Box-end wrench – A box (closed) end wrench has an enclosed opening with fixed points that grips the ‘corners’ of the faces of a bolt or nut. They are used where there is room to place the wrench opening around the fastener. Since the sides of the box are thin, these wrenches are used to turn fasteners that are difficult to reach with an open-end wrench. Box end wrenches are available with a six-point or twelve-point opening. They are often double-ended and the ends are different sizes. The handles are usually offset to allow easier access to the nut or bolt.
- Ratcheting box wrench: This is a special type of box wrench, whose end enclosures ratchet. This allows a bolt or nut to be loosened or tightened without having to remove and reposition the wrench. Some ratcheting box wrenches have a one way ratchet and must be flipped over to change direction. Others have a dual direction mechanism that can change direction by moving a small lever. Look here for more information on a Ratcheting Wrench.
Open-end wrench – The open end wrench is a one-piece unit with a U-shaped opening that grips two opposite faces of a bolt or nut. This wrench usually has different-sized openings at each end. The ends are often oriented at an angle of around 15 degrees to the handle. This allows easier access to the fastener in tight spaces by flipping the wrench over.
Combination wrench – A combination wrench is a double-ended tool that has ends that are different. One end may be an open end and the other end may be a box end. One end may be straight and the other may be offset. Sometimes one end may be a ratchet type. Both ends are normally the same size.
Adjustable wrench – An adjustable wrench is a type of wrench with a movable jaw that adapts to different sized nuts or bolts.
- Adjustable end (Crescent) wrench: This is the most common type of adjustable wrench. The adjustable end wrench is similar to an open end wrench but the spacing is adjustable. It has smooth jaws that mate with two opposite faces of a fastener.
- Monkey wrench (gas grips): The monkey wrench is a type of adjustable end wrench with a straight handle and smooth jaws that have gripping faces perpendicular to the handle. It is still available but the adjustable end wrench has taken its place in many applications.
- Pipe (Stillson) wrench: The pipe wrench looks similar to a monkey wrench. It has loose jaws that tighten when pressure is applied. The jaws have harden serrated teeth that securely grip soft iron pipe and pipe fittings. The teeth can often be replaced.
Socket wrench – A socket wrench consists of a socket and a drive handle. The socket fits over the fastener which allows for a more secure configuration than with other wrenches. It may have a six-point, eight-point or twelve-point recess. Sockets come in standard and extended depth. The sockets also have different drive sizes such as 1/4, 3/8, 1/2 or 3/4 inch.
Some various drive handles used with sockets are:
- Ratchet handle: This handle allows the socket to be turned without removing it from the nut or bolt by moving the handle backward and forward. A small lever, determines the socket wrench direction.
- Break-over or breaker: This tool is a long non-ratcheting bar that allows the user to apply considerable torque to the socket, to break loose a difficult-to-loosen fastener.
- Speed handle, crank handle or speed brace
- Screwdriver handle
Torque wrench – The torque wrench is actually a special socket wrench drive tool that has a measuring device built in to allow a nut or bolt to be tightened to a certain torque specification. There are different types of torque wrenches. The simplest type is known as the beam type which has a long pointer attached to the head of the wrench and an indicator scale near the handle. There are also electronic types that have electrical sensors and digital readouts. Some torque wrenches have adjustable settings so the drive ‘slips’ when the desired torque is reached.
Impact Wrench – Impact wrenches are powered tools that are able to apply a high level of torque with minimal physical effort by the user. Most powered impact wrenches use compressed air, but less powerful electric versions are also available. The most common designs are inline and pistol grip.`