aligning pumps

[harryjacko]

Hi All, we have a very old mather & platt 6 stage centifugal pump ( from 1946 )that runs at 3000 rpm, the medium is aviation fuel and the pump is driven by an electric motor the other side of a blast wall. Inbetween the pump and motor is a jackshaft supported either side of the wall by a pedestal containing a roller bearing. The pump has been out for refurb. and is now going back in, the jackshaft has been out and had new bearings, now do i line the motor coupling to jackshaft coupling then jackshaft to pump, or leave jackshaft out and line the pump and motor then add jackshaft? . . . . any advice would be welcome, ...... Harry

 

[JJPellin]

What are the flexible elements on the ends of the jack-shaft? Single flex-planes such as a disk pack or diaphragm? A full flexible coupling that can take offset and angular misalignment? With very limited information, I would align the pump to the motor first. Then I would install the jack-shaft. Then I would measure the alignment on both ends of the jack-shaft (jack-shaft to pump, jack-shaft to motor) and tweak those alignment until they were in spec.

Johnny Pellin

 

[Compositepro]

There are numerous methods to align shafts, including using lasers. The method often depends on the tools available or the obstacles in the way. It is something best left to skilled tradesmen to do. Obviously, the objective is to get the axes of all the shafts to be on one straight line. The required accuracy of alignment depends of how stiff the shafts and bearings are and what king of couplings are used. Some couplings are designed to allow for a large amount of misalignment.

 

[desertfox]

Hi

Some pictures might help but what I would is put the pump back complete with jack shaft and without completely tightening the pump down I would put a clock at motor and pump end and then turn them be hand if that's possible.
I would them move the pump so that the readings on both clocks was as close to zero as possible.


“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[spciesla]

Compositepro,

Although many couplings are designed to allow for a large amount of misalignment, the equipment attached to the couplings are not. I would not use the alignment tolerances (allowed misalignment) associated with the couplings.

Alignment tolerances are generally related to operating speed and the type of coupling (short, spacer, etc.).

Sites like

http://www.ludeca.com

or

http://www.vibralign.com

have plenty of relevant information.

 

[LittleInch]

It depends to a certain extent on the movement available in each part.

I have a nasty feeling I've seen this pump house, but maybe it was a similar one. Pity you didn't just replace the motor and pump and knock the wall down....

I would try and line up the pump and motor first by laser level / dial gauges the fit the shaft.

If that is not possible start with the item most fixed (probably the pump and work away from there.

Will be some iterative adjustments as the connections get added.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[harryjacko]

Hi guys, thanks for all your comments, the couplings are 12inch in dia and 2.5 inch thick, have four coupling bolts with rubber bush inserts, really old fashioned !! the pump company who have refurbed the pump rekon they need the jackshaft removing so they can laser line the motor to the pump then re-install the jackshaft, i would have thought everything would be better off lining in situ starting from motor to jackshaft then jackshaft to pump, i will try and add a drawing i have done of the set up

 

[LittleInch]

Yup, seen this before - Go with the pump vendor - your shaft needs to be as close as possible to dead straight pump to motor first.

Otherwise you could easily run out of adjustment room on either the pump, motor or the pedastal bearing.

Fix the two big things which don't move level in all axes then connect the shaft.

Better still knock the wall down and fit a modern motor and pump able to stand zone 1 on a single skid....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.