Wrenches

A wrench or spanner is used to provide grip and mechanical advantage in applying torque to turn objects. They are available in a variety of forms and the size marked on them relates to the size of the nut/bolt or the distance across the flats.

The various types of wrenches/spanners are discussed below.

Open-End Wrench: It is made of high carbon steel like most of the hand tools and comes in different sizes. The length is indicative to the torque to be applied to the nut/bolt. The greater the size, the longer the wrench.

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Box-End Wrench: It can completely surround the nut/bolt head and can be used in places having as little as 15⁰ swing. Although these wrenches are ideal to break loose or pull tight nuts, time is lost turning the nut off the bolt once the nut is broken loose. This can be avoided when there is sufficient clearance to rotate the wrench in a complete circle.

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Combination Wrench: It has a box-end on one end and an open-end of the same size on the other end. After the tight nut is moveable, it can be completely unscrewed more quickly with an open-end wrench than with the box-end type.

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Ring Wrench: It gives full closure to the bolt head. Each corner has an angle of aperture and is usually bi-hexagonal to facilitate its use when angular movement is restricted. These are commonly available as double-ended types to fit nuts of consecutive sizes.

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Ratcheting Wrench: It swings back and forth in order to remove a nut from a bolt. The ratchet tightens or loosens the nut/bolt by pushing or pulling in one direction. It allows the ratchet handle to be re-positioned for another turn while still attached to the nut/bolt. Thus it does the job without disconnecting the tool from the fastener.

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Box Wrench: It is a fully-enclosed type cylindrical wrench with a hexagonal end that are used where the access area is restricted to the centre line of the screw axis. A steel part called tommy bar is used as a lever that is placed through the shaft of the spanner to provide leverage.

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Allen Wrench: It is an L-shaped or hex-shaped, solid type wrench that is usually made of unbreakable chrome-vanadium steel. They are non-adjustable and are designed to fit a nut or bolt head internally. Thus the contact surfaces of the nut/bolt is protected from any external damages. These wrenches can be used with a headless screw and also known as hex keys or Allen keys.

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Socket Wrench: It comprises of two parts namely a socket and a handle that are held together by a light spring-loaded poppet. The socket aperture is bi-hexagonal at one end and square at the other end in order to accommodate various attachments that comes with the tool. The handles are either fixed or detachable. The fixed handles have either 1, 4 or 6 sided recess to fit a nut/bolt head. The detachable handle types usually come in sets and fit several types of handles such as the T-shaped, ratchet, screwdriver grip and speed handles. The extensions that comes with the wrench make it possible to use these tools in various locations and positions. These wrenches are used for tightening and loosening nuts of different sizes.

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C-Spanner: It is used on ring nuts with recesses cut around the circumference to accommodate the lug of the spanner. This wrench has a curved arm with a hook on the end that fits into one of the notches on the nut and so also known as hook spanner. It is also available in adjustable types that fits nuts of various diameters.

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Peg Wrench: It has two round pegs protruding from the flat surface to engage in corresponding holes in special nut plates. These are also called as face spanners.

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Adjustable Wrench: It has a jaw of adjustable width thus allowing it to be used with different sizes of nuts, bolts and fastener heads. When using any adjustable wrench, always exert the pull on the side of the handle attached to the fixed jaw of the wrench.

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Crowfoot Wrench: It is normally used when accessing nuts that must be removed from studs cannot be accessed using other related tools.

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Flare Nut Wrench: It looks similar to a box-end wrench that has been cut open on one end, which allows the wrench to be used on the B-nut of a hydraulic line.

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