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Wrench - a tool used to provide a mechanical advantage in applying torque to turn bolts, nuts or other hard-to-turn items.

  • open-end wrench - a one-piece wrench with a U-shaped opening that grips two opposite faces of the bolt or nut. This wrench is often double-ended, with a different-sized opening at each end.
  • box-end wrench - a one-piece wrench with an enclosed opening that grips the faces of the bolt or nut. The recess is generally a six-point or twelve-point opening for use with nuts or bolt heads with a hexagonal shape.

Adjustable wrench - an open-ended wrench with adjustable (usually smooth) jaws, also sometimes called by the original patent holder's brand name as a Crescent Wrench
  • Pipe wrench - an adjustable-end wrench with self-tightening properties and hard serrated jaws that securely grip soft iron pipe and pipe fittings.

Torque wrench - a socket wrench drive tool that measures the amount of rotational force applied to the socket—this may be indicated visually with a rod or dial or may simply slip when a set torque is exceeded. The torque wrench would also be categorized as a measuring tool.

gripping / clamping


What's the problem?
  • Ask - Wrenches are handy tools for lots of jobs. Bolts come in a wide variety of sizes. Open-end and box wrenches must fit the exact size of the bolt. Having a single tool to use in a variety of situations would be useful.
  • Imagine - An open-ended wrench in one size, can't be used on any other size of bolt. They have to fit exactly to grasp the bolt to get the leverage from applying force to the handle. How could an open-end wrench be modified to be adjustable? What part would move?
  • Design, Build - Being able to spread or contract the distance between the sides of the wrench would solve the problem. What mechanism could be used to adjust the moveable side of the new wrench design?
  • Improve - How has the adjustable wrench changed over time? How has it been improved?

That's engineering
  • screw - 1. A spiral path along a cylinder. 2. A fastening device. A screw is like an inclined plane wrapped up. It can take a rotating force and change it into a much larger straight-line force. 3. Used to make the adjustable wrench adjustable. Rotating the screw, connected to the movable side of the wrench makes the moveable side move in and out.

Engineering ideas
  • mechanical advantage, torque, nuts, bolts, rotational force, measurement

Do It
Challenges for you to work on...
  • design a mechanism for an adjustable wrench

News, updates

Learn more...

2018.2.15 * https://wikieducator.org/User:Vtaylor/e4k/Adjustable_wench * https://engineering4kids.org/2018/02/15/adjustable-wrench/
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