What Does an RC Car Servo do?

Servos are an electrical component used in every type of RC vehicle, from aircraft to cars, boats, and robots. These components are what animate the radio control vehicle and allow it to move, change orientation, steer or perform an action that requires movement. 

Are all RC car servos the same, or are there different types for different applications?

RC car servos are designed to animate the radio-controlled vehicle by moving certain parts in response to the signals received. In RC cars, this is generally to steer the car. Servos can be analog or digital, small, medium or large, and have linear, rotational, or continuous rotation actions.

RC car servos are generally used for steering, but they are also used for throttle control. 

How do these servos work, and are there any different types you need to be aware of to enhance the performance of your RC car?


What Does A Servo Do On An RC Car?

A servo is an electric actuator with either linear or rotational motion to move or control an aspect of the radio control car.

Servos control rudder, flaps, ailerons elevators, and other flight controls in RC aircraft. An RC car is a little less complicated from a servo point of view, having servos mostly to control the vehicle’s steering.

Servos are a relatively cheap component to manufacture, making them a reasonably inexpensive part of an RC car to upgrade or replace.

Are all RC car servos the same, or are there different types of servos you need to consider when upgrading your car or replacing parts?

Traxxas 2075R servo

What Types Of RC Car Servos Are There?

The types of servos available on the market for RC car hobbyists are generally broken down into size and the signal type and action performed.

Analog or Digital RC Car Servos

Till recently, there was only one type of servo from a communications point of view. Analog signal servos were the only option.

Recent developments have seen the appearance of servos capable of communicating via a digital signal. The higher level of control offered by the digital signal results in the popularity of digital servos increasing.

However, you cannot simply replace an analog servo with a digital servo. The electronics in the RC car need to be compatible with digital signals to control a digital servo.

Analog servos use pulse width modulation or PWM as the signal designation. By contrast, digital servos use pulse code modulation or PCM and signal designation. This is how you can tell the two signal types apart since the physical aspects of the digital and analog servos look the same.

A label on the servo will usually indicate PWM or PCM to differentiate between the two technologies.

Digital servos are preferred for modern RC cars because they are more responsive, giving faster results when they are activated. They also have smoother control allowing smaller incremental adjustments to be made by the operator.

Digital servos are also more powerful, allowing a smaller servo to move a relatively larger part than an equivalent sized analog servo.

RC Car Servo Size

The servo size in the RC car will be determined by the power required to perform the servo’s task. Larger servos have more power than smaller ones but come with the compromise of increased weight in the RC car.

The size of your RC car will also have a role to play in the size of the servo required to perform a task. Large-scale RC vehicles use heavier, more robust parts. They often include more metal components, which need an actuator with more power to perform an action.

There are 3 main general RC car servos sizes; small, medium, and large. While there is some scope to upgrade the size of a servo to achieve better control over actions in the car, you need to be aware that you will be adding weight. An over-powered servo can damage or break components.

RC Car Servo Action

There are 3 main servo action types, depending on the intended function of the servo. These 3 action types are linear, rotational, and continuous rotation actions.

The linear function servo has a push-pull action. A rotational servo rotates forward and back, and a continuous rotation servo can spin continuously, similar to an electric motor.

The type of servo action you select for your car will depend on what the servo is designed to do on the vehicle.

Linear push-pull servos are primarily used to steer an RC car. They work in conjunction with several articulated joints to provide control of the steering wheels on the car.

Servos generally work in conjunction with other moving parts to achieve the action required in the RC car. These can be cogs and gears, levers and joints, or even stiff wire components to extend the servo’s reach into the vehicle’s body.

When replacing a servo, ensure the replacement servo has compatible connection points for your associated parts.

Traxxas 2075 servo

Are RC Servos Interchangeable?

If you need to replace a servo on your RC car, do you need to buy the same brand and model for compatibility?

Some servos differ in the voltage used to power the servo. This voltage parameter must be the same as the original servo unit to ensure compatibility and that parts will not be damaged.

Most servos use a 3-wire connection method. Two wires deliver positive and negative power. The third wire acts as the control to communicate how much the servo should move.

The connector on the servo is generally a standard 3 pin connector. However, some manufacturers use proprietary plugs to keep operators using their components.

Servos with non-standard connectors will be a problem if you do not have matching connectors in your RC vehicle. It is always worth double-checking the connector type for compatibility before committing to a purchase.

If the connector is the same, there is usually no problem using a different brand servo if the voltage is the same as the servo being replaced.

Another point to check with a replacement servo is the signal type. If your car uses analog signals, you will need a PWM servo. If your RC car has a digital capability, use a PCM servo as a replacement part.

Most modern RC cars will be equipped for the digital PCM servos, and most servos on the market are digital. However, suppose you have an older model RC car. In that case, you may need to ask specifically for a PWM servo as a replacement.

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