Before installing a flexible coupling you should check for __________.

• A. Run out
• B. Alignment
• C. Torque
• D. Fit

Answer: (A)

Before installing a flexible coupling, you want to verify runout. Runout is the deviation of the shaft from a true circle as it rotates. If there’s significant runout, the coupling will experience wobble with every revolution, which can cause vibration, uneven loading on bearings, premature wear of seals, and fatigue of the coupling’s flexible element. Measuring runout—often with a dial indicator near the coupling face—lets you confirm the shaft is true and within tolerance before assembly. Once runout is within spec, you can proceed to check alignment and other factors. Torque and fit matter, but they don’t address the dynamic wobble that runout represents, which is why runout is the key precaution here.