A strap wrench is any of various types of
wrench that grip an object via a
strap
A strap, sometimes also called strop, is an elongated wikt:flap, 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 s ...
or
chain
A chain is a 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 but linear, rigid, and load-bearing in tension. A c ...
being pulled in
tension around it until it firmly grips. High
static friction 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
polymers, and are smooth, highly flexible, non-marring, high-friction straps. (Before the era of commercial polymers, the straps were of
leather or
rubber.) 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 type (like a
bicycle chain).
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
sprockets on a
bicycle
A bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A is called a cyclist, or bicyclist.
Bic ...
. 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
The Rotafix is a method of tightening or loosening a sprocket on a track bike or fixed gear bicycle.
Method
The Rotafix enables the securing of a sprocket ("cog") to a track hub without the use of a chain whip.
The chain is removed from the ...
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-tig ...
long enough to slide it into a
cylinder. 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