for subsequent replacement.

3. Debug after replacement: After the spare parts are replaced, debug the relevant systems, such as the header cutting gap, threshing drum speed, hydraulic system pressure, walking system tension, etc., to ensure that the equipment reaches the best operation state.

4. Proper storage of spare parts: Spare parts should be stored in a dry, ventilated and dust-proof environment to avoid moisture, rust and aging. At the same time, make classified marks for quick access.

In conclusion, the regular replacement of combine harvester spare parts is the core link of equipment operation and maintenance. It is necessary to accurately control the replacement cycle and quality of spare parts around the four major systems: header, threshing and cleaning, power transmission, and hydraulic walking. Agricultural machinery practitioners should establish the operation and maintenance concept of "prevention first, regular replacement", and replace failed spare parts in time according to the actual operation of the equipment. This can not only ensure the efficient progress of harvesting operations and reduce crop losses, but also reduce the downtime of equipment failures, improve equipment utilization, and escort agricultural mechanization production.