Which term describes axial movement between rotating parts along the shaft?

• A. End Float
• B. Run-out
• C. Vibration
• D. Alignment

Answer: (A)

End float is the axial movement of a shaft relative to rotating parts along the shaft’s axis. It comes from the clearances in bearings and between components like gears, spacers, or pulleys. This axial play can be positive (the shaft can slide in an axial direction) or kept to a minimal, controlled amount by design. Controlling end float is important because excessive axial movement can affect gear meshing, cause oil leaks, change bearing preload, or lead to misalignment under load.

Run-out describes radial deviation of a rotating surface, not movement along the shaft. Vibration is a broader dynamic motion often caused by imbalance or misalignment. Alignment refers to lining up shaft axes, not the axial movement between parts. So the term that describes axial movement along the shaft is end float.