The Brain of the Power Harrow: Why Simplicity Fails
In the heavy Терра Рокса soils of Paraná and Rio Grande do Sul, the Power Harrow (Grade Rotativa) is the supreme tool for seedbed preparation. Unlike a rotary tiller that chops soil, the power harrow stirs it vertically using a series of counter-rotating rotors. This action preserves soil structure and moisture, critical for the “Safrinha” corn season.
The heart of this machine is the Central Gearbox (Caixa Central de Velocidades). It is not just a reducer; it is a complex distribution hub. It must accept 1000 RPM from high-horsepower tractors (200HP+), split this power to the side troughs, and often drive a rear-mounted pneumatic seeder via a PTO Through-Shaft.
Standard gearboxes overheat under these dual loads. EVER-POWER’s PH-Series Central Gearboxes feature “Quick-Change” gear sets, allowing operators to physically swap internal gears in minutes to adjust rotor speed (e.g., 300 vs 400 RPM) without changing tractor throttle, ensuring optimal soil breakup without pulverization.
Technical Specifications: PH-Series (Power Harrow)
| Параметр | Спецификация | Параметр | Спецификация |
|---|---|---|---|
| Максимальная входная мощность | 120 HP – 300 HP (90-220 kW) | Input Speed (PTO) | 540 / 1000 RPM (Shiftable) |
| Gear Change System | Rear Cover “Quick-Change” Sets | Available Rotor Speeds | 193 / 245 / 310 / 360 RPM |
| Максимальный выходной крутящий момент | 4,500 Nm | Rear PTO Output | 1-3/8″ Z6 (Through Shaft) |
| Материалы для корпуса | Ковкий чугун QT500-7 | Система охлаждения | Integrated Oil Pump (Optional) |
| Входной вал | 1-3/4″ Z20 or 1-3/8″ Z21 | Side Output Shafts | Splined DIN 5480 |
| Bevel Gear Type | Spiral Gleason (Lapped/Ground) | Материал шестерни | 20CrNiMo (Case Hardened) |
| Подшипники | Heavy Duty Tapered (Timken) | Смазка | Масляная ванна (ISO VG 220) |
| Емкость нефтяного бака | 6.5 Liters – 9.0 Liters | Рабочая температура | -20°C to +110°C |
| Материал уплотнения | Viton (FKM) Double Lip | Дыхание | High Flow Filtered |
| Functionality | Splitter (1 Input -> 2 Outputs) | Shift Mechanism | Lever or Gear Swap |
| Вес (сухой) | 85 kg – 140 kg | Mounting Base | Custom OEM Flange |
| Краска | Эпоксидный синий (RAL 5005) | Гарантия | 24 месяца |
Engineering the “Splitter” Concept
1. The Torque Split Challenge
In folding power harrows (up to 6m wide), the central gearbox acts as a Splitter Box (Caixa de Distribuição). It receives 100% of the tractor’s power and must split it equally (50/50) to the left and right wing gearboxes. This requires a robust horizontal cross-shaft assembly. We use splined connections (DIN 5480) rather than keyed shafts to eliminate stress risers that cause fatigue cracks under the oscillating load of Brazilian clay soil.
2. Thermal Management in the Tropics
With input power often exceeding 250HP, the gearbox efficiency loss (approx 2%) generates significant heat (~3.7kW). In Mato Grosso’s 40°C heat, this is fatal. Our PH-Series casings are designed with deep vertical cooling ribs and an oil capacity that is 20% larger than European standards (Comer/Bondioli equivalents), acting as a massive heat sink to keep oil temperature below 95°C.
3. The “Through-Shaft” Utility
Modern Brazilian farming utilizes “Combo Seeding” (harrowing and seeding in one pass). This requires the central gearbox to have a Rear PTO Output to drive the pneumatic fan of the seeder. EVER-POWER integrates a reinforced through-shaft made of 42CrMo4 steel, capable of transmitting up to 60HP to the rear implement without twisting, even when the main harrow rotors are under full load.
