Complex shaft/bearing analysis for power-shift transmissions
01 April 2006
Recently, transmission engineers have been considering some unusual shaft/bearing arrangements for a new generation of gearboxes. The new arrangements presented such a challenge to traditional analysis methods and tools that some of the bearing manufacturers involved approached Romax Technology for some help and advice. Using the novel analysis capabilities of RomaxDesigner, these arrangements were modelled and analysed in less than a day.
The study considered two concentric shafts connected via one thrust and two radial needle roller bearings. The analysis had to take into account the elastic deflections of all the components, the radial internal clearance (RIC) of the two radial needle roller bearings and the pre-load of the tapered roller bearings that support the shafts.
The analysis showed that the thrust needle roller bearing became overloaded due to a 'pinching' action induced by the bending of the shafts and the deflections of the other bearings. Moreover, the life of the thrust needle roller bearing was found to be dependent on the behaviour of the other bearings. Its life dropped by 50% as RIC was applied to the two radial needle roller bearings. Changing the pre-load/end-play of the tapered roller bearings also had a dramatic effect on the life of the thrust needle roller
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