Patent ID: 6009701
Filing Date: 2000-01-04
Classification: F01D,F02C,F04D,F05B,F05D,F16C

Abstract:
A ducted fan gas turbine engine having a longitudinal axis including a fixed structure, a propulsive fan mounted on a shaft, which shaft is normally coaxial with said engine longitudinal axis, a bearing structure, said fan shaft being radially supported by said bearing structure which is in turn supported from said fixed structure of said engine by radially frangible connection means, and restoration means to exert radial forces upon said fan shaft bearing support structure to substantially restore the coaxial relationship between said fan shaft and said engine longitudinal axis subsequent to any radial excursion of at least part of said fan shaft relative to said engine longitudinal axis following fracture of said frangible support means, said restoration means comprising first and second cooperating threaded members, one of said threaded members being externally threaded and the other being internally threaded, said first threaded member being mounted on said fan shaft bearing support structure coaxially with said fan shaft for rotational and axial motion relative to said support structure and said second threaded member being fixedly mounted on said fixed structure of said engine coaxially with said engine longitudinal axis, one of said threaded members having a shorter thread of generally constant diameter, the other having a longer thread of progressively decreasing diameter in a direction of said engine longitudinal axis, from a diameter greater than that of the other of said threaded members to a diameter substantially equal to that of the other of said threaded members, at least part of the thread of said threaded member having a shorter thread being axially aligned with the larger diameter portion of the thread of said other threaded member prior to said any radial excursion of at least part of said fan shaft.