Goodrich Rome

104 Otis Street
Rome, NY 13441-4714
Phone: 315-838-1200
Fax: 315-838-1477

Commercial Couplings Retrofit Applications and Balance Standards

Retrofit Applications

Goodrich Diaphragm Couplings are used frequently to replace gear, disc and other dry type couplings. Contact Goodrich with your retrofit requirements.

Balance Standards

Goodrich has standardized on a method of balance which eliminates the errors associated with arbor balancing:

Hubs are component balanced on a vertical machine with bores indicated concentric to the rotating table. They are balanced in two planes. Balance journals are ground on the OD of hubs concentric to the hub bore.
The coupling is assembled with a prebalanced adapter installed within the hub bores. Concentricity of this adapter is maintained using spreader screws. Adjustment screws are used to stretch the diaphragms and rigidize the assembly.
Alignment involves rotating the coupling on its balance journals and indicating bore diameters. By adjusting adapter screws, hub bores are aligned to within 0.0002 T.I.R. Data recorded during alignment is used to compute the eccentricity which exists between the centerline of balance journals and the actual centerline of the hub bore. This eccentricity is corrected for during the balance operation.

Degree of Balance

The accompanying formula is used to calculate the balance tolerance per plane for any given coupling. The value of K assigned is usually dependent upon coupling application. The lower the value of K the tighter the balance tolerance.

U = KW

U = Residual Unbalance per Plane

(--In-Oz)

W = Plane Weight (--Lb)

N = Max Continuous Operating Speed

(--RPM)

K = Constant Denoting Degree of Balance

Balance Repeatability

The coupling assembly, with its fixtures, is balanced so that the unbalance (expressed as the distance between the coupling’s center of gravity and its center of rotation) is very small, generally less than 0.000050 inches.

However, even with the best of care small errors in the relative location of mating parts occur when the coupling is disassembled and then reassembled. These errors often add up to about 0.000400 inch on our couplings. Thus, when a balanced coupling is checked for repeatability, unbalance values equivalent to U In-Oz = 0.0064 x W lbs can be expected.

To minimize these reassemble errors the Goodrich couplings:

Are lightweight.
Have a minimum number of assembly joints.
Are matchmarked for consistent assembly.
Have all machining done before balancing.
Have no surfaces which wear.
Are dimensionally stable.
Have weight-matched bolts and nuts.
Have zero clearance diametral locating pilots (Models 88 & 100).
Have close-fitting locating bolts (Models 68, 87 & 99).

E-mail: info.rome@goodrich.com

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