RcTek : Information & Resources for the Model Car Racer

RcTek : Radio Control Equipment Basics - Servos

This article is part of a section of the RcTek site that provides information about the radio equipment used to control model cars.

In this article we have information about the servos that are used to control the various parts of the model car.


Radio Control Servo

The servo can be considered the ‘muscle’ part of the radio control system and are responsible for the movements that control the car. They can be used to control both steering and acceleration/braking, but in some electric vehicles one of the servos is replaced in by a unit called an electronic speed controller (ESC).

Servos come in an ever-growing range of sizes and capacities. This can be a minefield as the differences between two different servos can be quite small. They all share the same basic construction though, in that a small electronically controlled electric motor generates movement of the steering, brake and throttle using a system of gears to produce the required torque and speed.

Servo Horns

Radio Control Servo Horn

The servo horn is the part that is used to connect the servo to the the rest of the control linkages and normally uses a splined recess that fits onto the output shaft of the servo. Different manufacturers use splines with different amounts of ‘teeth’ and you should always make sure that you have the correct type for your servo. Servo horns also come in many different shapes and sizes.

Servo Connectors

Radio Control Servo Plugs

The actual connecting plugs that it used on the servos also come in different types. Although there has been an effort made to standardise by some companies, you should ensure that you have the correct ones for the rest of your radio equipment.

All types of connecting plugs are designed so that they cannot be plugged in the wrong way round, but are sometimes cut by a model car owner in order to fit into a receiver from a different manufacturer.

Servo Wires

Radio Control Servo Wires

Guess what? Yes, the wires used to connect the servo also have their variations. Not only do they come in different colours but the order in which the wires are connected can also be different.

As with the servo plugs, there has been an effort made to standardise by some companies, but you can irreparably damage a servo by connecting the wires in the wrong order.


Hopefully this basic explanation of the servos used in radio controlled model cars will not have deterred you. As long as you follow a common sense view and ask for advice, the minefield of different connectors, wires and servo horns is easily avoided. Please use the links to the other items that go together to form a radio control system.

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