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Pololu item #:
1248
Brand:
SpringRC
The SM-S4303R is a standard-sized servo that has been built by SpringRC specifically for continuous rotation, making it an easy way to get your robot moving. It features two ball bearings on the output shaft for reduced friction, and it offers easy access to the rest-point adjustment potentiometer.
Key specs at 6 V: 54 RPM (no-load), 71 oz-in (5.1 kg-cm), 41 g, CCW rotation for pulse widths above the rest point.
Compare all products in Continuous Rotation Servos.
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SpringRC SM-S4303R continuous rotation servo. |
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SpringRC SM-S4303R continuous rotation servo with a US quarter for size reference. |
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An example of hardware included with the SpringRC SM-S4303R continuous rotation servo. Actual hardware might vary. |
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SpringRC SM-S4303R continuous rotation servo dimensions and technical specifications (subject to change without notice). |
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The servo cable is terminated with a Futaba-compatible JR-style connector. |
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Compatible servo wheels are available separately for the SpringRC SM-S4303R Continuous Rotation Servo. |
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Compatible servo wheels are available separately for the SpringRC SM-S4303R Continuous Rotation Servo. |
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Continuous rotation servo size comparison. From left to right: SpringRC SM-S4303R, Power HD AR-3606HB, FEETECH FS5106R, Parallax Feedback 360°, Parallax (Futaba S148), and FEETECH FS90R. |
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Surplus units available: We have made a one-time purchase of surplus new SM-S4303R continuous rotation servos that we are able to offer at specially discounted pricing. They are functionally identical this stock SM-S4303R servo except for the direction of rotation, which is reversed, and we are selling them as pairs under a different product number (item #3448) to differentiate them. Please consider them as discounted alternatives to the our stock item #1248 servos while supplies last.
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The SM-S4303R is a standard-sized servo that has been built by SpringRC specifically for continuous rotation. At 6 V, it has a maximum rotation speed of 54 RPM (no-load) and can produce up to 71 oz-in (5.1 kg-cm) of torque. It features two ball bearings on the output shaft for reduced friction, and it offers easy access to the rest-point adjustment potentiometer. The servo can be controlled using a direct connection to a single microcontroller I/O line without any additional electronics, which makes it a great actuator 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 counterclockwise rotation, with speed increasing as the pulse width increases; pulse widths below the rest point result in clockwise rotation, with speed increasing as the pulse width decreases.
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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):
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This robotics servo is compatible with our servo controllers and has a Futaba-compatible output shaft, which means it works with our servo wheels for standard servos (25T, 5.8 mm spline). This servo is also compatible with our Mounting Bracket for Standard-Size Servos:
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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 or Power HD standard servo 6001HB, which have comparable size, weight, speed, and torque.
Note: The spline on this servo is slightly bigger than on our other continuous rotation servos, 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 our mounting bracket, 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-CCW.
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Continuous rotation servo size comparison. From left to right: SpringRC SM-S4303R, Power HD AR-3606HB, FEETECH FS5106R, Parallax Feedback 360°, Parallax (Futaba S148), and FEETECH FS90R. |
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| 6 V | 4.8 V | Weight (g) | Size (mm) | Direction vs pulse (1ms → 2ms) |
Digital? | Feedback? | Price | |||
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| Max speed (RPM) |
Stall torque (oz·in) |
Max speed (RPM) |
Stall torque (oz·in) |
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| SpringRC SM-S4303R | 54 | 71 | 43 | 46 | 41 | 41.3 × 20.7 × 40.2 | CW→CCW | $14.95 | ||
| SURPLUS SpringRC SM-S4303R 2-Pack | 54 | 71 | 43 | 46 | 41 | 41.3 × 20.7 × 40.2 | CCW→CW | $19.95 for a pair of servos | ||
| FEETECH FS5106R | 95 | 83 | 75 | 67 | 43 | 40.8 × 20.1 × 38.0 | CW→CCW | $15.95 | ||
| Parallax Feedback 360° | 140 | 35 | – | – | 41 | 40.0 × 20.0 × 37.2 | CW→CCW |  |
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$27.99 |
| FEETECH FT90R | 135 | 21 | 108 | 18 | 9 | 22.9 × 12.1 × 26.5 | CW→CCW | |
$8.95 | |
| FEETECH FS90R | 130 | 21 | 100 | 18 | 9 | 22.5 × 12.1 × 23.4 | CW→CCW | $5.95 | ||
| Size: | 41.3 × 20.7 × 40.2 mm |
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| Weight: | 41 g |
| Digital?: | N |
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| 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 |
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Most standard radio control (RC) servos have three wires, each a different color. Usually, they are either black, red, and white, or they are brown, red, and orange/yellow:
Please check the specs for your servo to determine the proper power supply voltage, and please take care to plug the servo into your device in the proper orientation (plugging it in backwards could break the servo or your device).
Note: Some of the servos we carry also have an optional fourth green wire that is separate from the three standard ones. This wire provides access to the feedback potentiometer, allowing you to directly measure the position of the output. The servos with this extra wire have "with Position Feedback" at the ends of their product names. The picture below is an example of such a servo.
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FEETECH Sub-Micro Servo FS0403-FB with Position Feedback. |
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SpringRC SM-S4303R Continuous Rotation Servo Pair. We are now offering a two-pack of Surplus SpringRC SM-S4303R Continuous Rotation Servos. These...
We are thrilled to announce the release of our wheels for micro and standard sized servos. These wheels are similar to our wheels for 3mm D shafts...
Khan Academy user mbbackus created a demo that allows users to visualize the effects of sending different pulse widths to the SM-S4303R and Parallax...
