Rice combine harvesters are core farm machinery for large-scale rice harvesting for family farms and agricultural cooperatives. Operating in muddy paddy fields with high humidity, dense crop residues, heavy chaff and dust, rice harvesters face far harsher working conditions than dry-land grain harvesters. Long-term field operation shows that paddy field working environments easily cause common faults including track corrosion, cutter blade passivation, threshing chamber blockage, fuel circuit water ingress, circuit oxidation and hydraulic oil leakage.

According to frontline agricultural machinery maintenance experience, poorly maintained rice combines suffer frequent breakdowns during harvesting seasons, increased downtime, accelerated wear of core parts such as cutter blades, threshing drums and hydraulic pumps, higher grain loss in fields, and extra consumption costs of engine oil, diesel fuel and grease. Standardized phased maintenance can ensure harvesting efficiency, reduce grain waste, extend machine service life and cut repair and replacement costs. This guide compiles practical maintenance standards for tracked full-feed and half-feed rice combines, tailored for local farming and cross-regional harvesting operations worldwide.

1. Four-level Maintenance Standards for Rice Combines (Field Practical Standard)

Based on cross-regional harvesting and single-cropping rice field working conditions, the agricultural machinery industry divides rice harvester maintenance into four levels. Operators shall follow targeted maintenance rules to avoid excessive disassembly or omitted key maintenance steps.

1. Daily Shift Maintenance: Conducted after every 8 working hours or 50 mu harvesting work. It is a mandatory daily maintenance work focusing on cleaning, inspection, fastening and basic lubrication to guarantee normal operation the next working day.

2. Primary Maintenance: Carried out after 100 cumulative working hours or 300 mu harvesting work. Based on daily maintenance, operators need to clean filter elements, adjust tightness of belts and chains, and fine-tune working clearances.

3. Secondary Maintenance: Performed after 250 to 300 cumulative working hours or 800 mu harvesting work. As in-depth mid-season maintenance, it focuses on replacing full-machine oil and fluid, inspecting and replacing vulnerable parts, and overhauling transmission components.

4. Off-season Winter Storage Maintenance: Completed after annual harvesting work. Designed for humid climates with plum rain and humid return weather, it focuses on anti-rust treatment, waterproof protection and circuit maintenance to ensure one-click startup and fault-free operation in the next planting season.

Field Tip: Increase maintenance frequency by 20% when harvesting lodged rice, wet grain, or working in low-lying deep-water paddy fields. Extra crop residue cleaning and waterproof anti-corrosion work are required in harsh paddy conditions.

2. Daily Post-shift Maintenance: Avoid Next-day Field Breakdowns

After daily harvesting work, shut down the engine, lock the header oil cylinder, disconnect the main power supply, and wait for the threshing drum and cleaning fan to stop completely before inspection and cleaning. Never clean tangled crop residues or repair components when the machine is running. Daily maintenance covers 5 core easy-to-operate items:

2.1 Full-machine Residue Cleaning to Prevent Component Abrasion

Prioritize removing tangled rice straw and weeds on header blades, crop dividers and reel wheels. Clean rice husk, mud clods and broken straw inside the feeding trough, threshing drum, concave sieve and cleaning fan. Clean sieve gaps thoroughly after wet grain harvesting, as leftover rice grains will mildew, agglomerate and wear out sieve plates. Use low-pressure compressed air to blow dust off engine dust covers, radiator fins and air filter housings. Never flush radiator fins and electronic modules with high-pressure water guns, which will bend heat dissipation fins and cause short circuits from water ingress. Clear mud from track gaps and unclog track drain holes to prevent long-term corrosion of track rubber and iron teeth by muddy water.

