Here is a hoffman type blower. The 100 HP motor fails every 2 years despite precision alignment and allowing for thermal expansion.

Hoffman.avi (4,336 KB, 193 downloads) Hoffman Type Blower

How to view: right click and save as to download the AVI file. You can then play it in your mediaplayer.

Jon - so what did the movie show us? There is obviously a great deal of movement and it looks like a mounting is broken.

Thanks a lot for posting this.

Terry O

The problem is structural weakness as shown by the motor support's deflection.
One picture is worth a thousand words when trying to get work done.
This machine hasn't been fixed, yet. The solution requested is a gusset in each of the motor support corners.
This is a good example of the simple graphics you can draw and still get the results needed.
Instead of drawing the motor and fan, only the feet and shafts are shown.
The dots show where measurements were made. If smoother animation is needed, more measurement points can be added. If they are measured, a finer resolution is produced. If they are not measured, the program can interpolate between two measured points to assign a formula to the non-measured point (menu option).

Jon,
Is that support box under the motor bent in the shape of a 'U'? No wonder. Great data!

Hi Ron,
Yes, the support is sheet metal formed into a "U". The bends are not quite 90˚, however. The static view shows the correct angle since this is important. Can another possible problem be seen in the animation?

This message has been edited. Last edited by: Jon McFadden,

Hi Joh,

I notice you have a constraints problem with the motor feet and the plate they attach to.
(The feet rise above and fall below the plate.)

I have been using a B&K system and having put in the constraint equations for a similar situation, is does not apply them.

I'm wondering if I have to "Group" the feet and the plate before they work ?

Any thoughts ?

Cheers

John Morey

Hi John,
In this case, I used the same values for the feet, instead of getting discrete readings for each of the 4 corners. To clarify, the front left foot used the reading for #5, the rear left foot used reading #6, the right rear used the reading for #7 and the right front foot used the reading for #8. That is why there is no distortion to any of the motor feet. Access to all four corners of each foot was not possible.
If the feet were moving out of sync with the base, I would be checking for a soft foot condition.
I use grouping to simplify hiding different parts of the machine. Lines and surfaces are there to make the graphic easier to view. The vibration data is assigned to points only.
The condition that I hoped someone would notice is the possible mode shape between the feet. The node is where I proposed to place the gussets. A post between the anti-node and the base would be much better.

This message has been edited. Last edited by: Jon McFadden,