A strap wrench is any of various types of

wrench A wrench or spanner is a tool used to provide grip and mechanical advantage in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning. In the UK, Ireland, Australia, and New Zeala ...

that grip an object via a

strap A strap, sometimes also called strop, is an elongated flap or ribbon, usually of leather or other flexible materials. Thin straps are used as part of clothing or baggage, or bedding such as a sleeping bag. See for example spaghetti strap, ...

chain A chain is a wikt:series#Noun, serial assembly of connected pieces, called links, typically made of metal, with an overall character similar to that of a rope in that it is flexible and curved in compression (physics), compression but line (g ...

being pulled in tension around it until it firmly grips. High

static friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of tw ...

keeps it from slipping. Many strap wrenches have built-in handles. Others are made to receive the square drive of a ratchet wrench. The strap or chain can have various forms. Some straps are made of

polymer A polymer (; Greek ''poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and ...

s, and are smooth, highly flexible, non-marring, high-friction straps. (Before the era of commercial polymers, the straps were of

leather Leather is a strong, flexible and durable material obtained from the tanning, or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle, sheep, goats, equine animals, buffalo, pigs and ho ...

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, a ...

.) Other straps are bands of spring steel, moderately flexible, slightly firmer and more likely to mar than the polymer variants. The chains tend to be of the

roller chain Roller chain or bush roller chain is the type of chain drive most commonly used for transmission of mechanical power on many kinds of domestic, industrial and agricultural machinery, including conveyors, wire- and tube-drawing machines, pri ...

type (like a

bicycle chain A bicycle chain is a roller chain that transfers power from the pedals to the drive-wheel of a bicycle, thus propelling it. Most bicycle chains are made from plain carbon or alloy steel, but some are nickel-plated to prevent rust, or si ...

Types

Oil-filter wrenches

Many oil-filter wrenches are actually strap wrenches. Others are of the socket type or the pliers type.

Chain whips (e.g., for bicycle work)

A chain whip is a tool used to tighten and loosen threaded

sprocket A sprocket, sprocket-wheel or chainwheel is a profiled wheel with teeth that mesh with a chain, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial projections engage a chain pass ...

s on a bicycle. It is called a chain whip because it has a short section of chain used to grip the sprocket. An alternative method to tighten sprockets is the rotafix method, which uses no tools.

Piston-ring compressors

Piston-ring compressors are strap wrenches that evenly squeeze (compress) the piston rings around a

piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas- ...

long enough to slide it into a

cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infi ...

. They look a lot like an oil-filter wrench of the strap type (except they are a flat piece of metal that wraps around the piston). If no wrench is available, an old piston ring snapped into two halves can be used to compress each of the new rings as the piston is inserted.

Gallery

File:Strap wrench.JPG, A strap wrench variant. File:Oil-filter-wrench.jpg, A strap wrench variant (one form of oil filter wrench). File:Oil filter wrench 001B.jpg, A strap wrench variant (one form of oil filter wrench). File:Oil filter wrench 002B.jpg, A strap wrench variant (one form of oil filter wrench). File:Chain whip tool.jpg, A chain whip tool, wrapped around a sprocket. {{Bicycle tools Bicycle tools Chains Wrenches