# Surplus SpringRC SM-S4303R Continuous Rotation Servo Pair (Two Servos) **Type:** Product page · **SKU:** POLOLU-3448 · **Brand:** [Pololu](https://core-electronics.com.au/brands/pololu-australia) **Page:** https://core-electronics.com.au/surplus-springrc-sm-s4303r-continuous-rotation-servo-pair-two-servos.html ([markdown](https://core-electronics.com.au/surplus-springrc-sm-s4303r-continuous-rotation-servo-pair-two-servos.html.md)) These are surplus SM-S4303R standard-sized servos continuous rotation servos that we are able to offer at specially discounted pricing. They are... ## Pricing - **Price:** $71.75 (inc GST) — $65.23 AUD, exc GST - **Quantity discounts:** 6+ $62.62 (exc GST) · 12+ $60.66 (exc GST) ## Availability & dispatch - In stock, ships same business day if ordered before 2PM (Australia/Sydney). - We can dispatch 1 today, and up to 140 more in 4–7 days. ## Description | [![](https://core-electronics.com.au/attachments/localcontent/0J2320_137804e62bd.jpg)](https://core-electronics.com.au/attachments/localcontent/0J2320_179653a63fe.jpg) | |---| These are **surplus** SM-S4303R standard-sized servos continuous rotation servos that Pololu are able to offer at specially discounted pricing. They are functionally identical to Pololu's stock [SM-S4303R servos](https://core-electronics.com.au/springrc-sm-s4303r-continuous-rotation-servo.html) except for the direction of rotation, which is **reversed**, and Pololu are selling them in pairs to help differentiate them. Pololu got them through a one-time purchase of surplus new inventory, and Pololu do not expect to restock them once they are sold out. This product is a **two-pack of servos**, so ordering one unit will get you two servos. These servos have been built by SpringRC specifically for continuous rotation. At 6 V, they have a maximum rotation speed of 54 RPM (no-load) and can each produce up to 71 oz-in (5.1 kg-cm) of torque. They each feature two ball bearings on the output shaft for reduced friction, and they offer easy access to their rest-point adjustment potentiometers. They can be controlled using a direct connection to a single microcontroller I/O line without any additional electronics, which makes them great actuators for beginner robotics projects. The SM-S4303R continuous rotation servo converts standard RC servo position pulses into continuous rotation speed. The default rest point is 1.5 ms, but this can be adjusted by using a small screwdriver to turn the middle-point positioner. Pulse widths above the rest point result in clockwise rotation, with speed increasing as the pulse width increases; pulse widths below the rest point result in counterclockwise rotation, with speed increasing as the pulse width decreases. **Note:** This behavior is **different** from Pololu's [item #1248 SpringRC SM-S4303R servos](https://core-electronics.com.au/springrc-sm-s4303r-continuous-rotation-servo.html), which turn in the opposite direction (otherwise, they are functionally identical). | ![](https://core-electronics.com.au/attachments/localcontent/0J4822_10439d775b2.jpg) | |---| The servo has an 11" (270 mm) lead that is terminated with a JR-style connector and includes additional servo horns and mounting hardware. The following picture shows an example of the hardware that might be included (actual hardware could vary): | ![](https://core-electronics.com.au/attachments/localcontent/0J11374_46070b1bba9.jpg) | |---| This robotics servo is compatible with Pololu's [servo controllers](https://core-electronics.com.au/breakout-boards-and-modules/motor-drivers-controllers/servo-controllers.html) and has a Futaba-compatible output shaft, which means it works with Pololu's [servo wheels](https://core-electronics.com.au/hardware/wheels.html) for standard servos (25T, 5.8 mm spline). This servo is also compatible with Pololu's [Mounting Bracket for Standard-Size