A swivel socket is a specially designed metal tool that is used for tightening or loosening bolts. The head of the socket swivels in different directions to allow a user to access bolts in tight spaces or at awkward angles. The socket is attached to a driver that the user turns and applies force to for leverage to loosen or tighten the bolt. Swivel socket designs can vary according to the purpose of the tool, and the size of the socket opening can vary as well to accommodate different bolt sizes.
One popular swivel socket design features a ball joint; the part of the socket that fits onto the driver features a ball end that is fitted into the socket frame. This allows the frame to move in a circular motion in relation to the socket ball, which is attached to the driver to apply force. The joint functions similarly to a human's hip joint, which allows circular movement to the leg. A swivel socket set will include several socket sizes with this ball joint design to allow for more flexibility when dealing with bolts of different sizes.
Another type of swivel socket may only swivel in one or two directions. Some box wrenches feature a swivel socket at the other end of the tool, and the socket will only swivel in a forward and backward orientation. This is a useful addition to the box wrench, but the user will be limited in the application of the socket, since it may not be able to swivel in the direction needed to access a bolt in a difficult orientation. This situation is commonly encountered when working on automobile engines, on which bolts may be oriented in a strange direction or it may be located in a very tight spot.
To increase the usability of a swivel socket, the socket may be attached to an extender that is affixed to the end of the socket driver. This extends the length of the socket, but it does not increase the socket's overall mobility. Most sockets only swivel in a forward and backward direction to ensure the user can apply torque to the driver without the tool slipping or failing to affix cleanly to the bolt. One of the drawbacks of using swivel sockets is the decreased strength of the unit: adding a joint to the socket invariably decreases its strength and resistance to torque damage, though most sockets are durable enough for regular use.
