Volumetric Accuracy in Every Drop
In the era of Smart Farming, the indiscriminate broadcasting of fertilizers is obsolete. High-value crops demand Precision Fertigation—the injection of specific nutrients directly into the irrigation water stream. The device responsible for this exacting task is the Metering Pump (Bomba Dosadora). While the fluid end (the diaphragm or piston head) handles the chemical, the Metering Pump Drive Gearbox is the brain and muscle that dictates exactly how much fluid is moved.
Unlike a standard transfer pump that moves volume simply by spinning faster, a metering drive must deliver a repeatable, pulse-free flow at high pressures. The gearbox converts the high-speed rotation of an electric motor into a slow, powerful reciprocating linear motion. Crucially, it must allow for Stroke Length Adjustment while in operation. By mechanically altering the effective stroke of the piston, farmers can vary the chemical output from 0% to 100% with micrometer precision, regardless of changes in system back-pressure.
EVER-POWER's MP-Series (Metering Power) drives are engineered to meet API 675 standards for linearity and repeatability. Utilizing advanced Variable Eccentric ou Lost Motion technologies housed in a robust cast iron or aluminum casing, these gearboxes provide the rock-solid reliability needed to inject harsh acids, caustic soda, and viscous fertilizers into irrigation lines without skipping a beat.
Technical Specifications: MP-Series (Dosing Drive)
| Parâmetro | Especificação | Parâmetro | Especificação |
|---|---|---|---|
| Potência de entrada | 0.18 kW – 7.5 kW (0.25 – 10 HP) | Stroking Speed | 30 – 180 SPM (Strokes/Min) |
| Gear Reduction | Worm (10:1 – 60:1) / Helical | Turndown Ratio | 10:1 (Standard) / 100:1 (VFD) |
| Stroke Adjustment | Manual Micrometer / Electric Servo | Accuracy | ±1% Steady State |
| Material de construção | Cast Iron / Anodized Aluminum | Max Thrust Load | 2 kN – 25 kN |
| Drive Mechanism | Variable Eccentric (ZE) / Spring Return | Lubrificação | Oil Bath Splash System |
| Interface de entrada | IEC / NEMA Flange (C-Face) | Conexão de saída | Crosshead for Piston/Diaphragm |
| Motor Voltage | 230/460V 3-Phase / 110V 1-Phase | Capacidade de óleo | 0.5L – 8.0L |
| Rolamentos | Rolo cônico reforçado | Linearity | ±3% across range |
| Vedação | Viton (FKM) / PTFE Lip Seals | Weight (Drive Only) | 15 kg – 120 kg |
| Stroke Length | 10mm – 60mm (Adjustable) | Montagem | Horizontal Foot Mount |
| Pintar | Epoxy Chem-Resist Yellow/Blue | Garantia | 24 meses |
| Compatibilidade | Milton Roy / Pulsafeeder / Seko | Aplicativo | Fertigation / pH Control / Chlorination |
Engineering the “Variable Stroke”
1. Variable Eccentricity (The “Z” Crank)
The gold standard for metering drives is the Variable Eccentric or “Polar Crank” design. In this system, the crankshaft geometry itself changes. An internal adjustment screw shifts the position of the crank pin relative to the center of rotation. This creates a true sinusoidal motion at all stroke lengths. Unlike spring-return drives, there is no “lost motion” or shock loading. The piston is mechanically pushed e pulled, making it ideal for high-viscosity fluids like molasses or polymer fertilizers.
2. Lost Motion (Spring Return)
For cost-effective applications, we utilize the Spring Return Mechanism. The gearbox drives a cam that pushes the piston forward (discharge stroke). A heavy-duty spring returns the piston (suction stroke). A mechanical stop limits how far the piston can return, effectively shortening the stroke. While simpler, this design relies on the spring force and is best suited for clear liquids and lower pressures (< 10 bar).
3. The Worm Gear Advantage
Most metering pumps utilize a Worm Gear Reduction as the primary stage. Why? Because worm gears are naturally smooth and shock-absorbing. The reciprocating action of a piston creates pulsating loads (high resistance on compression, zero on suction). A hardened steel worm driving a bronze wheel dampens these pulses, protecting the electric motor from torque spikes and ensuring quiet, vibration-free operation in the pump shed.
