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Sydney Harbour Bridge

Board of Studies NSW

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Hydraulics problems

Problem 1

What diameter would the load cylinder in each jack need to be to allow the operation described above to be successfully carried out up to the maximum capacity of the jacks?

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Problem 2

If the operating piston in the hydraulic system is 25 mm in diameter, what force would be required on this piston to cause the jacks to extend and supply the load required to move the chords?

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Problem 3

What is the mechanical advantage of the system if two 25 mm operating pistons were used? In the hydraulic system a force of 30·3 kN in the operating piston develops a maximum load of 4064 tonnes.

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Problem 4

A first-order lever system is attached to the effort piston of the hydraulic system to allow the effort piston to be moved manually. If the maximum force that can be applied by hand is 1·2 kN, how long would the lever effort arm need to be if the load arm is 50 mm?

Diagram of creeper crane from Sydney Harbour Bridge
Eastern main baring, Milson's Point, resting on hydraulic jacks.
Photographer unknown, 21 October 1927. Sydney Harbour Bridge Photographic Albums 1923 - 1933, vol 4. State Records NSW.
Adjusting jack for releasing cables
Adjusting jack for releasing cables.
Photographer unknown, c 1930. Sydney Harbour Bridge Photographic Albums 1923–1933, vol 6, State Records NSW.

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For more information on hydraulics, go to NSW HSC online website.

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