Small wind / Buyer questions
Mechanical interfaces
Can tightening a machine onto uneven feet change shaft alignment?
The short answer
Yes. If a machine foot does not contact its support as intended, tightening can distort or move the machine and alter its shaft position. A coupling adjustment can therefore appear correct before final mounting but change afterward. This is a support-contact problem as well as an alignment problem.
Distinguish offset from support distortion
The relative shaft position describes where the axes currently sit. Uneven foot contact describes how the machine is being supported and stressed. Adjusting one machine’s position can improve a shaft reading while leaving it distorted by its mounting. A thin foot, distorted base or trapped obstruction can produce different physical causes, so the term soft foot should not substitute for identifying the actual contact condition.
Keep measurement states comparable
Record whether the mounting is in its specified final condition when alignment is assessed. A reading taken with a different support or fastening state cannot automatically establish the installed shaft line. Repeated alignment movement after mounting changes should prompt review of the support assumptions rather than endless correction at the coupling. The equipment manufacturer’s method determines how support contact is checked; no loosening or shimming sequence is prescribed here.
Request support and alignment evidence together
Ask the generator or drivetrain supplier to identify acceptable foot contact, base flatness and the final state for alignment verification. SKF distinguishes soft-foot support conditions, while NSK emphasizes housing support accuracy; neither supplies a MARSTON mounting criterion. Release should establish that the mounted machine preserves its intended geometry and that the coupling displacement is acceptable in that state. An apparently good isolated alignment screenshot cannot prove that an unevenly supported machine will retain the same geometry. A base-contact issue can return when the machine is moved to another support. Retain the support condition with the alignment result rather than treat a factory-aligned assembly as independent of its installed mounting.
Sources
- KTR ROTEX instructions
- NSK shaft/housing design
- SKF: Soft-foot alignment tool instructions
- SKF bearing maintenance handbook
Examples are illustrative. Confirm product-specific performance, compatibility and supply scope in the applicable documents.