Technical Documentation
Balance of a blower
An unbalanced rotor (fan runner in the case of an air conditioner) not only exerts alternating forces on the bearings and foundations, but also causes mechanical vibration. To accurately determine the balance of a rotating machine, experiments on vibration and noise, etc., must be carried out on-site or in a laboratory according to the conditions of use to determine the balance, or the balance must be calculated so that the unbalanced forces acting on the bearings do not reach the bearings’ tolerance limits.
Recommended balance of various rotating machines
The table below shows the recommended balance grades obtained from past experience for representative rotating equipment (rigid rotors) of different types, sizes, and rotational speeds.
Recommended balance grades
| Balance quality grade Upper limit of balance quality mm/s (eper×ω) (1)・(2) Rotor type example | ||
|---|---|---|
| G4000 | 4000 | Crankshaft system of a rigidly supported low-speed marine diesel engine (3) with an odd number of cylinders (4) |
| G1600 | 1600 | Rigidly supported crankshaft system of a large two-stroke engine (4) |
| G630 | 630 | Rigidly supported crankshaft system of a large four-stroke engine (4) |
| Elastically supported crankshaft system of a marine diesel engine (3) (4) | ||
| G250 | 250 | Rigidly supported crankshaft system of a high-speed four-cylinder diesel engine (3) (4) |
| G100 | 100 | Crankshaft system of a high-speed diesel engine (3) with 6 or more cylinders Finished engines (gasoline or diesel) for automobiles, trucks, and railway vehicles (5) |
| G40 | 40 | Wheels, rims, wheel sets and drive shafts for automobiles |
| Crankshaft systems (4) of high-speed four-stroke engines (gasoline or diesel) with six or more cylinders on elastic supports (3) | ||
| Crankshaft systems (4) of engines for automobiles, trucks and railway vehicles | ||
| G16 | 16 | Driveshafts with special requirements (propeller shafts, cardan shafts) |
| Parts for crushers | ||
| Parts for agricultural machinery | ||
| Parts for engines (gasoline, diesel) for automobiles, trucks and railway vehicles | ||
| Crankshaft systems (4) of six or more cylinders with special requirements | ||
| G6.3 | 6.3 |
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| Small armatures (mainly mass-produced) for use in vibration-insensitive applications or with vibration insulation | ||
| Engine parts with special requirements | ||
| G2.5 | 2.5 | Gas turbines, steam turbines and marine main engine turbines (for merchant ships) |
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| Small armatures (excluding those in the conditions of G6.3 and G1) | ||
| Small armatures for turbine-driven pumps | ||
| Engine parts with special requirements | ||
| G1 | 1 |
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| Small armatures with special requirements | ||
| G0.4 | 0.4 |
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〈Table Notes〉
Valance
