Jack-up rigs are mobile offshore structure/platforms used for exploration and drilling of oil and gas deposits. These platforms are normally provided with three legs which extend through openings in a floatable hull of the jack-up rig. These legs are used to support the hull.
A typical leg of a jack-up rig has three mutually parallel chord members and each chord member is provided with a pair of opposing rack member that extend longitudinally along the length of the chords. The outward surfaces of the racks are provided with rack teeth, which engages respective teeth of the pinions carried by elevating jacking gearboxes.
Each leg is provided with jacking assemblies for moving the leg vertically with respect to the hull. As the legs are “jacked”, the hull is elevated or lowered.
I will discuss the jacking assemblies and the types of planetary gearboxes used in this unique application in my next blog post.
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