| 摘要 |
The invention relates to a drive system, in particular a downhole drilling assembly ( 10 ). In the preferred embodiment, a bearing mechanism ( 14,24 ) of the assembly ( 10 ) is isolated from a gear mechanism ( 20 ) of the assembly ( 10 ), to prevent failure of the bearing mechanism ( 14, 24 ) due to vibration and heat generated by the gear mechanism ( 20 ) in use. A lower bearing unit ( 24 ) of the bearing mechanism ( 24 ) is coupled to the gear mechanism ( 20 ) by a shock eliminating coupling assembly ( 22 ), which prevents the transmission of shock loads to the gear mechanism ( 20 ). Also, the gear mechanism ( 20 ) is coupled through a shock eliminating coupling assembly ( 18 ) to a turbine ( 16 ) and thus to an upper bearing unit ( 14 ). Sealing assemblies ( 60, 116 ) are provided for the gear mechanism ( 20 ) and the upper bearing unit ( 14 ) to prevent drilling fluid ingress and consequent damage. The assembly ( 10 ) may also carry a torsionally flexible drive shaft ( 46 ).
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