4. Electronic Stroke Control
Modern precision agriculture demands automation. Our gearboxes are “Smart-Ready.” The manual micrometer knob can be removed and replaced with an Electric Servo Actuator. This allows a central irrigation controller (PLC) to adjust the stroke length remotely via a 4-20mA signal. If the flow meter detects a drop in water volume, the gearbox automatically reduces the fertilizer stroke to maintain the correct ppm concentration.
Comparative Analysis: Gearbox vs. Solenoid Dosing
| Recurso | Motor-Driven Gearbox (MP Series) | Electronic Solenoid Pump |
|---|---|---|
| Capacidade | High (Up to 2000 L/hr) | Low (Typically < 20 L/hr) |
| Pressão | High (Up to 100 Bar) | Medium (Up to 10 Bar) |
| Longevity | High (Oil-bathed gears) | Medium (Electronic fatigue) |
| Viscosity | Handles Thicks Fluids | Only Thin Liquids |
| Custo | Inicial mais alto | Inicial mais baixa |
*Gearbox drives are the only viable option for commercial-scale agricultural fertigation.
Aplicação localizada: Agricultura global
Greenhouses (Netherlands/Canada)
In high-tech hydroponic glasshouses, the nutrient mix (“recipe”) changes hourly based on sunlight levels. Our Servo-Controlled Gearboxes allow the climate computer to adjust the injection rate of Potassium, Nitrogen, and Calcium independently with <1% error, maximizing yield and minimizing waste.
Broadacre (Australia/USA)
For injecting acid to treat high-pH water in pivot systems, reliability is safety. A failure can lead to equipment corrosion. Our Chem-Guard Epoxy Coated Gearboxes resist the corrosive fumes present in acid injection sheds, ensuring the drive mechanism doesn’t rust solid over the winter shutdown.
📒 Field Engineer’s Log: The “Pulsing” Pipe
“March 2026, Central Valley, California. A vineyard manager complained that his drip lines were shaking violently. He was injecting gypsum slurry.”
“We found he was using a ‘Lost Motion’ spring-return pump at high speed (120 strokes/min) to get the required volume. The rapid suction stroke was causing cavitation and water hammer (hydraulic shock) in the chemical line.
Solution: We replaced the drive with our MP-50 Variable Eccentric Gearbox geared for a slower speed (60 SPM) but with a larger piston head. The smooth, mechanically driven suction stroke of the eccentric design eliminated the cavitation. The violent pulsing stopped, and the slurry injection became smooth and consistent.”
Perguntas frequentes (OEM/B2B)
1. How often does the gearbox need oil changes?
For continuous duty applications, we recommend the first oil change after 500 hours (break-in), and then every 2,500 hours or annually. Use high-quality synthetic gear oil (ISO VG 220) to ensure the worm gear remains protected under high thrust loads.
2. Can I adjust the stroke while the pump is stopped?
It depends on the design. Lost Motion (Spring Return) drives can be adjusted while stopped. However, Variable Eccentric (ZE) drives MUST be running to adjust the stroke, as the adjustment mechanism relies on the rotation to shift the eccentric cam. Forcing it while stopped can damage the internal screw.
3. Can this gearbox handle multiple pump heads?
Yes. We offer Duplex and Triplex gearbox configurations. A single motor drives a central shaft, which powers two or three independent eccentric mechanisms. This allows you to inject two different chemicals (e.g., Acid and Fertilizer) simultaneously using one motor.
4. What happens if the discharge line is blocked?
A metering pump is a positive displacement device. If the line is blocked, pressure will build infinitely until something breaks. The gearbox is designed to withstand significant overpressure, but you MUST install an external Pressure Relief Valve on the hydraulic side to protect the motor and gearbox from catastrophic dead-head failure.
Complete Your Dosing System
Motores de lavagem
Stainless steel/Epoxy motors (TEFC) for corrosive environments.
Electric Stroke Actuators
Servo motors for remote automatic stroke adjustment (4-20mA).
Precise Growth, Measured Results
Equip your fertigation systems with EVER-POWER Metering Drives for laboratory-grade accuracy in the field.
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