Preparation:
• Ensure that the crankshaft is properly supported on v-blocks or bearings to allow free rotation.
Dial Indicators:
• Mount two dial indicators on a rigid surface (e.g., a surface plate) with their tips positioned close to the crankshaft journals.
• Place one dial indicator on the left side of the crankshaft and another on the right side, aligning them with the journal centerlines.
Rotating the Crankshaft:
• Slowly rotate the crankshaft by hand or using a turning tool.
• Observe the readings on both dial indicators as the crankshaft rotates.
Assessing Straightness:
• If both dial indicators show consistent readings throughout the rotation, the crankshaft is considered straight.
• If the dial indicators show significant variations in their readings, the crankshaft may be bent or not perfectly straight.
Measurements and Calculations:
• Record the maximum and minimum readings obtained from both dial indicators.
• Calculate the difference between the maximum and minimum readings for each dial indicator.
• The larger of these two differences represents the amount of crankshaft misalignment or bending.
Acceptable Tolerance:
• Compare the measured misalignment with the manufacturer's specified tolerance for crankshaft straightness.
• If the misalignment exceeds the specified tolerance, the crankshaft may require correction or replacement.
It's essential to follow the equipment manufacturer's instructions and use precise measurement tools to ensure accurate and reliable results when measuring crankshaft straightness. Additionally, experienced mechanics or technicians should perform this measurement to interpret the results correctly and take appropriate corrective actions if needed.
