Convertisseur de couple

Torque is a measure of rotational force applied to an object around an axis. It equals the force multiplied by the distance from the axis of rotation (the lever arm). The SI unit is the Newton-meter (N·m), which represents one Newton of force applied at one meter from the pivot point. In imperial systems, pound-force feet (lbf·ft) is the most common unit. Torque is critical in mechanical engineering, automotive work, and any application involving fasteners or rotating machinery.

Newton-meters (N·m) use the SI unit of force (Newtons), while kilogram-force meters (kgf·m) use the gravitational force on one kilogram as the force unit. One kilogram-force equals 9.80665 Newtons (standard gravity), so 1 kgf·m equals 9.80665 N·m. Newton-meters are the standard in modern engineering and scientific work, while kilogram-force meters are still found in older specifications and some regional standards.

To convert pound-force feet (lbf·ft) to Newton-meters (N·m), multiply by 1.3558179483. For example, 100 lbf·ft equals approximately 135.58 N·m. This conversion is commonly needed when working with American automotive specifications in metric workshops, or vice versa. The conversion factor comes from the exact definitions: one pound-force is 4.4482216 Newtons, and one foot is 0.3048 meters.

Applying the correct torque to fasteners ensures they are tight enough to hold securely but not so tight that they strip threads, crack components, or cause material fatigue. Under-torquing can lead to loose connections that vibrate apart, while over-torquing can stretch bolts beyond their elastic limit, causing failure. Critical applications like automotive wheel lug nuts, engine head bolts, and structural connections all have precise torque specifications that must be followed.