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| Keywords: Stackfreed.png Drawing of early 16th century pocketwatch movement with stackfreed mainspring compensating device The stackfreed is the eccentric cam near the top engaged by the long springloaded roller arm It's purpose was to compensate for the decline of the mainspring's force as it unwound Early in the watch's running period when the mainspring is fully wound and providing maximum torque the stackfreed roller rests against one side of the depression in the cam exerting a force which opposes the mainspring Later in the running period when the mainspring is almost run down and is providing less torque the stackfreed roller rests on the other side of the cam notch and it's force aids the the mainspring The dumbbell-shaped device under it is the watch's primitive balance wheel the foliot The adjoining source text seems to refer to this as a watch made in the 16th century from the Soltykoff Collection Alterations removed caption sharpened converted to PNG Downloaded from http //books google com/books id 7DcDAAAAQAAJ pg PA24 Nelthropp Harry L 1873 A Treatise on Watch-work Past and Present E F N Spon London p 60 fig 3 on Google Books 1873 Harry Leonard Nelthropp Public domain - author has been dead more than 70 years PD-old Old horology prints Stackfreed Soltykoff Collection | ||||
