Pololu 3448 Surplus SpringRC SM-S4303R Continuous Rotation Servo Pair (Two Servos)

The Pololu 3448 Surplus SpringRC SM-S4303R is a matched pair of continuous rotation servos designed for robotics, autonomous vehicles, and motion control applications requiring unlimited 360-degree rotation capability. Professional engineers and hobbyists utilize these servos for differential drive systems, wheeled robot platforms, and applications demanding synchronized bidirectional motion without mechanical stops. This servo pair solves the critical challenge of implementing continuous motion control in compact form factors while maintaining precise speed regulation and consistent torque delivery across both units.

Product Overview

The SpringRC SM-S4303R continuous rotation servo operates on a modified internal mechanism that removes the mechanical stop present in standard servos, enabling full 360-degree rotation in both directions. Unlike standard servos that respond to pulse width modulation for angular positioning, continuous rotation servos interpret PWM signals as speed and direction commands, with the neutral position (typically 1.5ms pulse) representing zero velocity, shorter pulses commanding counterclockwise rotation, and longer pulses commanding clockwise rotation. The servo maintains constant speed proportional to the deviation from neutral, making it ideal for applications requiring sustained motion without position feedback complexity.

This Pololu surplus pair consists of two matched SpringRC SM-S4303R units sourced from manufacturing overstock, ensuring identical performance characteristics and synchronized operation critical for differential drive systems. The servos feature standard 3-wire servo connectors compatible with most microcontroller platforms including Arduino, Raspberry Pi, and dedicated servo controllers. Built-in potentiometer-based speed control allows field adjustment of maximum rotation speed without firmware modifications, while the durable gearbox design provides reliable operation across extended duty cycles typical in mobile robotics applications.

Key Specifications

Specification	Details
Product Type	Continuous Rotation Servo Pair (Two Units)
Brand	SpringRC / Pololu
Model Number	SM-S4303R
Origin	Original/Authentic Surplus Stock
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
Operating Voltage	4.8V to 6.0V DC
Stall Torque	3.0 kg-cm at 5V nominal
Speed (No Load)	60 RPM at 5V nominal
Connector Type	Standard 3-pin servo connector (Signal, Power, Ground)
Gear Type	Plastic gearbox with metal output shaft
Rotation Range	Continuous 360-degree in both directions
Control Signal	PWM 50Hz standard servo signal
Dead Band	Adjustable via internal potentiometer

Key Features

• Continuous 360-Degree Rotation: Unlimited bidirectional rotation capability without mechanical stops enables differential drive implementations and continuous motion applications without firmware complexity for position reset
• Matched Pair Configuration: Two identical units with synchronized performance characteristics ensure balanced differential drive operation and predictable robot motion trajectories without individual servo calibration
• Standard Servo Protocol Compatible: PWM signal control at 50Hz frequency integrates seamlessly with Arduino, Raspberry Pi, PIC microcontrollers, and commercial servo controllers without custom interface electronics
• Speed Adjustment Potentiometer: Internal variable resistor allows field tuning of maximum rotation speed from 30 to 60 RPM without firmware modification, accommodating different robot speed requirements and load conditions
• Robust Gearbox Design: Plastic gears with reinforced metal output shaft provide reliable torque transmission for extended duty cycles typical in mobile robotics while maintaining cost-effectiveness
• Compact Form Factor: Standard servo dimensions 40.7 x 19.7 x 36.2 mm enable integration into space-constrained robot chassis designs and commercial mobile platforms

Applications and Use Cases

• Differential Drive Wheeled Robots: Two servos mounted on opposite sides drive left and right wheels independently, enabling forward, backward, and turning motion control through differential speed commands in competition robotics and educational platforms
• Autonomous Mobile Platforms: Implement continuous motion control in line-following robots, obstacle-avoidance systems, and autonomous navigation platforms requiring sustained velocity regulation without position feedback
• Robotic Arm Joint Actuation: Use as joint actuators in multi-degree-of-freedom robotic arms where continuous rotation capability enables full workspace coverage without mechanical joint limits
• Conveyor and Drive Systems: Power conveyor belts, material handling systems, and mechanical drive mechanisms requiring sustained rotational motion with speed control via standard servo signal protocol
• Surveillance Pan-Tilt Mechanisms: Implement continuous pan and tilt motion for camera platforms and sensor mounting systems requiring smooth 360-degree rotation without step-based positioning
• Educational Robotics Projects: Ideal for Arduino-based robotics courses, STEM competitions, and maker projects where continuous motion control introduces students to PWM signal interpretation and motor control principles

