Page 70 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment
P. 70
Rotating Machinery: Practical Solutions
3.5 Mils @ 60°
0
30
330
60
300
90
270
240 120
210 150
180
1/2 Mil per Division
Figure 5-1. Graphical Solution with Original Vibration Plotted
1. The trial weight could be added exactly on the heavy spot. If
so, the vibration amplitude would increase, but the reference
mark would remain in the same location. To balance the ro-
tor, the trial weight would simply be moved 180 degrees and
adjusted in mass until the rotor was balanced.
2. The trial weight could be placed in exactly the correct posi-
tion, 180 degrees away from the heavy spot. In this case, if
the trial weight were smaller than the heavy spot, the vibra-
tion amplitude would decrease, while the reference mark
would remain fixed. Again, the mass of the trial weight
would be altered until the rotor was balanced. However, if
the trial weight were heavier than the heavy spot, the refer-
ence mark would shift 180 degrees. The mass of the trial
weight need only be reduced until a satisfactory balance was
achieved.
