2.2.1 Open-End Wrenches An open-end wrench has an open jaw on each end, Figure 2-1. Each end is a different size, and the jaw opening is set at an angle. The angle permits using the wrench when there is only a small amount of room (swing space) to turn the nut or bolt. The wrench is turned over to obtain a new grip on the nut. Because they tend to slip, open-end wrenches work best on loose nuts and bolts. A slipping open-end wrench could round nut edges and cause hand injuries. 2.2.2 Box-End Wrenches A box-end wrench is closed on both ends to surround the nut or bolt head. See Figure 2-2. Each end has an opening of a different size. Opening sizes are stamped on the wrench. Box wrenches are available in 6-point or 12-point types. Points are the “teeth” that grip the edges of the nut or the bolt head. The 6-point wrench is the stronger of the two since it has more grip area. A box-end wrench will not slip easily, so it should be used on bolt heads or nuts that are tight or partially rounded. 2.2.3 Combination Wrenches Combination wrenches combine the best features of open-end and box-end wrenches. They have one open end and one box end, Figure 2-3. Both ends are usually the same size. The combi- nation wrench is designed for several tasks. The open end is useful where little swing space is available. The box end provides the grip area needed for final tightening (or loosening of tight bolts). 2.2.4 Refrigeration Service Wrenches Refrigeration service wrenches are designed to easily turn refrigeration service valve stems. The wrench in Figure 2-4 is a ratchet-type with square openings to fit most valve stems. A quick- flip reversing lever permits instant reversal for turning service valve stems in either direction. This wrench is a must in every technician’s tool kit. 2.2.5 Flare-Nut Wrenches The flare-nut wrench, shown in Figure 2-5, is a special type of box wrench with an opening in Goodheart-Willcox Publisher Figure 2-1. The openings are different sizes at each end of an open-end wrench. Goodheart-Willcox Publisher Figure 2-2. Box-end wrenches surround the nut or bolt head, making them much less likely to slip than open- end wrenches. Open end Box end Goodheart-Willcox Publisher Figure 2-3. The open end and box end of a combination wrench are usually the same size. Ritchie Engineering – YELLOW JACKET Products Division Figure 2-4. The ratchet feature of the refrigeration service wrench makes it easy to turn a service valve stem, even in tight quarters. This wrench is a necessity for every technician. 18 Heating and Cooling Essentials Copyright Goodheart-Willcox Co., Inc.