Pololu 4840/4841/4842/4843/4844/4845/4846/4847 Metal Gearmotor 25D HP 12V with 48 CPR Encoder

The Pololu 4840-4847 Metal Gearmotor 25D HP is a high-performance brushed DC motor with integrated 48 CPR quadrature encoder, designed for precision motion control in robotics and automation applications. Professional engineers and roboticists rely on this motor for closed-loop speed regulation, odometry, and accurate position tracking in mobile robots, autonomous vehicles, and industrial control systems. This product solves the critical challenge of maintaining consistent motor speed under variable load conditions while providing real-time feedback for advanced motion algorithms.

Product Overview

The Pololu 25D HP gearmotor combines a compact metal-geared transmission with a powerful 12V brushed DC motor, delivering high torque output with minimal backlash. The integrated 48 counts-per-revolution quadrature encoder provides precise rotational feedback, enabling sophisticated control strategies such as PID speed regulation and dead-reckoning navigation. The encoder outputs two 90-degree phase-shifted signals that allow determination of both motor speed and direction, making it ideal for applications requiring bidirectional motion control and accurate distance measurement.

This motor series features a robust aluminum gearbox with hardened steel gears, ensuring durability under continuous operation and high-torque demands. The 25D form factor provides an optimal balance between power density and mechanical compactness, fitting seamlessly into space-constrained robotic platforms. Multiple gear ratio variants (4840-4847) allow selection of optimal speed-torque characteristics for specific application requirements, from high-speed lightweight robots to heavy-load industrial automation systems.

Key Specifications

Specification	Details
Product Type	Metal Gearmotor with Quadrature Encoder
Brand	Pololu Robotics and Electronics
Origin	Original and Authentic
Warranty	7 days on manufacturing defects
Shipping	1-5 days from Bengaluru
Delivery	7-8 days across India
Support	24/7 via Email and WhatsApp
Motor Type	12V Brushed DC Motor
Encoder Resolution	48 CPR Quadrature Encoder
Motor Diameter	25mm
Gear Ratio Variants	Multiple ratios available (4840-4847)
Operating Voltage	12V DC

Key Features

• 48 CPR Quadrature Encoder: Provides 48 counts per motor shaft revolution with dual-channel output for precise speed measurement and directional control in closed-loop systems
• High-Torque Metal Gearbox: Hardened steel gears with minimal backlash deliver consistent torque output suitable for heavy-load robotic applications and continuous duty cycles
• Compact 25D Form Factor: Space-efficient design with 25mm diameter housing enables integration into tight robotic platforms without sacrificing performance
• Multiple Gear Ratio Options: Six variants (4840-4847) with different reduction ratios allow optimization for specific speed-torque requirements across diverse applications
• Bidirectional Control: Quadrature encoder output enables detection of motor direction and implementation of sophisticated motion algorithms including odometry and position tracking
• Robust Construction: Aluminum gearbox housing with sealed bearing design ensures durability and extended operational life under demanding industrial conditions

Applications and Use Cases

• Mobile Robot Propulsion: Drive wheels in wheeled robots with encoder feedback for accurate odometry, navigation mapping, and autonomous path planning algorithms
• Autonomous Vehicle Control: Propulsion motors in small autonomous vehicles requiring precise speed regulation and direction feedback for steering and motion control systems
• Industrial Automation: Conveyor belt drives, robotic arm joints, and positioning systems requiring consistent torque output and real-time speed feedback for process control
• Precision Motion Systems: CNC machine tool drives, 3D printer extruder mechanisms, and laboratory automation equipment requiring accurate position tracking and speed regulation
• Educational Robotics: Platform for teaching closed-loop control theory, PID algorithms, and sensor integration in university robotics laboratories and STEM programs
• Wheeled Obstacle Avoidance Robots: Encoder-based dead-reckoning for maze-solving robots and obstacle detection platforms requiring accurate distance measurement

How to Use

Begin by selecting the appropriate gear ratio variant from the 4840-4847 series based on your application's speed and torque requirements. Connect the motor leads to a 12V power supply through an appropriate motor driver circuit that can handle bidirectional control if needed. The quadrature encoder outputs two digital signals that should be connected to interrupt-capable GPIO pins or dedicated encoder input channels on your microcontroller. Configure your microcontroller to count encoder pulses using interrupt handlers, ensuring you capture both rising and falling edges on both channels to achieve maximum resolution and directional information.

