How to calculate and eliminate the radial and axial deviations when the flywheel sinks during the alignment of a reciprocating compressor

I. Deviation measurement and recording: Mark the couplings. On the outer circles of the two adjacent halves of the coupler, make marks every 90° around the circumference to prevent misalignment during alignment and ensure accurate readings. Install the dial indicator by fixing the magnetic gauge base on the coupling side of the drive shaft (such as the motor shaft) or the driven shaft (such as the compressor shaft). Install a radial dial indicator (to measure the radial runout of the shaft) and an axial dial indicator (to measure the axial displacement of the shaft), ensure that the pointers are perpendicular to the coupling face, and zero the readings of the dial indicators. The master and slave shafts are rotated synchronously at a slow pace of 360° in the direction of rotation. The readings taken by the radial and axial gauges at the positions of 0°, 90°, 180°, and 270° are recorded as follows: Radial readings: a1, a2, a3, a4; Axial readings: b1, b2, b3, b4. To verify the validity of these readings, it is necessary that a1 + a3 = a2 + a4 and b1 + b3 = b2 + b4. The error should generally not exceed 0.02 mm. If it does not meet the requirements, the cause must be identified (such as a loose dial indicator or an axis that cannot rotate freely) and re-measurement should be carried out. II. Deviation calculation and result analysis: If Δa is positive above and below, it indicates that the driven shaft is displaced above the driving shaft ； If Δa is 0 above and below, it indicates that the driven shaft is open at the top (i.e., the axial clearance increases) ； If Δb is up or down