fasteners with hex (6-sided) heads. However, 12-point sockets can be used with either square- head or hex-head bolts. Sockets of the 6-point type are most popular. Various kinds of socket handles are made to fit into the square drive opening of the socket. A ratchet, Figure 2-11, is the most commonly used socket handle. Ratchets have a quick-flip reversing lever for instant reversal of socket rotation. Using excessive force can damage the ratchet mechanism. A breaker bar is the strongest socket handle. It is used when breaking loose extremely tight nuts and bolts. After the bolt or nut is loosened, the ratchet handle is used to finish removing the fastener. Extension bars, Figure 2-12, are used to add 2.2.8 Socket Wrenches A socket is an individual, cylinder-shaped box-end tool, used with a handle to perform the same turning tasks as other wrenches. One end of the socket fits over the bolt head or nut. The other end has a square opening for attaching the drive. Sockets are available in multiple sizes and are often sold in sets like the one shown in Figure 2-9. As shown in Figure 2-10, the square drive opening of a socket may be ¼″, ⅜″, ½″, or ¾″. The drive size is a measure of the socket’s capacity to withstand torque. Small drives are used for small fasteners large drives are used for large fasteners. Socket nut openings may be 4-point (square), 6-point, 8-point, or 12-point. The 4-point and 8-point sockets are used on nuts and bolts that have square heads. The 6-point sockets have more grip area than 12-point sockets both are used on Goodheart-Willcox Publisher Figure 2-9. A typical socket wrench set. Goodheart-Willcox Publisher Figure 2-10. Sockets are available in several drive sizes and point configurations. Goodheart-Willcox Publisher Figure 2-11. Ratchet handles allow tightening or loos- ening of fasteners when only limited swing space is available. A reversing lever allows easy change of direction. 20 Heating and Cooling Essentials Copyright Goodheart-Willcox Co., Inc.