If the crankshaft runout readings on the dial indicator are plus .002 inch and minus .003 inch, what is the runout?

To determine the runout of the crankshaft based on the dial indicator readings, it's essential to understand that runout is measured by finding the total variation in the surface of the crankshaft as it rotates.

In this scenario, one reading indicates a positive deviation of plus .002 inch, while the other indicates a negative deviation of minus .003 inch. To calculate the total runout, you need to find the difference between the maximum positive and maximum negative readings. This involves adding the absolute value of the negative reading to the positive reading:

• The maximum displacement from the center is .003 inch in the negative direction.

• The maximum displacement in the positive direction is .002 inch.

The total runout is determined by taking the absolute difference between these values, which mathematically results in:

Total Runout = .003 inch (negative maximum) + .002 inch (positive maximum) = .005 inch.

Thus, the correct runout reading reflects the total maximum deviation from the center, confirming that the answer is .005 inch. This figure represents the total allowable displacement that could impact the performance and balance of the crankshaft.