Referred to as adjustable spanners, adjustable wrenches and shifters, these tools differ from ordinary spanners and wrenches by nature of the 'jaws' being able to adjust to fit an individual nut, bolt or other fitting. The mechanism for adjusting the jaws varies between designs and nature of the job they are intended for.
Though there are several claimed inventors, the earliest recorded adjustable spanner is attributed to English engineer, Richard Clyburn, in 1842*
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This 16" Connolly shifter is the only complete one found. They seem to be very uncommon. Any info contact the Curator. (Image J Hawking)