Tham khảo tài liệu 'handbook of shaft alignment part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 270 Shaft Alignment Handbook Third Edition FIGURE Observe the amount of sag on the dial indicator as you rotate the assembly to the six o clock position. To compensate for the sag add the amount of the sag observed at the bottom to each bottom reading and the amount of the sag observed on the each side to each side reading FIGURE Mathematically compensating for sag. Shaft Alignment Measuring Tools 271 When the motor and fan shafts are perfectly aligned you should have these field readings Motor Fan FIGURE Ideal shoot-for readings assuming no OL2R movement occurs . that the centerline of rotation of the spindle and chuck is perfectly in line with the centerline of rotation of the live center. ZERO SAG BRACKETS Is it possible to defy gravity and construct a cantilevered beam that compensates for the elastic bending due to the force of gravity You bet within limits. Figure shows a bracket design where a second span bar holds a weight so that its position is on the opposite side of the clamping point on the shaft thereby counterbalancing the overhung weight. Figure shows another arrangement for long spans where a different type of counterweight is placed on a coupling spool that lifts the span bar. Neither of these prototype anti-sag devices are included in any of the dial indicator based alignment measurement systems. Another long span bracket system fabricated from lightweight carbon tubes is shown in Figure . FIGURE Xmas tree bracket. 272 Shaft Alignment Handbook Third Edition Plate steel Xmas tree bracket bolt Sch. 80 pipe support on roller stands FIGURE How to measure sag when using an Xmas tree bracket. DIAL INDICATOR SHAFT ALIGNMENT SYSTEM MANUFACTURERS The ensuing pages cover the currently available dial indicator based shaft alignment systems. There are currently 7 manufacturers offering 19 different models. A talented person could fabricate his own shaft alignment fixtures purchase dial indicators and perform .
