Lift boats or Jack up oil rigs are essential for the oil and gas industry. One offshore jacking system is pinion and rack to elevate legs and hull in operation. It is well known that rack and pinion of such applications exceed the permissible contact stress by the factor of 2 to 5. The design and evaluation of such systems is still a technical challenge. The pinion will be typically highly modified and analyzed based on the Hertzian contact stress theory of two cylinders in contact. This method will show how to start with a basic rack and pinion design. The true involute profile of the pinion will be replaced with a multi radii profile. In a second step, the pinion design will be analytical optimized to reduce the contact stress and improve the life expectation. The influence of major gear parameter such as module, profile shift coefficient as well as the pressure angle will be analyzed and explained. The results of the final pinion will be compared with an existing pinion design to evaluate and discuss a reuse of existing hardware. The results of the final designs will be verified by a numerical method. This paper demonstrates the impact of major gear parameters for a pinion design and their impact on the life expectation. The benefit of a custom pinion design and how much improvement can be achieved with emphasizing the design process properly will be shown. Furthermore it shall serve as a guideline for best practice to design a rack and pinion for offshore jacking applications.
ISBN: 978-1-64353-006-2Pages: 13Author: Adrian Nowoisky
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