While an adjustable wrench, often called a Crescent wrench, is convenient, it should be a tool of last resort in an auto shop. It features a thumbwheel screw that adjusts the opening width, allowing one wrench to fit metric and standard fasteners. However, because the jaw has slight play, it easily slips under high torque, rounding off bolt heads. If you must use one, ensure the jaw is tightened completely snug against the flats of the bolt, and pull the wrench so that the force is directed toward the fixed, stronger jaw.
Mechanic Glossary
Adjustable Wrench
A wrench with a moveable jaw that can be adjusted to fit various sizes of nuts and bolts.
Frequently Asked Questions
The adjustable jaw flexes and has built-in play, which concentrates all the force on the corners of the bolt instead of the flat sides, quickly rounding the fastener.
Always pull the wrench toward the side with the adjustable jaw. This keeps the stress on the stronger, fixed part of the wrench body.
Yes, they are great for low-torque brass fittings, sensors, or alignment bolts where exact-sized wrenches are not available.