What is a servomotor?

There are different types of electric motors, the type that most modellers are accustomed to is the one that makes their engines move. This type of motor is known as a solenoid motor. It is a crude and basic motor that works by passing a current through a coiled wire which turns it into a magnet, in turn, the magnet turns a component inside the motor that turns a mechanism and ultimately the wheels. The more power that the controller supplies, the greater the magnetic field and the faster and further the train goes and will continue to go until power is reduced, perfect for model trains.

A servomotor is still a motor in the traditional sense (all be it a greatly refined one), but, it is controlled by circuitry that dictates the motor's actions, a servomotor can be programmed to make a series of specific movements. A servomotor's real innovation is in how it knows when a movement has been executed and the next one can begin. Rather than simply sending messages to the motor prompting that it should operate for a determined period at a certain speed whilst hoping for the best, a servomotor acquires feedback through a series of sensors that provide the unit with information regarding its component's movement and position. This accommodates very accurate tasks to be carried out.

On the factory floor and the pursuit of technological advancements this technology has been instrumental in the capabilities of automated robots, as for us modellers, we now have semaphore signals, crossing barriers and slow-speed points that move and stop themselves in just the right place! Anything that relies on an angular motion (say a quarter of a turn each way) or a linear motion (for instance a few centimetres in each direction) can be controlled by a servo.

It does make the servomotor sound a little insignificant bragging that its contribution to our world is a few barriers and signals, but, maybe that's the point, we don't have to worry about servo motors because someone else has. There are modellers out there that know how to create their own system for operating such features on their layouts and our hats are definitely firmly off to them, but the truth is we all share in the benefit of servo motors.