Shaft Support in Machinery: Bearings, Gears, and Couplings

1. Andrei Lozzi 2017 Most shafts are supported at 2 bearings. These bearings have to provide axial and radial support in a manner that does not over-constrain the shaft. That is, together they allow only one degree of freedom for the shaft, ie its rotation. Over-constraint may take place where 2 bearings may be set up to provide the same function. If proper tolerances are not provided such bearings may in fact provide a load for each other.

2. Large conveyor drive pulleys. This is our example for the analysis of a drive shaft

3. A hot hammer forged shaft blank, apparently intended to have integral gears or couplings at its end. The compressive residual stresses are useful in reducing tensile fatigue failures originating from its surface.

4. An older but still operational elevator drive, with worm gear box, and bronze plain slide bearing

5. Drive motor Inching gear drive for maintenance Grain elevator Thruster brake

6. Gear coupling. Necessary to allow acceptable alignment between the output shafts of the gear box to input shaft of the grain elevator These are guaranteed misalignments

7. A Cooper bearing, that is split horizontally, through inner and outer tracks, for ease of removal & replacement. A rare and expensive bearing.

8. 2 Dimensional misalignments In 2016 for the first time, we used the coupling shown here, in our steering In 3 Dimensions - from the CL of the steering wheel shaft, to the CL of the steering rack’s pinion, there are 5 independent degrees of freedom, that have to allowed for, exactly ! Two universal joints one sliding joint will do. But, for some USYD designers, all can be done with an adjustment in just 1 dimension (sarcasm) !

9. Even Gordon Murry an Englishman, for the McLaren F1 team understood the problem and the solution. Porscheknows how to do it In F1 $12000 is spent to save 1 kg (the Economist magazine).

10. The use of shaft mounted gearbox as shown here, have become very popular. This is largely because if the box and the shaft are not mounted separately their alignment is difficult to guarantee. The weight due to the box typically causes an insignificant increase in shaft stresses.

17. Since these are solid couplings, this is essentially a shaft mounted gear box

18. Locomotive drive motor and axle set. Note motor is fixed to chassis while wheel’s axle moves with the track. Ring gear coupling Pin and rubber coupling

19. An example of a shaft (or may be called hinge pin, even an axle) where shear stresses may be as significant as bending stresses.

20. Means of reducing bending moments and stress concentration where a shaft enters a boss or housing

21. In nearly all shafts deflection is closely constrained, yet there are instances where the shaft is designed to be rigid in torsion but not in bending. In some instances some specific bending is part of the shaft function, and allowed in its analysis.

22. Port Waratah & Korangang Island coal loaders A. lozzi 09

24. Australia is not short of coal deposits. Many years ago this island had high mountains and extensive forests. It looks like extreme storms washed and pushed large amount of vegetation down to what may have been the coast. There it was covered with sediment that excluded oxygen, forming over many years coal, gas and maybe oil.