Click type torque wrenches work by providing an audible signal when a specific torque setting is reached, preventing over-tightening or under-tightening fasteners.
These wrenches utilize an internal mechanical system, primarily involving a spring-loaded lever and an adjustment mechanism. The user sets the desired torque value by twisting the handle, which compresses or releases the spring against the lever.
The Mechanism Explained
Here's a breakdown of the internal action:
- Setting the Torque: The user rotates the wrench's handle or a dial. This action adjusts the tension of a spring-loaded lever inside the wrench. The higher the desired torque setting, the greater the spring tension applied against the lever.
- Applying Torque: As the user tightens a bolt or nut, torque is applied to the wrench's head and transferred through its body.
- Reaching the Limit: This applied torque creates force on the internal mechanism, specifically acting against the resistance provided by the spring-loaded lever.
- The "Click": When the applied torque equals the tension set by the spring (the required torque level), the force overcomes the spring's resistance. The reference states, "When the required torque level is achieved, the lever breaks which creates a clicking noise." This means the lever rapidly moves or disengages from its resting position. This sudden movement causes the distinct audible clicking sound.
- Reset: After the click, the lever often resets automatically, and the wrench may allow further rotation (though no additional torque is applied at the set level) until it is lifted off the fastener.
Essentially, the internal spring tension acts as a calibrated limit. Once the force from tightening the fastener exceeds this pre-set limit, the mechanism signals completion with the click.
Key Components
| Component | Function |
|---|---|
| Spring-Loaded Lever | Internal mechanism providing resistance |
| Adjusting Handle | Used to set the desired spring tension/torque |
| Internal Spring | Provides the counter-force against applied torque |
| Head/Drive | Connects to sockets for fastening |
Understanding how the spring-loaded lever system works ensures accurate torque application for critical components in automotive, construction, or assembly tasks.
