Water Pressure Machinery
In 1838 William George Armstrong reported to the Mechanic's Magazine his ideas of a hydraulic water powered crane. Working with the Newcastle Water Company gave him further opportunities of testing his machines. [[http://www.machine-history.com/Armstrong%20Rotary%20Water%20Wheel%20Engine|Some of the water motors were rotary type]] but the one he finally stayed with for the successful cranes used a piston or ram with leather seals. He developed his ideas for a hydraulically operated crane based on the hydraulic jigger, comprised of a ram in a closed cylinder arranged with multiple pulley sheaves at each end so as to multiply movement of the free end of a chain or rope wound around the sheaves when a pressurized fluid, normally water, was admitted into the cylinder. The hydraulic jigger operated in the reverse manner to the conventional block and tackle. The pulley system amplified the distance the lifting rope moved for a given movement of the piston, this also meant that the load moved up or down a lot faster than the piston. By a suitable valve the water was admitted into the lifting cylinder when the weight on the chain was to be raised, and suffered to escape when the weight was to be lowered.
'To avoid dangerous jerks by the sudden dosing of the outlet when the weight was being rapidly lowered, a small clack valve was applied, opening upwards against the pressure in the supply pipe, so as to permit the pent-up water in the cylinder to be pressed back in the supply pipe, whenever the compression in the cylinder exceeded the pressure of the water in the pipe. The slowing cylinder was also fitted with an appropriate valve for admitting .the water to either side of the piston; while it allowed an escape from the opposite side. Relief valves, similar to the one described were likewise applied at each end of the slowing cylinder to save the machinery from being, broken, or strained, by the momentum of the jib when the regulating valve was suddenly closed.' (The Institution of Civil Engineers (Great Britain))
His first working model was used at Newcastle with pressure from the street water pipes. It was so successful it attracted interest from railroad and dock shipping companies. Armstrong soon started building these cranes with his new Elswick Engine Works.
In later adding accumulators, Armstrong said 'when water is lifted by a pumping engine it becomes the recipient of the power exerted in raising it, and if the same water be used as a motive power in its descent to its original level, it renders back the power conferred upon it by the engine, and thus becomes the medium through which the power of the pumping engine may be transmitted to a distance, and distributed in large or small quantities as occasion may require.' This consisted of a tall tower containing a water tank with a weighted piston mounted at the top or just tanks and water volume high enough to supply the needed energy. A steam engine pumped the water into the tank or tanks and the weight on the piston or height of water provided the pressure.
This first image is probably of the 5 ton crane type with hydraulic jiggers used for both the hoisting and slewing motions. The source of the pressurized fluid for these early hydraulic cranes was the 150,000 gallons of water stored in the upper floor of The Granary of the [[http://www.machine-history.com/London%20Terminus%20of%20The%20Great%20Northern%20Railway|London Terminus of Great Northern Railway]]. Water pressures could be obtained in this way to act on the ram within the individual hydraulic jiggers, with control by way of lever operated three-way valves.