Maximum allowable residual unbalance

Gear elements must be multiplane and dynamically balanced. Where keys are used in couplings, half keys must be in place. The maximum allowable unbalanced force at maximum continuous speed should not exceed 10% of static weight load on the journal. The maximum allowable residual unbalance in the plane of each journal is calculated using the following relationship... 

J.3.1 The maximum allowable residual unbalance per plane shall be determined from Table 5.2.2 of this standard. 

J.4.2.1 Select a trial weight and radius that will be equivalent to between one and two times the maximum allowable residual unbalance [that is, if is 1440 g mm (2 oz-in.), the trial weight should cause 1440-2880 g mm (2 oz-in.) of unbalance]. 

J.4.2.6 Repeat the steps described in J.4.2.1 through J.4.2.5 for each balance plane. If the specified maximum allowable residual unbalance has been exceeded in any balance plane, the rotor shall be balanced more precisely and checked again. If a correction is made in any balance plane, the residual unbalance check shall be repeated in all planes. 

W = Mass of journal (closest to this correction plane) Urpax = Maximum allowable residual unbalance =... 

The magnitude of the test unbalances should be such that the calculated maximum shaft displacement caused by the resultant total unbalance (residual plus test) is 150-200 percent of the allowable displacement from Tables 2.5 or 2.6 at the bearing probes, but shall not exceed eight times the maximum allowable rotor unbalance. 

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