Implement closed-loop speed control by reading encoder counts at regular intervals and comparing actual motor speed against your target setpoint. Use a PID controller to adjust the PWM duty cycle sent to the motor driver, compensating for load variations and ensuring consistent performance. For odometry applications, integrate encoder counts over time while tracking motor direction from the quadrature phase relationship to calculate total distance traveled and heading. Always verify encoder signal integrity with an oscilloscope before deploying in critical applications, and ensure proper debouncing if using software-based counting methods at high speeds.

Frequently Asked Questions

What is the difference between the 4840-4847 variants?

The Pololu 4840-4847 series consists of six different gear ratio variants of the same 25D HP motor. Each variant provides different speed-torque characteristics: lower-numbered models offer higher speeds with lower torque, while higher-numbered models provide lower speeds with increased torque output. Select based on your application requirements: use lower ratios for speed-critical applications like fast-moving robots, and higher ratios for heavy-load systems requiring maximum torque.

How do I implement quadrature encoder reading on a microcontroller?

Connect the two encoder output channels to interrupt-capable GPIO pins on your microcontroller. Configure external interrupts to trigger on both rising and falling edges. In your interrupt handler, read both channel states to determine rotation direction: if channels are in the same state, rotation is in one direction; if opposite, rotation is in the other direction. Count interrupts to track total rotations, with 48 counts equaling one complete motor shaft revolution. This provides both speed and directional information for closed-loop control.

What motor driver specifications do I need for this gearmotor?

Use a motor driver capable of supplying the motor's stall current at 12V, typically 1-2 amperes depending on gear ratio. The driver must support PWM input for speed control and preferably provide bidirectional control (H-bridge) for forward-reverse operation. Recommended drivers include L298N, DRV8833, or similar dual-channel drivers. Ensure the driver includes flyback diodes for back-EMF protection and thermal management for continuous operation. For applications requiring higher current capacity, use industrial-grade drivers with integrated heat sinks.

When will I receive my order?

Orders are dispatched within 1-5 business days from our Bengaluru warehouse. Delivery takes 7-8 days to most locations across India.

What is your return and warranty policy?

We offer a 7-day return policy on manufacturing defects only. Contact support within 7 days of receipt for free replacement or full refund. Not applicable for user damage or misuse.

Are bulk discounts available?

Yes, wholesale pricing for orders of 10 or more units. Contact our sales team via WhatsApp or email for a customized bulk quote.

Why Buy from The Engineer Store

• Genuine Products: Sourced directly from authorized distributors with authentication
• Expert Team: Our technical team validates every product before listing
• Fast Shipping: Dispatched within 1-5 days from our Bengaluru warehouse
• Pan-India Delivery: 7-8 days to Mumbai, Delhi, Chennai, Hyderabad, Pune, Kolkata
• Payment Options: COD, UPI, credit/debit cards, net banking, EMI available
• Technical Support: 24/7 expert guidance via email and WhatsApp
• Returns: 7-day return policy on manufacturing defects only

Buy Pololu 4840/4841/4842/4843/4844/4845/4846/4847 Metal Gearmotor 25D HP 12V with 48 CPR Encoder Online in India

Purchase the Pololu 4840/4841/4842/4843/4844/4845/4846/4847 Metal Gearmotor 25D HP 12V with 48 CPR Encoder online at The Engineer Store, India's trusted source for genuine electronics. We deliver across Bengaluru, Mumbai, Delhi, Chennai, Hyderabad, Pune, Kolkata, Ahmedabad, Jaipur, and Surat. Get the best price on Pololu 4840/4841/4842/4843/4844/4845/4846/4847 Metal Gearmotor 25D HP 12V with 48 CPR Encoder with fast shipping and expert support.

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