View Full Version : Tips Requested for Aligning Shafts to be Concentric

07-13-2010, 10:25 PM
I have a coolant system that will be ready to reassemble in the near
future and I would like to align the motor and pump shafts to be as
concentric as is reasonable to expect.

A 'Before' shot shows that the coupler carries a fan blade for cooling.


The pump is supported by hose barbs that pass through grommets in
vertical stand-offs made of thin (16 ga?) flat stock. The supply and
return hoses in the picture (above and below the pump on the left side
of the fan) attach to the hose barbs - the flat stock & grommet mounts
are visible here.

How would one go about assessing concentricity between the motor
and pump in this instance? With such a mounting system, is there
sufficient self-aligning capacity that adjusting for concentricity is
a matter of diminishing returns ?



07-13-2010, 10:49 PM
If there is or you can make room?, clearly, that is a perfect candidate for other then a solid coupling, check out Love Joy couplings or flexable couplings.

Other then that, one must position and/or shim as required.


07-13-2010, 10:54 PM
The cooler is pretty agricultural in design by today's standards and shimming
will be simple to do.

I suppose one approach is to mount the pump with the coupler and then
swivel/raise/lower either side of the standoffs until the barbs float around
evenly in the grommets.


07-13-2010, 10:59 PM
That's an odd setup,looks to require the support of the motor shaft to work.Might be a canidate for fix whats there.

07-13-2010, 11:11 PM
It is a 3-1/2-point support system: two stand-offs, the motor shaft and
a pressure relief tube.

The end of the pump (left side of image) extends into a hollow in the center
of the cooling coil but makes no contact with the coil. A tube exits the
pressure relief mechanism at the (left) end of the pump and snakes back
through the cooler coil hollow, and over to the reservoir - this tube can
be seen beside the upper coolant return hose. While I doubt the relief
line contributes much support, it does provide some.

As you said, fix what is there.

What I was wondering was how to size up the alignment - such as it may

Mocking the parts up, excluding the coupler, and then somehow evaluating
the relative positions of the two shafts is what I had in mind.


07-13-2010, 11:16 PM
I suppose a 6" steel rule or equivalent along one or the other shaft
with visuals taken at various points of the compass would provide
a base alignment.


07-13-2010, 11:41 PM
From what I can see in the photo there is nothing to line up. It looks to me the coupler slips on the motor shaft and the pump shaft slips in the other end of the coupler with the fan mounted on the coupler. The grommets and standoff's are only to keep the pump from freely spinning when the motor is running.

If the pump were mounted solid then you would have to shim the pump and/or motor to align the shafts.

07-14-2010, 12:38 AM
The pump standoffs appear to be marginal at best . It appears to be a solid or rigid coupling. Are we correct on that?
Alignments are normally done with the coupling unbolted or otherwise disengaged. The most common method is rim and face, where one indicator is riding on the OD and one on the face of the coupling. Obviously there is no room here for any kind of instrumentation. The shafts can be "Gross Aligned with a straight edge if the same size or straightedge and caliper if not. I would put some more substantial pump mounts, gross align and use the Lovejoy coupling which will easily tolerate.030" on this kind of installation.
But , curious, what are you cooling? If this is for a machine tool coolant throw out all that stuff and mount a pedestal or submersible pump in a sump with 2 chambers, one for settling and one to eliminate floating material. That's all you need.

07-14-2010, 01:18 AM
As CarlD suggests, the principal function of the standoffs is probably
to restrain the pump from rotating.

Yes, the coupling is solid. Set screws at each end lock the shafts
to the collar.

This is a Radiator-1 tig torch cooler. Mine is a Canox but it is a merely
a rebranded Miller for the Canadian market. What is pictured is how the
cooler was designed by or for Miller. I'd like to use it as built for a while
rather than reengineer the mounts, coupling and fan installation straight

Thanks for the comments. The discussion has helped me see the
mounting in a different light. I think I can get to where I want to be
with the benefit of the insights and suggestions offered.


07-14-2010, 06:32 AM
Next time you see a truck mudflap laying on the side of the road stop and pick it up. They are perfect material for making flexible mounts and couplings. For that unit I would replace the two sheet metal supports with a couple of similarly sized 1/4" thick mudflap material. Just make a hole in each piece to pass the fitting through. Cut the sheet metal tabs off short and bolt the mudflap tabs to the ends. It will run quieter.

07-14-2010, 07:29 AM
How about a Climax instant split coupling?It will replace what you have and as long as both shafts run true alignment shouldn't be an issue.