Wrench

A wrench or spanner is a tool used to turn bolts, nuts or other hard-to-turn items. There are many types of wrench, including the:

• open-ended spanner: a one-piece spanner that grips two opposite faces of the nut
• adjustable spanner/wrench: an open-ended spanner/wrench with adjustable (usually smooth) jaws
• monkey wrench: adjustable wrench with serrated jaws (depicted above right)
• ring spanner (box wrench): a one-piece spanner that encloses the nut on all sides
• combination spanner: a double-ended tool with an open-ended spanner at one end and a ring spanner at the other
• spoke wrench
  
• Allen wrench
• hand wrench
• pipe wrench
• strap or chain wrench: a self-tightening strap or chain attached to a handle, used to grip and turn smooth cylindrical objects
• oil-filter wrench: a type of chain wrench for removing cylindrical oil filters
• socket spanner/wrench: a hollow cylinder that fits over one end of a nut - may include a handle but usually used with various drive tools
• box spanner: a tube with a socket formed at one end, that can reach a nut at the bottom of a hole or in a restricted space
• flare nut wrench: a ring spanner (box wrench) with a cutout so that it may be used on a tubing nut (flare nut) and then removed by passing out over the tubing.