1. Predictive Technologies PdM Techniques
Vibration Analysis
Predictive Technologies
PdM Techniques

2. Vibration and Alignment Specialist VibrAlign, Inc.
Richard Henry
Vibration and Alignment Specialist
VibrAlign, Inc.

3. Cardan Shaft Misalignment Identification
Cardan shafts (shafts with universal joints) are often neglected.

4. Cardan Shaft Alignment

5. Cardan Shaft Alignment Technical principle
Relative angular velocity

6. Cardan Shaft Alignment Technical principle
Degree of irregularity

7. Cardan Shaft Alignment Technical principle
Homokinetic operation is reached
by a second cardan joint

8. Cardan Shaft Alignment Technical principle

9. Benefits of cardan shaft alignment Vibrations
High wrap angle
Vibrations is transfered to gear box and motor

10. Benefits of cardan shaft alignment Why is it important?
Vital part in drives for process machines, breakage of cardan shafts causes down time.
Badly aligned cardan shafts set limitation in production capacity and product quality.
Stands for a considerable cost when repair is needed or a breakdown occurs.
Badly aligned cardan shafts reduces lifetime in gearboxes and motors.
Break down of a cardan shaft in running condition could be extremly dangerous.

11. Cardan Shaft Misalignment Typical vibration symptoms
Unbalance of the drive line (high 1X).
Drive line will not have the same center of rotation as the U-Joints.
High amplitude 2X and 4X driveline speed.
Torsional oscilliation

12. Cardan shaft alignment Measurement principle
Angular error

13. Cardan shaft alignment Tolerances
No standard, but…
Angular error within  0.25 mils/in
Offset within specifications.

14. Cardan shaft alignment Procedure - Coning
Coning -axis of rotation

15. Cardan shaft alignment Case story
Background:
A customer contracted VibrAlign to identify the source of an on-going U-Joint and Gearbox DE Bearing failure problem.
Reasons for the in depth analysis were:

16. Cardan shaft alignment Case story
High vibration level.
Axial bearing had to be changed every 8-10 week. Cost about $1500 every time.
Reduced production for about 10 hours at a cost about $1000/hour for each failure.
Necessary to have bearings in stock.
Problem with thermal expansion (high bearing temps).
No method to perform the alignment.

17. Cardan shaft alignment Case story
Vibralign arrived on site and collected initial vibration data. Vibration symptoms indicated severe cardan shaft misalignment.
Using a set of brackets specially designed to measure cardan shaft misalignment, we were able to identify an angular error of approximately 1.5 mils/inch of angularity in both the horizontal and vertical planes.

18. Cardan shaft alignment Case story
Vertical angular adjustments were made to the motor by shimming and the motor was repositioned horizontally.
The following spectra and waveforms clearly show an improvement to the operation of this machine.

19. Gearbox DE Vertical

20. Gearbox DE Vertical

21. Gearbox DE Horizontal

22. Gearbox DE Horizontal

23. Gearbox DE Axial

24. Gearbox DE Axial

25. Cardan shaft alignment Case story
Results:
Significant decreasing vibration level.
The alignment was performed in February -98 and no change of bearing in the gearbox has been done since then.
Increased production capacity.