DC gear motor is widely used in electric screwdrivers. And the electric screwdriver has made people more efficient in ordinary home life, becoming invaluable for light tasks such as assembling furniture, removing battery or socket covers, hanging picture frames, or tightening loose cabinet hinges. Allows you to quickly drive and remove fasteners at the touch of a button, providing the automatic function of the electric drill.   With some special scenarios such as dental surgery, precision equipment assembly, etc., you need strong stability, more sophisticated screwdrivers. We will attach a clutch to the screwdriver, and will design a brushless gear motor or a brushed gear motor into it. This depends on the customer’s lifetime requirements for the DC gear motor.

First of all, we need to choose the appropriate DC gearmotor according to the customer’s requirements such as size, speed, and stall torque. We have brushed gear motor and brushless gear motor. Diameters range from 10-30mm, and the 13mm and 16mm are commonly used in this screw. Brushless gearbox with different gear ratios and materials can achieve a good effect of speed reduction and increasing torque.

Brushless gear motor and Brushed gear motor

Below shows how the locking clutch works

Generally speaking, the clutch device of the electric screwdriver is composed of a toothed clutch, a pressure spring, a adjusting nut and a spindle for clamping the screwdriver head.

The rotating motion of the screwdriver head is decelerated by the motor by two gears, driving the hollow shaft to rotate, the front end of the hollow shaft is the active part of the tooth clutch, after the motor starts, the hollow shaft rotates no load, and the screwdriver head is stationary. When the screwdriver head is subjected to axial pressure, the hollow shaft spring is compressed, so that the teeth of the end face of the clutch follower engage with the teeth of the clutch driver at the front end of the hollow shaft, so that the steel ball of the tooth embedded clutch makes the spindle rotate unidirectional. The spindle is integrated with the shaft pin and the screwdriver head, and the screwdriver head is also rotated together to tighten or remove the screws.

After the tooth clutch is engaged, the torque is transmitted by the three steel balls in the middle. When working, if the required torque is reached or the torque is too large, the tooth clutch follower will compress the spring, and the active part and the follower of the tooth clutch will be removed from the skid to prevent damage to the thread and motor overload.

The adjusting nut is used to adjust the output torque of the screwdriver head. Through the working spring, the clamping force of the follower of the dental clutch is adjusted to ensure that the dental clutch can be separated smoothly under a certain torque. The amount of torque can be reached by turning the adjusting nut. If the adjusting nut rotates in the direction of the tooth clutch, the spring is compressed and the torque is large; If the adjusting nut rotates in the opposite direction of the tooth clutch, the spring has a small force and the transmitted torque is also small.

This is the working principle of mechanical clutch, this clutch method, in fact, after the release, the axial pressure is not removed, the power supply of the electric screwdriver is not cut off, the clutch will still produce an impact additional tightening torque, so when we hear the electric screwdriver internal “da da da da” clutch release sound, this time it means that the torque reached the preset maximum. Even if you continue to press the switch, the batch head will not continue to rotate, which is actually the clutch trip inside the power tool, such a design, in fact, the main purpose is to prevent a miracle to screw or screw off to loosen the power switch in time.

If you are designing an electric screwdriver, please contact us and we will be happy to provide you with brushless DC motor solution support. INEED Motors has decades of experience providing OEM’s with application specific DC motor, micro brushless motor and gear motor solutions. Submit an inquiry and Selection Guide to get started by today.