Top quality wrenches are forged from fine-grade tool steel, machined to close tolerances, hardened and tempered for long service life.
Types include open-end, box- end, combination box/open end, adjustable, socket and locking grip styles.
Because most imported products are made to metric specifications a set of metric wrenches has become a must in many home workshops.
A wrench’s main function is to hold and turn nuts, bolts, caps, screws, plugs and various threaded parts. Applying excessive torque will strip or damage those threads, so quality wrenches are designed to keep leverage and intended load in safe balance. Users should not put “cheaters” on wrenches to increase leverage.
The proper size wrench should be used. Too large a reach will spread the jaws of an open-end wrench or damage the points of a box or socket wrench. When possible, a wrench should be pulled, not pushed.
Open-end wrenches provide gripping power on two sides of the head with another side open so the wrench can be placed on a nut, which might not be accessible to a closed or box wrench. Open-end wrenches have different size openings on each end and should fit the nut exactly to prevent mutilating the nut edges.
Box wrenches have enclosed heads and provide more leverage by completely enclosing the nut. Some are offset to provide knuckle room and clearance over obstructions. They are available with either 6 or 12-point ends (gripping angles).
Combination wrenches are a box and an open end on opposite sides of the same wrench. Both ends are usually the same size. These are the most popular of all wrench styles.
Adjustable wrenches come in two styles, locking and non-locking. Non-locking style features an adjustable end opening with little provision made for slippage.
The locking style also has an adjustable head, but uses a locking mechanism to secure jaws in desired position, eliminating the need for constant readjustment. When properly adjusted to nut or bolt, it will not slip.
Pipe wrenches screw pipes into elbows or other threaded devices. Jaws actually bite into the surface to hold it for turning. They should never be used on plated pipe installations because they will badly scar the finish.
Aluminum pipe wrenches are popular among professionals because of their lighter weight, but they are more expensive.
Socket wrenches combine an offset handle with a male drive piece which has a spring-loaded bearing to lock on various size sockets. They can be used at almost any angle since handles may be attached to the head by a jointed hinge device.
Many socket wrenches have a ratchet handle, making reversing possible in confined spaces.
Socket wrenches come in two basic sizes or drives, 3/8″ and 1/2″. Sockets themselves are available with 6, 8 and 12 point gripping ends. They also are available in metric sizes.
A socket wrench makes the job of tightening or loosening nuts faster and easier than conventional wrenches. It also provides a snug grip on all sizes of nuts, even worn ones.
Ratchet wrenches are available in 1/4″ 3/8″ and ½” drive sizes and are used with socket wrenches. They are available with a round or teardrop-shaped head, and contain a reversing mechanism to facilitate tightening or loosening a fastener. Ratchet wrenches are available in a variety of handle shapes and lengths.
Accessories that can provide a drive means to socket wrenches include flex handles, speeder handles and T handles. Extensions of various lengths and universal joints can be used with ratchet wrenches and socket wrenches to work on fasteners in hard-to-reach locations.
Chain wrenches are designed for easy use in extra-close quarters-on round, square or irregular shapes.
Locking wrenches are one of the most versatile hand tools found in home or shop. Through a locking action, jaws can be locked in a holding position with pressure up to one ton. They can also be used as hand vises, holding clamps, pipe wrenches and hand vise pliers. They are available with both curved and straight jaws.
Torque wrenches are designed to permit an operator to determine applied torque on bolts, nuts and other fasteners. They measure torque in ounce-inches, pound- inches and pound-feet, as well as metric measure. However, many manufacturers express torque in foot-pounds (rather than pound- feet) since this nomenclature is more familiar to the average tool user.
Metric measure torque wrenches are available in Newton meters (N.m), meter kilograms (mkg) and centimeter kilograms (cmkg) with N.m becoming the more modern, universally accepted calibration. Many torque wrenches are available with dual scales for conventional and metric measurements.
Two basic hand torque wrenches are audible signal and visual display. The audible signal type signals applied torque by momentarily releasing the wrench for a few degrees of free travel. The release is usually accompanied by a click sound, which gives the wrench its popular names: click torque wrenches or clickers. Torque value is set to a micrometer scale on the handle or preset by an adjusting screw in the handle cavity.
The visual display type indicates applied torque on a dial or electronic display. Some models have memory pointers, which remain at the maximum reading attained until manually reset.
For low-torque application, torque screwdrivers are usually used. They are available in either the release or indicating type. The most widely used torque wrenches have square drives to use standard detachable sockets. Both ratcheting and non-ratcheting types are available. Torque wrenches are used in various operations where proper torquing of nuts, bolts and other fasteners is critical. For example, assembly and inspection of gear trains and bearings, setting of clutches and brakes, overhaul and experimental work.
- Always work with clean threads free of corrosion.
- Follow the product manufacturer’s instructions for specific torque loadings, particularly whether recommendations are for dry, oiled or plated threads.
- Avoid over-tightening a nut or bolt with a conventional wrench before applying a torque wrench.
- When not in use, set at lowest torque.
- Never use it as a hammer, pry or conventional wrench.
- Avoid dropping. If dropped, check accuracy on a torque tester.
- When using adjustable wrenches, do not over-torque by applying torque past the release point. Learn the feel of the release rather than relying on the sound.
- Read torque values on indicating torque wrenches by looking at the dial at 90 degrees to its surface.
- When in frequent or continuous use, periodically check calibration accuracy.
Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the North American Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.