Surplus SpringRC SM-S4303R Continuous Rotation Servo Pair (Two Servos)
These are surplus SM-S4303R standard-sized servos continuous rotation servos that we are able to offer at specially discounted pricing. They are functionally identical to our stock SM-S4303R servos except for the direction of rotation, which is reversed, and we are selling them in pairs to help differentiate them. This product is a two-pack of servos, so ordering one unit will get you two servos.
Key specs at 6 V: 54 RPM (no-load), 71 oz-in (5.1 kg-cm), 41 g, CW rotation for pulse widths above the rest point.
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These are surplus SM-S4303R standard-sized servos continuous rotation servos that we are able to offer at specially discounted pricing. They are functionally identical to our stock SM-S4303R servos except for the direction of rotation, which is reversed, and we are selling them in pairs to help differentiate them. We got them through a one-time purchase of surplus new inventory, and we 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 our item #1248 SpringRC SM-S4303R servos, which turn in the opposite direction (otherwise, they are functionally identical).
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):
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:
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-CW.
Continuous rotation servo comparison
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.
|6 V||4.8 V||Weight (g)||Size (mm)||Direction
(1ms → 2ms)
|SpringRC SM-S4303R||54||71||43||46||41||41.3 × 20.7 × 40.2||CW→CCW||$15.95|
|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||78||70||39||40.8 × 20.1 × 38.0||CW→CCW||$15.95|
|Parallax Feedback 360°||140||35||–||–||41||40.0 × 20.0 × 37.2||CW→CCW||$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|
People often buy this product together with:
|Pololu Wheel for Standard Servo Splines (25T, 5.8mm) - 70×8mm, Black, 2-Pack|
|Mounting Bracket for Standard-Size Servos|