4. Quick-Change Gear Logic
Soil conditions change from field to field. Wet clay needs slower rotor speeds; dry sandy soil needs high speeds. Our gearbox features a rear cover that can be removed without tools. The operator can swap the position of two spur gears (e.g., 17T/22T) to instantly change the reduction ratio. This flexibility allows the farmer to optimize fuel consumption and tillage quality on the fly.
System Comparison: Power Harrow vs. Rotary Tiller Gearboxes
| Особенность | Power Harrow Central Box (PH Series) | Rotary Tiller Central Box (RT Series) |
|---|---|---|
| Тип нагрузки | Continuous Heavy Torque + PTO Thru-put | Intermittent Shock Load |
| Регулировка скорости | Variable (Quick-Change Gears) | Fixed Ratio (Usually) |
| Выходы | 2 Side + 1 Rear (Splitter) | 1 Side Output |
| Емкость нефтяного бака | High (7-9 Liters) | Medium (3-4 Liters) |
| Приложение | Vertical Soil Mixing (Deep) | Surface Chopping |
*Analysis based on OEM requirements for 4m+ folding implements.
Localized Application: Brazil Mega-Farms
Soybean Planting (Mato Grosso)
Large folding power harrows (6m-8m) are standard. The central splitter box must synchronize the left and right wings perfectly. Our PH-Series uses precision-ground gears (DIN Class 6) to ensure zero phase lag, preventing the rotors from colliding in the center overlap zone.
Соответствие требованиям безопасности (NR-12)
The rear PTO output is a major safety hazard. EVER-POWER gearboxes come with a bolted steel cap (for when not in use) or a specific flange that accepts ISO-compliant PTO safety shields, strictly adhering to Brazil’s NR-12 worker safety laws.
📒 Field Engineer’s Log: The Sheared Shaft
“September 2025, Cascavel, Paraná. An OEM client testing a new 5-meter harrow/seeder combo reported multiple failures of the rear PTO through-shaft. The shaft was snapping clean off when the seeder fan engaged.”
“We analyzed the metallurgy. The original shaft was standard 40Cr. It was strong but brittle under the sudden torque spike of the fan clutch engaging.
Solution: We upgraded the through-shaft to 42CrMo4 (Chromium-Molybdenum) and implemented a localized induction hardening process only on the splines, leaving the shaft body tough and ductile. We also advised the farmer to use a ‘Soft-Start’ PTO engagement on the tractor. Zero failures since.”
Часто задаваемые вопросы (OEM/B2B)
1. Is the rear PTO output independent of the gear shift?
Yes. The rear PTO through-shaft runs directly from the input shaft. Changing the “Quick-Change” gears affects only the side outputs (rotor speed), not the rear PTO speed. This ensures your seeder fan speed remains constant regardless of tillage intensity.
2. Can this gearbox handle 300HP tractors?
Our PH-300 series is rated for up to 320HP input at 1000 RPM. For tractors above this range, we recommend an external oil cooling system (pump + radiator) which we can supply as a kit.
3. Are the change gears compatible with Comer/Bondioli?
We offer drop-in replacement gear sets for most major Italian gearbox brands found in Brazil. Please provide the tooth count and module, and we can match it from our stock in São Paulo.
4. What is the recommended oil change interval?
Due to the high heat generation in central splitter boxes, we recommend the first change at 50 hours, and subsequent changes every 500 hours or annually, using high-quality synthetic ISO VG 220 oil.
Complete Your Power Harrow Drivetrain
Cam Clutch PTO Shafts
Automatic torque cut-out clutches are essential for power harrows to prevent gearbox explosion on stone impact.
Wing / Trough Gearboxes
The secondary gearboxes that drive the individual rotors. We supply the complete gear train.
External Cooling Kits
12V/24V Oil Cooler radiators with circulation pumps for 24-hour operation cycles.
High-Performance Transmission for Modern Farming
From the heavy clays of Rio Grande do Sul to the vast fields of Mato Grosso, rely on EVER-POWER engineering.
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Major Markets: Brazil, Argentina, France, Germany, USA.
