Continuous Rotation Servos

Continuous rotation servos are standard hobby RC servos that have been modified to offer open-loop speed control instead of their usual closed-loop position control. The modification effectively turns them into motors with integrated motor drivers in a compact, inexpensive package. Just throw on a wheel and you have a drive system for your robot that can be controlled using an RC signal or a simple direct connection to a single microcontroller I/O line. The following table shows how our continuous rotation servos compare to each other.

Continuous rotation servo size comparison. From left to right: SpringRC SM-S4303R, Power HD AR-3606HB, Parallax, and FEETECH FS90R.

SpringRC SM-S4303R PowerHD AR-3606HB Parallax (Futaba S148) FEETECH FS90R
Max Speed @ 6 V: 54 RPM 71 RPM 50 RPM 130 RPM
Stall torque @ 6 V: 71 oz-in 93 oz-in 42 oz-in 21 oz-in
Max Speed @ 4.8 V: 43 RPM 62 RPM 39 RPM 100 RPM
Stall torque@ 4.8 V: 46 oz-in 83 oz-in 33 oz-in 18 oz-in
Weight: 41 g 40 g 43 g 9 g
Size (mm): 41.3×20.7×40.2 40.5×20.0×38.0 40.5×20.0×38.0 23.2×12.5×22
Price: $12.95 $14.95 $13.95 $4.95


Pololu item #: 2149
Price: $14.95
Quantity:

The AR-3606HB is a standard-sized servo that has been built by Power HD 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. This is the fastest and strongest continuous rotation servo we carry.

Key specs at 6 V: 71 RPM (no-load), 93 oz-in (6.7 kg-cm), 40 g

Pololu item #: 1248
Price: $12.95
Quantity:

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. This is the most popular continuous rotation servo we carry.

Key specs at 6 V: 54 RPM (no-load), 71 oz-in (5.1 kg-cm), 41 g

Pololu item #: 536
Price: $13.95
Quantity:

The Parallax continuous rotation servo is a Futaba S148 servo that has been modified for continuous rotation. Since servos have their own integrated control circuitry, this unit gives you an easy way to get your robot moving.

Key specs at 6 V: 50 RPM (no-load), 38 oz-in (2.7 kg-cm), 43 g

Pololu item #: 2820
Price: $4.95
Quantity:

The FS90R is a micro servo that has been built by FEETECH (formerly known as Fitec) specifically for continuous rotation, offering an inexpensive and easy way to get your miniature robot moving or small turret spinning.

Key specs at 6 V: 130 RPM (no-load), 21 oz-in (1.5 kg-cm), 9 g