2.2 Oil & Fluid Level Inspection to Eliminate Power Risks

Check engine oil level via the oil dipstick, keeping oil volume between the upper and lower scale marks. Replace emulsified and whitish engine oil immediately. Check diesel tank and hydraulic oil tank levels, and drain accumulated water from the oil-water separator every day. High humidity in paddy fields easily leads to diesel water contamination and fuel injector jamming. Inspect cooling liquid level in the water tank, and only use dedicated anti-freezing and anti-rust coolant. Do not add field river water or well water directly, which will cause scale buildup and pipeline blockage.

2.3 Fastening Inspection & Vulnerable Parts Check

Tighten loose bolts of header blades, drum teeth and frame supports loosened by field vibration. Grind slightly curled edges of movable and fixed cutter blades and divider tips. Mark and replace cracked or tooth-lost transmission belts and elongated chains in time. Inspect hydraulic pipes and joints, and fix oil leakage points caused by mud corrosion.

2.4 Targeted Lubrication Protection

Apply high-temperature waterproof lithium-based grease to header hinges, reel bearings, tensioner bearings and track idler wheels. Ordinary grease is forbidden for paddy field operation, as it will dilute and fail once contacting water.

2.5 Basic Circuit Inspection

Wipe mud and dirt off battery terminals, check the integrity of waterproof sheaths of wiring plugs, and repair damaged wire harnesses to avoid electric leakage and circuit burnout in wet paddy fields.

3. Phased Scheduled Maintenance by Working Hours

3.1 Primary Maintenance (100 Working Hours / 300 Mu)

Complete all daily maintenance procedures; clean inner and outer air filter elements, and replace inner filters directly in heavily dusty rice fields. Adjust blade clearance and reel rotating speed to match rice plant height. Tighten walking chains and conveying belts, and calibrate belt parallelism. Clean impurities inside diesel coarse filters. Check threshing drum balance and fasten loose drum teeth. Adjust cleaning sieve inclination to adapt to wet and dry grain harvesting and reduce field grain loss.

3.2 Secondary Maintenance (250-300 Working Hours / 800 Mu)

This is a critical mid-harvest maintenance node, with unified oil and fluid replacement standards for domestic and imported rice combine harvesters:

• Power System: Replace engine oil, oil filter, diesel coarse and fine filters, and full-set air filters. Test fuel injector pressure and calibrate engine idle speed to adapt to low-speed paddy harvesting;

• Hydraulic Walking System: Replace hydraulic oil, oil return filter and walking filter. Inspect sealing parts of multi-way valves and oil cylinders, and replace aging oil seals. Calibrate track tension, and replace support wheels and carrier wheels in sets when wear degree exceeds one-third;

• Threshing & Conveying System: Grind passivated cutter blades, and replace worn fixed blades and drum teeth. Adjust clearance between drum and concave plate: expand clearance for wet early rice, and narrow clearance for dry late rice. Overhaul auger bearings and grain elevator parts to avoid grain conveying jamming;

• Clutch & Brake System: Check wear thickness of clutch friction plates, adjust free travel of brake pedals to ensure safe steering on field ridges and stable startup and shutdown.

4. Off-season Storage Maintenance: Key to Next-season One-click Startup

Rice combine harvesters stay idle for 6 to 8 months every year. High humidity brought by plum rain and seasonal humid return weather in southern farming areas leads to high risks of metal corrosion, battery sulfation and fuel gum deposition. Off-season maintenance carries higher priority than in-field maintenance, with 6 standardized storage procedures:

4.1 Full-machine Deep Cleaning

Disassemble access covers to clear residual rice grains, broken straw and mud thoroughly, preventing rodent damage to parts and cavity corrosion caused by moldy grains. Rinse the whole machine with low-pressure clean water, and place it in a ventilated area for full air-drying before storage; no water residue is allowed inside machine cavities.

4.2 Fuel & Water Circuit Anti-corrosion Treatment

Drain residual diesel from fuel tanks to avoid oil oxidation and gum blockage of fuel pipelines. Empty all cooling liquid from engines and water tanks to prevent cylinder and pipe cracking in low-temperature seasons. Fill fresh engine oil, and run the engine for 3 to 5 minutes to coat inner engine walls with new oil for air isolation and anti-rust protection.

