Izod Impact Testing Machine

Many years back West Yorkshire Steel purchased an Avery Izod Impact Testing Machine from Coghlan Bright Steel in Leeds.  This machine dating back to the early 1900s has a wonderful history which was provided to us by Brian Wilby an old employee of Coghlan’s.

The machine was originally purchased with a 50 ton capacity Denison Universal Tester, several weeks before Coghlans became the first Bright Steel Producer to be DEF STAN 05-24 registered.

Historically, the machine was used to test all barrel and anchor wedge materials used to construct Bosporus I, Bosporus II and the Humber suspension bridges. The barrels were made from special high residual carbon steel, treated to give superior physical properties to traditional alloy steels. The intention was to maximise tool life and surface finish direct from turning.

The material used for cable connectors was also tested on our machine. One third of the total material processed was used to repeatedly demonstrate the uniform properties to the various inspection authorities. The connectors were made from high tensile EN24 ‘W’ condition alloy steel with extra high impact values. The items were crimped on the ends of individual wire strands joining them to make them long them long enough to span the stretch of water being bridged. Many such wire were bound together to form the huge cross-section of the main cross-river cables that carry the carriage ways. Most of the steel used was produced by the Park Gate Iron & Steel Company, Sheffield – have a look at some great footage of workers arriving at the steel mill in 1901. Unfortunately the Park Gate Works was a casualty of the demise of the UK steel manufacturing industry in the 1970s and 80s.

The machine was used in numerous other testings. Testing steels for extra high impact values, many products were used for railway carriage connector bolts and land tractor units. The machine was used to test heat treatment experiments using timed interruptions during water quenching of high carbon and alloy steels. The process, later used as a standard method, produced a high tensile strength and high impact values  from low cost steels.

Unfortunately our machine has deteriorated over the years but to see one visit the Kelham Island Museum in Sheffield.