Digital Servos and Gyro Controllers for RC Models

Torque, speed, size and rotation range

Torque is the headline figure, given in kilogram-centimeters: a 20 kg·cm servo can hold 20 kilograms at one centimeter from the shaft, or about half that at two centimeters. Pick a rating comfortably above the load you expect. Speed, given as the time to turn through an angle, matters for steering and fast control surfaces. Digital servos update their signal faster than analog ones, so they hold position more firmly and respond more crisply.

Construction separates durable servos from toys. A coreless motor responds smoothly, metal gears resist stripping under shock, and dual ball bearings keep the output shaft steady. An IP66 rating means the case is dust-tight and protected against strong water jets, which suits boats and outdoor cars, but it does not make a servo submersible. Rotation range is a basic choice: 180-degree servos move to an angle, while 360-degree versions can turn continuously like a drive motor.

Voltage, signal and mounting: the match with your model

Check three things before the servo goes into the model. The supply voltage range in the listing must match your receiver or battery system; a servo run outside its range can overheat or stall. The control signal is normally a standard pulse-width signal on a three-wire lead, so confirm the connector fits your receiver. Finally, standard-size servos measure around 40 by 20 by 40 millimeters, which determines whether they fit the mounts.

Gyros and servo-gyro combos add stabilization. A gyro senses unwanted rotation and nudges the control to counter it, which helps a tail-heavy model or a car hold a straight line. It needs correct mounting and a setting for direction and gain, and a poorly set gyro can oscillate. Servo arms, also sold here, must match the output spline of the servo, so check the tooth count before ordering.

Questions about Digital Servos and Gyro Controllers for RC Models

What does kg·cm torque mean?

It is the turning force at a given distance from the shaft. A 20 kg·cm servo can hold 20 kilograms on a one-centimeter arm, or 10 kilograms on a two-centimeter arm. Choose a rating well above your real load so the servo is not working at its limit.

Should I choose a 180-degree or a 360-degree servo?

Choose 180 degrees when you need a position, such as steering or a control surface. A 360-degree listing may be continuous rotation, which spins like a motor with speed and direction control for wheels or winches, so read the description to see how the angle is controlled.

What does an IP66 rating mean for a servo?

The first 6 means the case is dust-tight and the second 6 means it withstands powerful water jets. It suits wet or dusty outdoor use, but IP66 does not mean the servo can be submerged. Check the seal on the output shaft and wiring entry too.