Final answer:
An adjustable wrench, also known as an adjustable spanner, has a movable jaw that adjusts to fit different sizes of nuts or bolts. It is turned counterclockwise to loosen and clockwise to tighten a nut as per Figure 2.31.
Step-by-step explanation:
A tool that has a movable jaw to adjust to different sizes of nuts or bolts is commonly known as an adjustable wrench or adjustable spanner. This versatility makes it an essential tool in many toolkits for various applications. To operate, the user can turn a screw located on the bottom of the head of the wrench, which moves the jaw in or out, thereby adjusting the size of the opening to fit the nut or bolt. This tool simplifies tasks by accommodating multiple sizes, eliminating the need for multiple fixed-size wrenches.
When using an adjustable wrench, you would place the jaw of the wrench around the nut or bolt, ensuring a snug fit by adjusting the movable jaw accordingly. Then, according to the figure provided (Figure 2.31), you would turn the wrench counterclockwise to loosen the nut or clockwise to tighten it. A good grip and accurate adjustment are crucial for the wrench to be effective and prevent slipping, which can round off the edges of the fastener.