Servos](https://core-electronics.com.au/mounting-bracket-for-standard-size-servos.html): | \| [![](https://core-electronics.com.au/attachments/localcontent/0J9429_260781b6772.jpg)](https://core-electronics.com.au/attachments/localcontent/0J9429_556009b7886.jpg) \| \|---\| | \| [![](https://core-electronics.com.au/attachments/localcontent/0J11375_18584a23e72.jpg)](https://core-electronics.com.au/attachments/localcontent/0J11375_32052cf0e3a.jpg) \| \|---\|---\| | |---| If you are looking for a similar servo that is capable of limited-range position control as opposed to continuous rotation speed control, consider the [FEETECH FS5106B servo](https://core-electronics.com.au/feetech-standard-servo-fs5106b.html) or [Power HD standard servo 6001HB](https://core-electronics.com.au/power-hd-standard-servo-6001hb.html), which have comparable size, weight, speed, and torque. **Note:** The spline on this servo is slightly bigger than on Pololu's other [continuous rotation servos](https://core-electronics.com.au/components/motors/servos/continuous-rotation-servos.html), so some servo horns and wheels might have a tight fit. If you find it difficult to push a compatible servo horn or wheel on by hand, please try the installation method shown in the video below. Similarly, the servo’s mounting tabs are a tight fit with Pololu's [mounting bracket](https://core-electronics.com.au/mounting-bracket-for-standard-size-servos.html), so you might consider filing them or the mounting bracket down a little if you want to use them together. Note that, as with most hobby servos, stalling or back-driving this servo can damage it. **Note:** This servo is SpringRC part number SM-S4303R-CW. **Continuous rotation servo comparison** [![](https://core-electronics.com.au/attachments/localcontent/0J5406_2508732d798.jpg)](https://core-electronics.com.au/attachments/localcontent/0J5406_15837f1c99f.jpg) | | **6V** | **4.8V** | **Weight (g)** | Size (mm)** | Direction** **vs pulse** **(1ms → 2ms)** | Digital?** | Feedback?** | |---|---|---|---|---|---|---|---| | **Max Speed (RPM)** | **Stall Torque (oz-in)** | **Max Speed (RPM)** | **Stall Torque (oz-in)** | | **SpringRC SM-S4303R** | 54 | 71 | 43 | 46 | 41 | 41.3 × 20.7 × 40.2 | CCW?CW | | | | **Parallax Feedback 360°** | 140 | 35 | – | – | 41 | 40.0 × 20.0 × 37.2 | CW?CCW | ![yes](https://core-electronics.com.au/attachments/localcontent/check-fa31fa0963023302eb66fe206c0d1e8cb1135facdac9a4e8f5b5ffcc3c3ea377_29454a38f.png) | ![yes](https://core-electronics.com.au/attachments/localcontent/check-fa31fa0963023302eb66fe206c0d1e8cb1135facdac9a4e8f5b5ffcc3c3ea377_29454a38f.png) | | **FEETECH FS90R** | 130 | 21 | 100 | 18 | 9 | 22.5 × 12.1 × 23.4 | CW?CCW | | | **People often buy this product together with:** | [![Mounting Bracket for Standard-Size Servos](https://core-electronics.com.au/attachments/localcontent/0J9423_25402a1f2f.jpg)](https://core-electronics.com.au/mounting-bracket-for-standard-size-servos.html) | [Mounting Bracket for Standard-Size Servos](https://core-electronics.com.au/mounting-bracket-for-standard-size-servos.html) | |---|---| | [![Pololu Wheel for Standard Servo Splines (25T, 5.8mm) - 70×8mm, Black, 2-Pack](https://core-electronics.com.au/attachments/localcontent/0J10767_3570db632e.jpg)](https://core-electronics.com.au/pololu-wheel-for-standard-servo-splines-25t-5-8mm-70-8mm-black-2-pack.html) | [Pololu Wheel for Standard Servo Splines (25T, 5.8mm) - 70×8mm, Black, 2-Pack](https://core-electronics.com.au/pololu-wheel-for-standard-servo-splines-25t-5-8mm-70-8mm-black-2-pack.html) | |---|---| **Dimensions** | Size: | 41.3 × 20.7 × 40.2 mm | |---|---| | Weight: | 41 g | **General specifications** | Digital?: | N | |---|---| | Speed @ 6V: | 54 rpm | | Stall torque @ 6V: | 71 oz·in | | Speed @ 4.8V: | 43 rpm | | Stall torque @ 4.8V: | 46 oz·in | | Hardware included?: | Y | | Lead length: | 11 in | ## Images - [Product image 1](https://core-electronics.com.au/media/catalog/product/i/m/image_11979.jpg)