Revealing The Internal Structure Of The Steering Gear: How The DC Motor + Gear Set + Control Board Work Together

Are you wondering aboutthe internal structure of theservo? To be honest, when I first came into contact with theservo, I was really curious about the mystery hidden inside when I saw that its small body could turn the angle accurately. Especially when you are doing product innovation, if you don't understand its internal structure, it's like driving without looking at the dashboard. Today we will lift off the mystery of theservoand see what capabilities it relies on to be so successful in fields such as robots and model aircraft.

What's inside the steering gear?

When it comes to the internal core configuration of the servo, it is actually like a small team that works well together. The three most critical components are the DC motor, reduction gear set and control circuit board. You can think of the DC motor as the heart, responsible for providing raw power; the reduction gear set is the skeleton, turning the power of the high-speed rotating motor into steady and powerful; the control circuit board is the brain, receiving your instructions and directing them to work. These three guys each perform their own duties and are indispensable.

Why does the motor keep turning?

Many friends may be wondering, can’t the servo only rotate at a fixed angle? Why does the motor start spinning as soon as the power is turned on? In fact, this is exactly the normal working state of the steering gear. When you send a 90-degree command to the servo, the control circuit will monitor the current position in real time. If it finds that the target has not been reached, it will let the motor continue to rotate. Just like when you drive somewhere, you must keep pressing the accelerator and drive forward until you reach your destination. The principle is the same.

What does the gear set do?

️ Here we have to talk about the beauty of the gear set. The motor itself has a very high speed and can turn tens of thousands of revolutions per minute, but its power is very small. If this high speed is directly used to control the steering wheel, it is impossible to accurately control the angle. Therefore, the gear set is used for conversion: through gear reduction step by step, high speed is turned into strong force, and at the same time, the rotation speed of the steering wheel is slowed down, so that precise positioning can be achieved. It's like a variable-speed bicycle. A low-speed gear saves effort when climbing a hill. The gear set of the steering gear has a similar idea.

How does the control circuit board know its position?

You may be wondering how the circuit board knows where to turn the steering wheel. The secret is that there is a potentiometer connected to the circuit board, and the rotating shaft of this potentiometer is linked to the final output shaft. When the steering wheel rotates, the resistance value of the potentiometer will change accordingly. By measuring this resistance value, the circuit board can calculate the current exact position. This is a very simple and reliable feedback mechanism, just like when you reach out to touch something, you know where it is when you touch it.

What should I do if the location feedback is wrong?

Sometimes the servo will vibrate or fail to turn to the designated position. This is usually due to a problem with the position feedback link. For example, the potentiometer has poor contact, or the gear is worn, resulting in inaccurate position calculation. At this time, the control circuit board will continue to issue instructions for the motor to adjust, but the balance point can never be found. In this case, you can first check whether the gear teeth are swept or listen for any abnormal noises, which can usually help you quickly locate the problem.

What should you pay attention to when disassembling the steering gear?

If you really plan to disassemble the servo and study it, be sure to be careful of the three small leads, especially the signal wires, which can be easily torn during disassembly and assembly. In addition, it is best to remember the installation sequence of the reduction gear set clearly. Installing a wrong tooth will affect the final position accuracy. It is recommended that you mark the gear before disassembling it, or take a photo, so that you have a reference when you put it back together, which saves you a long time of struggling to put it back together correctly.

Which part inside the servo do you think is most likely to fail? Welcome to share your maintenance experience in the comment area, and don’t forget to like and share it with your friends who also play with servos.