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If you have recently bought a Traxxas RC car or are interested in getting one you may have seen that they have a servo saver and wondered what exactly that was and what it means to you. If you are wondering about that then this article is definitely for you.
Servo savers, generally, are servo horns or arms that are created to take all the impact of a large jolt to prevent your servo gear-train from stripping out. They come with a U-shaped spring inside that has the job of taking the shock. A Traxxas servo saver, just like any other servo saver, protects the gears of your steering servo from getting stripped out as it also protects your servo from impact.
Let’s assume you’re turning right on a high-speed run and the RC vehicle slides, and in the process, hits a curb or obstacle hard with the front tire. This impact will, for a moment, try to turn your wheels as it fights against the servo. This has the capacity to strip out the gears inside your servo. On most 1/10 RC trucks, for example, a servo saver is a plastic wheel with a spring inside of it that’s quite stiff. As soon as any sudden hard jolts happen, the spring lets the wheels move. It then snaps the wheels back to the proper position once they are away from the obstacle.
So, servo savers, as the name implies, generally serve to protect and save your servo from the damage all of those impacts can cause. With servo savers, you typically won’t even notice that the job is getting done until you do not actually have a servo saver. If your servo almost constantly has to take a beating, a servo saver will quickly become your best friend.
If you want to see how servos and servo savers work instead of reading about it then you will want to check out the video below.
In the rest of this article we will discuss more about exactly how servos work as well as all of the different parts of a servo that a servo saver will help protect.
How do RC servos work?
RC servos are well-known mechanisms in RC vehicles. Regardless of whether it’s a training model, a boat, a car, a plane, or helicopter, all RC vehicles would definitely have at least one servo somewhere in the construction of the vehicle.
The job of RC servos is to convert the electrical signals into polar or linear movement. The steering system of an RC car is a good example. When the control transmits a signal to the car, the signal is decoded and sent to a servo. The servo will then rotate its drive shaft for some degrees according to the signal, and this rotation is then translated into wheel steering and the wheels of the RC car will turn.
What makes these servos very handy is the fact that they have such an easy and universal way of being driven by a simple PWM circuit. Very compact and dependable, they can typically get torques from low to high, enough to move almost everything in the car.
The Parts of an RC Servo
The controller circuit
This part of the servo is its “brain.” The controller circuit is responsible for reading the input signal of the user and translating it into a motor revolution in a way that ensures the drive shaft is rotated to the desired position.
The feedback potentiometer
The potentiometer’s shaft is attached to the servo’s driveshaft. The potentiometer rotates every time the drive shaft rotates. This way, every single rotation angle of the drive shaft corresponds to a distinct resistance of the potentiometer. By reading the potentiometer’s resistance, the controller can tell the exact angle of the servo’s driveshaft.
Typically, this is a small high-speed DC motor, which has an H-bridge circuit attached to the servo’s controls.
The gearbox is responsible for driving the revolution of the motor to the drive shaft. Additionally, the RPM is substantially reduced, and the torque is increased, the torque is one of the major characteristics of RC servos.
The drive shaft
When all the above-named parts function in exact harmony, the drive shaft is rotated in an accurate correspondence to the requested angle of the user.
Factors To Consider when Purchasing an RC Servo
If you have to purchase an RC servo there are some important things to keep in ming. Each of these factors will also affect the cost.
Precision: The accurateness of the servo in translating the input signal to drive shaft position
Speed: The speed of carrying out the translation
Strength: How much torque can be gotten during rotation
Break strength: How much the servo’s drive shaft can carry without losing its position
Motion type: How the drive shaft moves; circular or linear
Size and weight: A very important consideration, especially for small planes or helicopters. Smaller servos normally have less torque.
Bearing type: Standard servos have their main shaft supported by bushings—heavy-duty servos their main shaft supported by one or two ball bearings.
Gearbox type: Commonly, nylon gears are used for the gearbox. For heavy-duty servos, metallic gears are so used. Karbonite gears, which are quite new, offer more strength than nylon gears as well as high durability even though they’re expensive. Titanium gears are the most durable and are a lot lighter than metallic gear. Hence, they can get higher speeds and torques.
Motor type: A three-pole ferrite motor is the standard motor for servos. Five poles core-less motors are used for some high-speed servos, while heavy-duty core-less motors are used for heavy-duty servos.
Based on your needs and the features of the servos you will have to choose the most appropriate servo for you, depending on how you will be using your RC vehicle.
Types of Servos
There are two types of servos: analog and digital. When it comes to user control, there’s no difference between the two types of servos, but there’s a difference in how the motor is driven by the servo controller.
An analog servo’s motor would receive a signal from the servo controller about 30 to 50 times in one second. This is the servo’s position refresh speed.
Digital servos, on the other hand, can receive the signals for position refresh rates up to 400 times in a second.
By refreshing the motor position that often, the digital servo can achieve full torque from the start of the movement and increases the servo’s holding power by up to 3 times. This also lets the digital servo have a tighter dead-band. Plus, the servo’s response is substantially increased.
Also, digital servos can be programmed for rotation direction, speed, center and endpoints, fail-safe options, and dead bandwidth adjustment. Most digital servos operate normally right out of the box and don’t need programming.
A major downside of digital servos is the fact that they’re quite expensive and demand more power from your batteries.
Servos are an important part of your Traxxas RC car or any RC car really. The servo saver will help to keep your servo working for much longer than a car that is not equipped with it.
The servo saver is especially helpful if you often find yourself driving over obstacles or often go up and down curbs or other steep hills. For most people the servo saver is something that you will absolutely want equipped on your RC car.