A torque wrench prevents but do not avoid over tightening!
When the required torque is reached, the torque control system of the wrench will be “activated”, and the operator will hear a clear click sound.
In simple terms, you need torque to create tension in a bolt. You use torque to turn a nut onto a bolt and then to stretch the bolt, making it a solid spring that clamps the two materials together.
When installing the wheels on a vehicle after servicing, it is important to torque the lug nuts properly. Lug nuts that are not tightened correctly can ruin wheels, affect rotor runout and can be deadly if the wheel comes off or studs snap. Over-torqueing the lug nuts does not affect runout immediately.
When working with your torque wrench, avoid using pipes or other objects to extend the wrench handle. Not only is this practice dangerous, it can also damage the tool and throw off its accuracy. Torque tools are designed to make things tighter, but some can also work to loosen bolts.
Torque is a measure of the force that can cause an object to rotate about an axis. Just as force is what causes an object to accelerate in linear kinematics, torque is what causes an object to acquire angular acceleration. Torque is a vector quantity.
The maximum torque is approximately one and one-half times the torque obtainable at the grip-span diameter. Female torque capability is about 40 percent of that of males. The grip-span and maximum-torque diameters do not vary greatly between males and females.
At a greater distance from the axis the arc is larger, there is more distance to cover the same angle. So if the work required is the same but it is applied over a greater distance, you will need less force.
Double checking your torque is never a bad thing.
By double clicking, you are allowing the fastener to rest for a second, then you are back at it to get the proper amount of torque there. This is the only other reason besides habit I can tell you why someone would do this.
In these applications, a torque wrench is the proper tool to use instead of a plain ratchet. Fortunately, in all but the tightest or most specialized of applications, ratchet torque wrenches can be used.
Typically, an under torqued bolt will deform and be unable to provide as much clamping force as needed. An over torqued bolt will break.
