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How a manual impact screwdriver works

  How a manual impact screwdriver works

A manual impact screwdriver, also known as an impact driver or impact screwdriver, is a special screwdriver tool primarily used to provide extra impact when tightening or loosening screws to overcome the friction between the screw and the workpiece or rust. Its working principle is mainly based on the combination of manual operation and internal mechanical structure to produce instantaneous impact.

Here’s how a manual impact screwdriver works:

basic structure:

Screwdriver head: similar to an ordinary screwdriver, with different specifications and shapes of bits used to match the screw notch.

Main part: Contains a handle and internal mechanical structure.

Impact mechanism: Located inside the screwdriver, it is the key part that generates impact force.

Operation method:

The user holds the handle and aligns the screwdriver head with the screw.

The internal impact mechanism is activated by quickly turning the handle or pressing the specific impact button (if the design has one).

The working principle of the impact mechanism:

When the user quickly rotates the handle or presses the impact button, some part of the impact mechanism (such as a spring, slider, or cam) is compressed or displaced.

Once a certain threshold is reached, the part releases suddenly, creating an instantaneous impact.

This impact force is transmitted to the screw through the screwdriver head, helping to overcome friction or corrosion between the screw and the workpiece.


Manual impact screwdrivers require no external power or air source and rely entirely on manual operation.

Because of its impact, it can more effectively tighten or loosen hard-to-turn screws.

However, since the magnitude and frequency of impact force are affected by human factors, caution should be used to avoid damaging screws or workpieces.

In general, the working principle of a manual impact screwdriver is to activate the internal impact mechanism through manual operation, producing an instantaneous impact force to help tighten or loosen the screws. This tool is particularly useful in situations where significant friction or rust needs to be overcome.

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