High Vibrations on Shaft Assembly

You might check the CMM specs for temperature range to see if you are operating within that range at all times....I would also check the shaft/spline for compatibility, clearance spec, grease for proper viscosity and temp specs, movement of any components under load, creep(mounting integrity)....

http://www.mitutoyo.com/news/resource-center/performance-of-cmms-testing-calibration-and-uncertainty/

Possibly imperfect dynamic balance of the shaft assemblies.

Is this a new problem? What has changed, if no.

What does your mechanical engineer say about this?

Have these shafts and the CMM test been successful in the past?

Details will help.

These shafts have been successful in the past. The lube is new and I'm checking into that. The spline adapters are new- the difference between the drawing and what was manufactured is that they have 2 extra teeth inside the ones we received but the FAA bought them off. This shaft assembly has an operating speed of 19,000 rpm.

The lube is different and the adapters do not comply to the drawing and you're asking the forum for help and there is no useful information provided by you?

Good luck with this.

I suggest that you hire an engineer, or do as 911 suggests.

with the little information available here, the change may effect and changed the shafts Natural Frequency and created a resonance. Or something else that you failed to mention or are unaware of (materials, welds,???) in the fabrication of this shaft...

Again, to drill it down, see post #5.

Welcome to CR4. We need more information about this whole scenario. Like, what RPM do these shafts rotate at? What are these shafts driving? How long are these shafts? How much clearance is allowed in the splined couplings? Are they first article, or in the R&D process? Are the support bearings rated for this "high speed" application? Do you have enough support bearings along the length? Are your * "Jesus nuts" properly torqued

The questions can be endless ......

Solar Eagle brought up some good points. As did Rixter about the dynamic balancing. And Lyn asking is this something new??

Unfortunately, CR4 doesn't offer video conferencing, so we're pretty much left with guessing what the possible causes are.

* Jesus nuts are the nuts that hold the rotating mass together, and first word out of someone mouth when shit hits the fan things start coming apart is, "Jesus, I should have double check the torque of that nut!"

This shaft transmits power to the aft transmission from the engine. It is 19.7" long, weight is 8 lbs and operates at 19,000 rpm. The assembly consists of the shaft, 1 internal splined adapter, a curvic tooth adapter, 2 plate assemblies an a coupling. The forward end of the shaft is attached to an engine coupling with bolts, a plate assembly and a coupling.

I suggest you bring in On-Site Rotating Apparatus Services specialists and have them analyze you situation. They may be able to zero in on the issues.

we had these people come for our alignment and balancing.

• Alignment
• DC Motor Brush Survey
• Sound Level Analysis
• Balancing
• Discharge Testing
• Ultrasonics
• Commutator and Slip Ring Profiling
• Predictive Maintenance & Other Services
• Vibration Analysis

But I'm sure there's one similar in your area.