Unless otherwise specified, couplings shall be component balanced. Each component, such as the hubs, sleeves, flexible elements, shims, spacer, and adapter plates, shall be balanced individually. All machining of components, except for the keyways of single-key hubs, shall be completed before balancing. Two-plane balancing is preferred, but single-plane balancing may be used for components with a short axial length. Each component shall be balanced so that the level of residual unbalance for each plane does not exceed the greatest value determined by the following expressions:
U = 4W/N
U = 0.0008W
U = 0.01
In SI Units,
U = 6350W/N
U = 50.8W
U = 7.2
Where:
U = Residual unbalance, in ounce-inches
(gram Millimeters)
W = Weight of the component, in pounds (kilograms),
apportioned to the balance planes so that the sum
of the weight apportionment for both planes equals
the total weight of the component.
N = Maximum continuous operating speed,
In revolutions per minute.
1 When specifiedm residual unbalance checks shall be performed on components of couplings with maximum continuous speeds of 5000 revolutions per minute or greater. These residual unbalance checks shall be performed after balancing is complete and before the component is removed from the balancing machine.
2 Unless otherwise specified, couplings balanced in accordance with the above shall be assembled and the balance verified. The residual unbalance for the randomly assembled coupling shall not exceed the greatest value determined by the followin expressions:
U = 40W/N
U = 0.008W
U = 0.1
In SI Units,
U = 63,500W/N
U = 0.8W
U = 72.0
Where:
U = Residual unbalance, in ounce-inches
(gram Millimeters)
W = Weight of the coupling, in pounds (kilograms),
apportioned to the balance planes at the two coupling
hubs so that the sum of the weight apportionment
equals the total weight of the coupling.
N = Maximum continuous operating speed,
In revolutions per minute.
Couplings that fail to meet these criteria shall be balance corrected by repeating the component balance, not by trim balancing the assembly.
Sample plot and calculation of Resiudal Unbalance
3 When specified, an assembly balance shall be performed, and the components shall be match marked. The coupling shall then be match marked and two-place balanced, with corrections being made only to the component or subassembly that was not periously balanced. The final residual unbalance of the assembled coupling in each of the two correction planes shall not exceed the greatest value determined by the following expressions:
U = 4W/N
U = 0.0008W
U = 0.01
In SI Units,
U = 6350W/N
U = 50.8W
U = 7.2
Where:
U = Residual unbalance, in ounce-inches
(gram Millimeters)
W = Weight of the component, in pounds (kilograms),
apportioned to the balance planes so that the sum
of the weight apportionment for both planes equals
the total weight of the component.
N = Maximum continuous operating speed,
In revolutions per minute.
4 When specified, the coupling shall be checked after the assembly balance to ensure that the assembly balance can be repeated. The coupling shall be disaaembled to the same extent required for normal field disaaembly and remounted on the balance fixture or fixtures. The unbalance of thr reasseambled coupling shall then be measured on the balancing machine, and the residual unbalance shall not exceed the greatest value determined by the following expressions.
U = 40W/N
U = 0.008W
U = 0.1
In SI Units,
U = 63,500W/N
U = 0.8W
U = 72.0
Note: Assembly balancing corrects for overall coupling unbalance caused by eccentricities of the pilot fits that are used to center components during assembly. However, assembly balancing may prohibited subsequent interchange of duplicate coupling components and may require that the entire coupling be maintained as a unit, except for the bolts and nuts.
U = 4W/N
U = 0.0008W
U = 0.01
In SI Units,
U = 6350W/N
U = 50.8W
U = 7.2
Where:
U = Residual unbalance, in ounce-inches
(gram Millimeters)
W = Weight of the component, in pounds (kilograms),
apportioned to the balance planes so that the sum
of the weight apportionment for both planes equals
the total weight of the component.
N = Maximum continuous operating speed,
In revolutions per minute.
1 When specifiedm residual unbalance checks shall be performed on components of couplings with maximum continuous speeds of 5000 revolutions per minute or greater. These residual unbalance checks shall be performed after balancing is complete and before the component is removed from the balancing machine.
2 Unless otherwise specified, couplings balanced in accordance with the above shall be assembled and the balance verified. The residual unbalance for the randomly assembled coupling shall not exceed the greatest value determined by the followin expressions:
U = 40W/N
U = 0.008W
U = 0.1
In SI Units,
U = 63,500W/N
U = 0.8W
U = 72.0
Where:
U = Residual unbalance, in ounce-inches
(gram Millimeters)
W = Weight of the coupling, in pounds (kilograms),
apportioned to the balance planes at the two coupling
hubs so that the sum of the weight apportionment
equals the total weight of the coupling.
N = Maximum continuous operating speed,
In revolutions per minute.
Couplings that fail to meet these criteria shall be balance corrected by repeating the component balance, not by trim balancing the assembly.
Sample plot and calculation of Resiudal Unbalance
3 When specified, an assembly balance shall be performed, and the components shall be match marked. The coupling shall then be match marked and two-place balanced, with corrections being made only to the component or subassembly that was not periously balanced. The final residual unbalance of the assembled coupling in each of the two correction planes shall not exceed the greatest value determined by the following expressions:
U = 4W/N
U = 0.0008W
U = 0.01
In SI Units,
U = 6350W/N
U = 50.8W
U = 7.2
Where:
U = Residual unbalance, in ounce-inches
(gram Millimeters)
W = Weight of the component, in pounds (kilograms),
apportioned to the balance planes so that the sum
of the weight apportionment for both planes equals
the total weight of the component.
N = Maximum continuous operating speed,
In revolutions per minute.
4 When specified, the coupling shall be checked after the assembly balance to ensure that the assembly balance can be repeated. The coupling shall be disaaembled to the same extent required for normal field disaaembly and remounted on the balance fixture or fixtures. The unbalance of thr reasseambled coupling shall then be measured on the balancing machine, and the residual unbalance shall not exceed the greatest value determined by the following expressions.
U = 40W/N
U = 0.008W
U = 0.1
In SI Units,
U = 63,500W/N
U = 0.8W
U = 72.0
Note: Assembly balancing corrects for overall coupling unbalance caused by eccentricities of the pilot fits that are used to center components during assembly. However, assembly balancing may prohibited subsequent interchange of duplicate coupling components and may require that the entire coupling be maintained as a unit, except for the bolts and nuts.
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