A torque wrench is any device that applies a pre-determined amount of torque to a fastener.
• It may be mechanical or electronic in design.
• A torque wrench has some type of indicating device which lets the operator know when the correct torque has
been achieved: "click" or "impulse-break"; feel; sound; lights; gauge; or some combination of these.

Quick Fact: The Micrometer Click Type Wrench (Shown) is the most affordable and common torque
wrench used today.


• Bolts (or threaded fasteners), are designed to create clamping force, also called “clamp load”.
• When torque is applied to a threaded fastener, it draws together the joint, (two pieces of material).
• As additional torque is applied to the fastener, the joint is pulled together creating a clamp load as
the fastener begins the stretching process. It’s this fastener stretch that creates and maintains
clamping force, like a stretched bungee cord
• The actual amount of clamp load is determined by several factors:
- The amount of torque applied to the fastener.
- The material and grade of the fastener.
The external friction on the joint — friction under the fastener head, and friction between the threads of
the fastener and material it’s connected to.