The Mobile self-elevating platform have either a triangular or quadruple shaped self-contained platform, equipped with three or four electromechanically powered legs. The platform is towed to the drilling location in floating mode. Its legs are then lowered to the ocean floor, and the platform hull is elevated above the wave action.

The jacking system and holding mechanism on self-elevating units are to be designed and constructed with sufficient redundancy so that upon failure of any one component, the system will prevent an uncontrolled descent of the unit. This is to be accomplished either by continuing to jack to a safe position or holding in place. Approved procedures are to be provided to allow emergency raising or lowering of the unit after failure in the case the unit is holding in an unsafe position.

Jacking systems are to be considered as machinery to provide the vertical movement of the legs as well as structural elements transmitting the loads between hull and legs, as applicable to the particular system design.

Now, here we are going to design for Rack and Pinion Jacking Gear Train as per below figure which showing Rack and Pinion Jacking System

A jacking system using climbing pinions, most commonly driven by electric or hydraulic motors through a jacking gearbox, to engage with racks attached to the 8 legs of the unit in order to raise or lower the hull in relation to the legs in the elevated condition or to raise or lower the legs in relation to the hull in the afloat condition.

The gear train assemblies of Rack & Pinion Jacking system located at each chord of the legs are collectively referred to as the ¼” Pitch gear (Climbing Pinion) unit assembly. Each unit basically consists of a guide structure, 4 each AC motors with brakes, 4 each primary gearboxes, 4 each Secondary gear structures with drive pinions, and 4 each primary gear structure with drive pinions.