The Open, Box and Combination Wrench
A wrench is a tool specially designed to tighten or loosen nuts, bolts, studs, and pipes. Wrenches are forged from steel alloy to prevent breakage. There are many different types of wrenches. Each type has its own use. By using the properwrench for the task to be done, you will not break the wrench, damage the equipment, or cause personal injury. The following section is intended to give you information on the different wrench types.
Open-end Wrench
All open-end wrenches have open jaws on one or both ends of the wrench. Most jaw openings are offset from the shank portion of the wrench by 15 degrees. The wrench length is determined by the size of the jaw opening.
Box Wrench
A box wrench surrounds the nut, bolt head, or stud on all sides. It is available with both 6-point and 12-point openings. The 12-point opening is more common, as it may be used on both square and hexagonal bolt heads. Box wrench openings are offset from the shank by 15 degrees. A box wrench should be used whenever possible, as it provides the best protection to both the user and the equipment. The major disadvantage of the box wrench is that there must be enough clearance above and around the bolt head to place the wrench over the bolt head.
Combination Wrench
The combination wrench combines the best features of the open-end and box wrench into a single wrench. The size opening on the wrench is the same on both ends, but one end has a box head and the other end has an open-end head. The length of the wrench varies with the size of the head. The most common opening is offset from the shank by 15 degrees. They are used to remove common-size nuts and bolts.
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