How RC Servos Work: Servos typically control the steering in RC cars, a pretty important part of the experience. Lets take a look at how they work.

HOW THEY OPERATE

Servo Mechanisms or Servo for short, operate with a motor, gearing, and a sensor inside of them. There are almost always three wires powering them, a ground, a 6V positive, and a PWM wire which is what sends the signal. The PWM signal, which stands for (Pulse Width Modulation), sends a set of pulses to the Servo which tells it where to be positioned in relation to itself, this signal is typically given from the Receiver, with ESC playing very little, to no part in operating the Servo.

The motor that powers most servos, operates at several thousand RPM. This is significantly slowed down by the gearing inside the Servo. Servos could have a high RPM motor with a lot of gearing, making the Servo slower but have significantly more torque, some servos are set up to have a high RPM motor, with little gearing for more speed, and some servos have an extremely high RPM motor with a lot of gearing for speed and torque.

The wires will come into a chip, this chip will send the power to the motor and convert the PWM signal to another set of pulses that would command the motor to perform at a certain speed and reach a specific angle. Typically directly above this chip is the potentiometer. The potentiometer is a sensor, that is connected to a long rod that has most of the gearing attached to it. This sensor reads the angle of the gearing as the motor spins the gearing. Once the specific angle has been reached, the potentiometer communicates with the chip, the chip then communicates with the motor and shuts off the motor.

This diagram below shows where all the pieces fit into each other.

WHAT IS A SERVO HORN?

The servo horn, not like the one that makes noise is a small piece that attaches to the top of the Servo and connects it to the Steering Rack.

When a servo is being used for something other than steering the Horn may or may not be needed.

There are many different Servo horns, composite, plastic, metal, steel and more. The horns position also changes the performance of the Servo, a horn that stands high up is more responsive but less forgiving. A servo horn that is positioned lower is less responsive but more forgiving.

SO MANY DIFFERENT ONES

There are a lot of different Servos, brushed, brushless, aluminum case, plastic case, metal gearing, plastic gearing, and a lot more.

The differences between these Servos is mostly just build quality but some do offer benefits others don't. For a lot of rock crawlers, a plastic case and plastic gearing is typical because they are moving so slowly, there is very little room for error or failing parts.

To choose the servo that's best for your build, it really just depends on what you want it to do. Most servos will have their torque specifications, type of gearing, and case type listed. Take what your vehicle will be doing into consideration.

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