4.3 Anti-rust Treatment for Transmission & Metal Parts

Spray dedicated agricultural machinery anti-rust oil on metal working surfaces including chains, bearings, cutter blades and threshing drums. Coat exposed bolts and pin shafts with grease for water isolation. Remove all transmission belts and store them away from light; prolonged tension placement will accelerate belt aging and cracking.

4.4 Professional Battery Maintenance

Remove the storage battery, clean oxide dirt on terminals, and coat terminals with petrolatum for anti-corrosion. Store batteries indoors in dry conditions above 5℃, and conduct supplementary charging once a month to prevent plate sulfation and startup failure.

4.5 Parking & Load-bearing Protection

Store the machine indoors on elevated moisture-proof ground preferably. For outdoor parking, build rainproof sunshade shelters and cover the whole machine with dedicated dust-proof waterproof covers. Prop up the frame with wooden blocks to lift tracks completely off the ground and release long-term track pressure, preventing rubber aging and cracking. Lower and mechanically lock headers and reels to relieve long-term pressure and oil leakage of hydraulic cylinders.

4.6 Spare Parts & Maintenance Record Filing

Record model numbers of worn parts in the current harvesting season, and stock up vulnerable parts including cutter blades, filter elements, oil seals and belts. Sort out maintenance hour records to arrange targeted maintenance schedules for the next harvesting season.

5. Specialized Maintenance for Core Paddy-field Components

5.1 Track Walking System (Core Paddy Component)

Clean mud from track gaps every 50 mu of harvesting work. Reduce in-situ unilateral steering to avoid aggravated wear of track teeth. Replace leaking support wheels timely to stop muddy water entering internal bearings. Replace tracks immediately if rubber surface cracking depth exceeds 5mm to prevent mid-operation track fracture and vehicle trapping.

5.2 Threshing & Cleaning System

For full-feed combines, replace bent or broken drum teeth directly instead of grinding and reusing them, which will cause unbalanced operation and incomplete threshing. For half-feed combines, adjust tension of clamping chains to avoid rice stalk slipping and residual grain. Clean fan blade mud evenly on both sides; unilateral mud buildup will cause fan eccentric vibration and blade fracture.

5.3 Electronic Control & Waterproof System

All electronic control plugs of China Stage III / Stage IV emission compliant rice harvesters shall be equipped with waterproof sleeves. Wipe moisture off instrument panels and sensors after daily work. Do not refit circuits or add high-power electrical devices privately, which will overload and damage the on-board ECU.

5.4 Fuel System Maintenance

Use qualified agricultural diesel only for paddy field operation. Inferior low-cost diesel contains excessive impurities and water, which will block filter elements and wear fuel injectors. Drain sedimented water at the tank bottom every half month during peak harvesting periods. Seal fuel tank openings tightly on rainy days to avoid rainwater mixing into diesel fuel and cutting down fuel circuit faults fundamentally.

5.5 Header Component Maintenance

Check guard bar flatness before field operation; deformed guard bars will break cutter blades easily. Lower header height and reduce traveling speed when harvesting lodged rice to avoid hard impact on blades. Clean straw and mud between cutter blade gaps daily to ensure smooth reciprocating movement and reduce power consumption.

6. Common Maintenance Mistakes to Avoid

1. Cut off power and shut down the engine before all inspection work; never repair running drums, fans and headers;

2. Use matched lubricants and hydraulic oil only; do not mix engine oil, hydraulic fluid and grease of different grades;

3. Clean dirty filter elements first; replace broken filters directly instead of drilling holes for temporary use;

4. Check cylinder oil seals before entering paddy fields; replace seals once water seepage occurs to prevent hydraulic oil deterioration;

5. Replace vulnerable parts in advance; preventive part replacement costs far less than full machine overhaul after component failure.