Vertical Vertigo - little known change causes headaches
"Hollo-Shaft Horrors"
Vertical Hollo-Shaft Motors in the 150Hp and above built on the 444 Frame size have "an issue". Gone are the easy days when you could merely count on matching the frame size, horsepower, and speed to replace your pump drive motor.
We've come to learn (the hard way), that the premiere Vertical Hollo-Shaft manufacturer - US Motors, has made a serious change in a dimension critical to the pump head shaft (shaft that connects the motor to the pump impeller(s)).
Referring to the dimension drawing examples to the right, pay attention to the "CD" dimension differences between the "OLD 444 frame" and the "NEW H444 frame".
As you can see, there now is a dimensional difference which effects the pump head shaft. In the examples to the right, the NEW 444 frame is 2.28 inches longer in the area where the head shaft locknut threads would normally have been protruding to screw the locknut onto. Sometimes the CD dimension is shorter on the NEW style motor replacement.
Possible solutions are: 1) machine the coupling down to allow the headshaft to have enough threads exposed for the headshaft locknut 2) place a spacer plate between the pump base and the motor base 3) add washers on the locknut to allow enough threads to protrude for impeller adjustment 4) machine a new headshaft 5) machine down the locknut to get more adjustment
Just be aware and plan for the differences that the new Vertical Hollo-Shaft designs will cause when you go to adjust your impeller/pump bowl clearances via the head shaft locknut when replacing 150Hp and above.
If you need help with this issue, please call us at (800) 808-1870 or email sales@Reed-Electric.com
