Check the horizontal radial runout and vertical radial runout of the piston rod during the reciprocating movement of the piston of each stage to check the comprehensive maintenance effect of the moving mechanism.
Measuring the amount of runout in the vertical direction: A dial is mounted at the top of the piston rod at 12 o'clock and abuts against the pressurized packing. The needle of the disc must be perpendicular to the rod shaft. Measure the amount of runout in the horizontal direction: the dial is placed at the 3 or 9 o'clock position of the piston rod against the pressure-bearing sealing packing, depending on the "closeness" as close as possible.
The connection between the piston rod and the crosshead must be properly tensioned and the crosshead must be flat on the glide path and evenly fitted. Between the sliding track and the slide, the two ends should not be inserted into the gap of 0.04 mm at 6 o'clock, and the gap inserted in the four corner plugs of the glide path should be uniform.
Press the “pinch” on the dial to make the pointer on the dial turn one turn, so that the pointer is aligned with the zero mark on the disc. The compressor is rotated 180° to move the piston from the fuselage end to the cylinder end. During this 180° displacement, the resulting reading, whether positive or negative, is the total runout and is recorded.
In order to verify the correctness of the reading, the compressor is then rotated 180° (one turn in the same direction) to return to the initial position of the crankshaft. The pointer on the disc should still be zero, otherwise the gauge should be moved and the measuring step should be redone.