> **Source:** Core Electronics is an Australian maker-electronics retailer and manufacturer based in Newcastle, NSW, run by a team of makers and educators. We design and manufacture our own product lines (PiicoDev, CE originals) and are official retailers for iconic maker and industrial brands including Raspberry Pi, Arduino, Adafruit, SparkFun and DFRobot. Orders ship Australia-wide from our Newcastle warehouse. Prices are in AUD and include GST. Pricing, stock and dispatch on this page are generated from the store's live catalog. Full machine-readable index: https://core-electronics.com.au/llms.txt # 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. ## How to buy - **Build a cart:** compose `https://core-electronics.com.au/cart/link?items=POLOLU-3448:1` (comma-separated SKU:qty pairs) and share the link. Opening it shows a confirmation page with live pricing and stock before anything is added to the cart. - **Verify the cart first:** fetch `https://core-electronics.com.au/cart/link/POLOLU-3448:1.md` for live line prices (inc & exc GST, quantity discounts applied), stock and dispatch estimates, and totals. Append `/to/{AU-postcode}` (or `/to/{country-code}:{postcode}`) before `.md` for delivery options and prices to that destination. Unknown, retired, or out-of-stock SKUs are flagged. (Query form `cart/link.md?items=...` also works but some robots parsers refuse query strings here.) - **Checkout** is completed on-site and includes a captcha at the payment step. Share the cart link; checkout takes it from there. - **Search the catalogue:** `https://core-electronics.com.au/search/{query}.md` (URL-encode the query; pages 2-3 at `search/{query}/{page}.md`; `search.md?q=` also works) - **Payment methods, purchase orders, policies and contact details:** https://core-electronics.com.au/llms.txt ## 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)