Categories: Shaft Alignment,Machinery Diagnostics,Machinery Maintenance,Other Topics

A “Typical – Atypical” Alignment

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By on October 7, 2020

A colleague and client of ours called, in a bit of a quandary.

“Ever seen anything like this?” he asked.  I had to answer “No, I have not”.

This is a C-face motor.  It is typically mounted to a C-face flange, which connects to a vertically oriented pump.  But in this case, the C-face motor is mounted to a steel plate, and the pump is a vertically oriented “horizontal” split case pump.

The customer inspected the machine, including an alignment check. Their findings?

  • The coupling insert was shredded and replaced.
  • The shafts were out of alignment by approximately ⅛”
  • The pump bearings were bad and had been replaced recently.


There was not enough clearance in the motor hold down bolt holes to correct the misalignment. Both the suction and discharge flanges of the pump were opened, and there were flex joints on both the suction and discharge sides. This allowed both the motor and pump to be moved.

And now you know as much about it as I do.  So, this blog comes with two questions:

  1. How would you perform this alignment?
  2. Do you see any other potential issues with this design?

I’m very interested in your thoughts.

About the Author

Stan Riddle joined VibrAlign in 2008. He has over 35 years experience in aligning industrial machinery. Stan received his AAS Degree in Machinist Technology from Surry Community College in Dobson, NC, and also holds a diploma in Industrial Systems Technology from Forsyth Technical Community College in Winston-Salem, NC, where he was also an instructor in the program.

Stan began his maintenance career working as a machinist and millwright for companies such as Weyerhaeuser, R.J. Reynolds, and Tyco Electronics. He also has over 25 years experience in Predictive Technologies, such as vibration analysis, thermography, oil analysis, and ultrasonic inspection. He is a certified Level III Vibration Analyst with the Vibration Institute, and is a Past Chairman and Board Member of the Piedmont Chapter.

Stan and his wife live in Yadkinville, NC.

One response to “A “Typical – Atypical” Alignment”

  1. Edwin says:

    Hi Stan, kindly allow me to share. This is treated to be vertical alignment process. It can be aligned uncoupled to facilitate shaft rotation during execution of alignment. Before performing the alignment, there are parameters to look at as identified (as found) such as neck-down the hold down bolts, but this is risky since the cross-sectional area of non-threaded portion of the bolt will get smaller. Enlarging the hold down bolts’ holes while maintaining the bolt-circle diameter (BCD). Provide jack bolts to be located in each hold down bolt (at the flange side). In regard to design issues (since the owner wanted it to be like that) each shaft can be inserted with a bush to act like an adapter to reduce the cantilever effect or change a coupling type with longer and bigger hubs.

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