How to Use

Connect the servo pair to your microcontroller using standard servo connectors: Signal wire to a PWM-capable digital pin, Power wire to 5V supply, and Ground wire to common ground. Configure PWM frequency to 50Hz with 20-millisecond period. For continuous rotation control, send pulse widths around 1.5 milliseconds for neutral (zero speed), shorter pulses (1.0-1.4ms) for counterclockwise rotation with speed proportional to pulse deviation, and longer pulses (1.6-2.0ms) for clockwise rotation. Most servo libraries abstract this complexity, allowing simple commands like servo.writeMicroseconds(1300) for counterclockwise and servo.writeMicroseconds(1700) for clockwise motion. Test each servo individually to identify the exact neutral point, as manufacturing tolerances may shift the dead band slightly. Once neutral points are identified, implement differential drive logic where identical PWM values to both servos produce straight-line motion, while different values create turning trajectories.

Power the servo pair from a regulated 5V supply capable of delivering at least 1 ampere per servo during stall conditions, totaling 2 amperes minimum for the pair. Use separate power distribution from logic circuits to prevent voltage sag affecting microcontroller operation. If using battery power, employ a voltage regulator to maintain stable 5V output across the servo operating range. Adjust the internal speed potentiometer using a small screwdriver inserted through the servo case access hole to fine-tune maximum rotation speed for your specific application, typically requiring 2-3 complete turns to span the full speed range. Monitor servo temperature during continuous operation; brief thermal management may be required for sustained high-speed applications by adding small heatsinks or reducing duty cycle.

Frequently Asked Questions

What is the difference between continuous rotation and standard servos?

Standard servos respond to PWM signals by rotating to specific angles between 0 and 180 degrees, then holding that position. Continuous rotation servos remove the mechanical stop and interpret PWM signals as speed and direction commands instead. The neutral position (1.5ms) means zero speed, shorter pulses mean counterclockwise rotation at proportional speed, and longer pulses mean clockwise rotation. This enables unlimited 360-degree rotation essential for wheeled robots and conveyor systems.

Can I use these servos with Arduino?

Yes, these servos are fully compatible with Arduino boards. Use the standard Servo library or PWM output on any digital pin capable of PWM. Configure the PWM frequency to 50Hz (20ms period) and send pulse widths between 1000-2000 microseconds. The Servo library simplifies control with servo.writeMicroseconds() function. Ensure adequate power supply separate from the Arduino logic supply to prevent voltage sag.

How do I synchronize both servos for straight-line robot motion?

First, identify the neutral point for each servo by sending 1500 microseconds and observing which servo stops first. Adjust your code to compensate for any offset differences. For straight-line motion, send identical PWM values to both servos. For turning, send different values: higher value to one servo and lower to the other. Fine-tune the speed potentiometer on each servo to match their no-load speeds, ensuring balanced differential drive performance.

What power supply do these servos require?

The SpringRC SM-S4303R servos operate at 4.8V to 6.0V DC, with 5V being the nominal operating voltage. Each servo draws up to 1 ampere during stall conditions, so provide a regulated 5V supply capable of delivering at least 2 amperes for the pair. Use a separate power supply from logic circuits to prevent voltage sag affecting microcontroller operation. Battery-powered applications should employ voltage regulation to maintain stable 5V output.

Can I adjust the speed of these servos?

Yes, each servo has an internal potentiometer accessible through a small hole in the servo case. Using a small screwdriver, you can adjust the maximum rotation speed from approximately 30 to 60 RPM. Turning the potentiometer clockwise typically increases speed while counterclockwise decreases it. Make small adjustments (quarter turns) and test the servo speed before making further changes to avoid overshooting your desired speed.

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.

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Buy Pololu 3448 Surplus SpringRC SM-S4303R Continuous Rotation Servo Pair (Two Servos) Online in India

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