Wrench

A wrench (called a spanner in British English) is a hand tool used to provide grip and mechanical advantage when turning nuts, bolts, and other fasteners. Wrenches are the most fundamental tool in any mechanic’s or builder’s kit.

Common types

• Open-end wrench: Has a U-shaped jaw that grips two opposite faces of a hex fastener. The jaws are angled at 15° to the handle, allowing the wrench to be flipped for a greater range of motion in tight spaces.
• Box-end wrench: Has a closed ring (6-point or 12-point) that encloses the fastener completely, gripping all faces simultaneously. Allows higher torque without slipping.
• Combination wrench: One open-end jaw and one box-end ring on the same handle, both sized for the same bolt. The most versatile single wrench.
• Adjustable wrench (Crescent wrench): Has a sliding jaw that adjusts to fit a range of fastener sizes. A single adjustable wrench can take the place of a set of fixed wrenches for casual use.
• Socket wrench: Uses interchangeable sockets on a ratcheting handle — the most efficient system for working with many fastener sizes.
• Torque wrench: A wrench with an internal mechanism that signals (clicks, beeps, or shows a reading) when a preset torque is reached. Essential for critical fasteners where over-tightening is dangerous.

Why the 15-degree angle matters

Standard open-end and combination wrenches have their jaws angled at 15° to the handle. This angle lets you flip the wrench to engage the next tooth of a hex fastener, effectively doubling the usable swing arc in confined spaces — critical in engine bays and behind panels.