Home Forums General Discussion Technical Questions Vibration

Hello,

I hope someone out there has some ideas on a problem we are having on a newly modernized duplex. The OEM is Otis/Beckett using an overhead 22CT machine roped 1:1, no deflector. Speed is 350 Ft/min, Capacity 2500 LBS, empty car weight 3300 LBS, there are 4 5/8" ropes and 22 stops, whisper flex compensation. The controller we installed is MCE M4000 using the KEB drive and new Reuland motor. We retained the machine. We replaced hoist ropes, compensation (was chain), slipper guides with Elsco rollers on the car and cwt.

The issue we are having is a vibration that you can feel in your feet throughout the travel of the car. It seems like rope vibration so we isolated the hitch plate but it made no difference. We checked roller guides but we cannot figure out the source. The machine seems ok and we tried adjusting drive gains but again no difference. Both cars have the same problem. When there is 500 LBS or more in the car there is a dramatic improvement. The sling is made out of formed steel similar to Dover design.

Any ideas would be welcome!

When you say your are using a new motor, did you fit this into the 22ct frame? Why? Or did you replace it whole?

It sounds like you may be getting a ripple voltage thru the drive output, considering when you add weight it seems more a balanced output.

You need to find out if you have a Mechanical or Electrical problem. You can put an accelerometer in the car and drift it to see if the problem is Mechanical. You can beat your head against the wall trying to take a mechanical problem out with Electrical Adjustments.

Here are a few more places to look...

How do your isolation & tie down pads look?
Is there any debris between the bed plate and machine beam?
Are the bolts to the tie downs & isolation pads installed correctly?
If you back off spring tension one roller at at time on the rail guides is there any change?
Did you change the ropes?
Is the vibration different in opposite directions?
Are the new compensation chain the same weight as the old chains?

Also, Can you post a picture of the motor mounted to the machine?

Thanks for comments

Hoist ropes have been replaced both cars. The original motor was DC and was replaced with a flange mounted Reuland AC. There does not appear to be vibration at the machine, only felt in the car. I will be going back to site to take another look. We did re-adjust roller guides to minimum spring pressure. Vibration is fairly constant in both directions and feels as though it is coming up from the platform. We may look at replacing platform isolation rubber next .... I will try the drifting method to rule out electrical - a good idea.

Thanks again for everyones input!

Did you install an isolating coupling between the motor and brake drum. We did a duplex with 22ct machines and Rueland motors and had to put one in for vibrations.

We removed the coupling from the DC motor and used it on the AC motor but with new pins and bushings.

I would add, have you maintained the same car to cwt ratio? Also have you tried to refit the old chains to see the effect?

I would imagine if you placed a half full water bottle on the floor of the car you can see the vibration transferred to the water. If you placed the bottle on the top of your sling I'm betting you will see is as well.

For science, I recommend placing the bottle on the equipment at different points (motor, gear box, brake, machine beam, you could even tape it to the ropes). It's not sophisticated but it is effective.

I'm leaning toward the machine vibration transferring through the ropes. If it is I would check the motor alignment, thrust, brake & and root clearance.

Let us know how you make out...

A few more idea's. How are the velocity and position encoders mounted. a bad mount , especially on the velocity encoder will transfer vibrations. also I agree with jkh, about Machine vibration. Were you able to tram the new motor to the Brake pulley. Think of it as 2 circles, one inside the other, if they are not perfectly even around the whole circumference, vibration will occur. Lastly we always used a nylon isolation between the Motor pulley and the Brake pulley on a MOD.

If your problem does not end up being electrical, I would tension hoist ropes and check for car sling to cab isolation.

Is the wisperflex going through rollers? If so take them out of the equation, just to rule them out. I had bad rollers shake things pretty bad before.

Thanks for everyone's input. I wrongly stated that compensating chain existed originally. Even though 22 floors, there were no comp chains before. We added two whisper flex WF20 per counterweight and shallow pit guides. We tried drifting the empty car and the vibration could be felt as the speed approached 350. So it does seem like a mechanical problem. There is rubber isolation between the platform and the sling, but how effective it is I do not know. It is interesting about the comment made in regards to whisper flex rollers. I am wondering if this could be the source. We will try running without guides and see if that makes a difference. Also I like the idea of the half full water bottle. Will definitely try that out. I appreciate all the input.

John Jay is on the mark. You now know you have a mechanical vibration we will not do a mod without the nylon insulator.

Another idea; years ago we had the same problem on a 1000 FPM car in Seattle. Drove us nuts, we did everything you guys mentioned above to no avail. Finally one of the Brighter Bulbs among us (you know a guy that doesn't have that blank look on his face typical of most elevator men) Guess the word he used was "Harmonics" It was combination of several things. His fix was to bolt a flame cut cwt filler on angles attached to the bottom of the Xhead. To give you an idea of the set-up. You could sit on the filler and operate the permit ally mounted car top inspection station. He moved the filler in and out until the vibration disappeared. Know it sounds kinda hokey but it worked.

Work Safe All

Jim,
Let me know when the first printing of you book hit the shelf! I can't wait...

JKH,

It's out and available thru Amazon

http://www.amazon.com/Elevator-Man-Stories-Years-Trade/dp/1453692282

Or "The Elevator World Book Store.

Enjoy,

Jim

Got it...

Im looking forward to reading it.

Curious if the cars have been static balanced, when extra weight is placed in car the vibration is better? Compensation whisper flexes have been added? Thrust bearings ? with new machines on old gearbox And yes agree with encoder mounting must be aligned perfectly other wise the drive will amplify vibration. Just a thought.

Really? Everyone has a job to do and no one spoke is more important to the wheel than the next.