February 7, 2012
Align a Cooling Tower in Under an Hour
By Stan Riddle
Aligning cooling towers with spacer shafts can sometimes present a challenge. We recently provided alignment training and assistance to the HVAC Group at the Federal Reserve Bank in Richmond, VA.
This was a Marley cooling tower, with a 60 HP motor, connected to the gearbox by a 48″ spacer shaft.
That’s me, the trainer, inside the fan. The mechanics are using their Fixturlaser XA, and telling me how to shim up their gearbox. How often do you get that from a trainer?
The motor had recently been changed to an inverter-duty motor, in preparation for installing variable speed drives on this tower.
The initial measurements showed that the motor was sitting about 1/8″ too high. There were no shims under the motor, so it could not be easily lowered.
Using Live Mode, and employing the Verti-Zontal process, we shimmed the gearbox up vertically to correct a base-bound problem, twisted it horizontally a bit to correct a bolt-bound problem on the motor, and completed vertical shimming of the motor to align it to the gearbox.
Total time to align – 22 minutes!
Align a cooling tower – in under an hour? That’s Verti-Zontal power!
What is the alignment procedure for Marley Gear reducer, model 2200 and fan blades correct positioning
Rodney, thanks for dropping in! I can’t speak for Marley, but I found several references online for their alignment specs. Does your tower use a spacer shaft? If so, their tolerance is pretty forgiving. Our tolerances are based on rpm. With a 1785 input speed from the motor, we would align to 4 mils offset, and .7 mils per inch angularity, regardless of whether it uses a spacer shaft or not. This is easy to achieve with one of our laser tools.
As to correct fan blade positioning, do you mean blade pitch, or clearance around the plenum, or fan shroud? Your local Marley rep could also answer that better than I could. Normally, pitch is set with inclinometers and an amp meter, to get maximum air movement without tripping the motor. Tip clearance is usually just an even amount for each blade.
I hope this helps a little. If VibrAlign can help out with any alignment-specific questions, or for the number of your local VibrAlign rep., please let me know. Thanks again!