How do I find that the motor shaft and the pump shaft are not in a straight line?
Concentricity is the deviation of the core diameter from the entire center of the circle. The ideal state is 0, which is not offset. But actually there are offsets. General single-mode PC concentricity below 1, is considered a relatively good product.
The coaxiality is the location tolerance, and the correct position is the reference axis. Because of the measured point on the axis of different datum axis may appear in each direction, so the tolerance zone is a reference axis as the axis of the cylinder, the tolerances for the diameter of the cylinder, before filling the symbol "value in tolerance".
If the unit is oscillating and vibrating, the motor shaft and pump shaft are not in a straight line (concentricity of the unit).