Nelson Dock, hydraulic slipway winch.
Introduction
The photograph on this page of Nelson Dock, hydraulic slipway winch. by Chris Allen as part of the Geograph project.
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Image: © Chris Allen Taken: 21 Aug 2011
Preserved as part of the Hilton Docklands Hotel. Built by the Hydraulic Engineering Company, Chester and claimed to be of 1900 vintage. It 'feels' older. The meat of the machine is a long stroke single acting hydraulic cylinder that physically hauls the vessel up the slipway the length of its stroke. At the top of the stroke a pawl and rack arrangement stops the vessel from sliding back, the ram is retracted by a weight, the chain/links to the vessel are shortened and the cycle repeats. There is a three throw hydraulic pressure pump hidden below the main piston rod and this was driven by an external power supply (almost certainly a steam engine) by the gears on the left. The gears could also drive a winch barrel, presumably for lesser loads and a pair of dog clutches selected pump or winch barrel. I have never seen anything quite like it before and it is a marvellous survivor.