EFFECT OF VERTICAL HEIGHT SETTING ON SENSITIVITY OF UNBALANCE INDICATION

TM 55-4920-201-14

unbalance force, introduced by addition of weight

unbalance is present in the assembly being checked.

w at distance d, is the same in all four views and

(See figure 7-2). Once this setting has been

represents the maximum permissible unbalance for

established, subsequent similar assemblies, using

the assembly. In view A, with the disc mounted at

the same setting, are directly indicated as "inside"

the lower end of the arbor, balance sensitivity is too

or "outside" balance tolerance limits by the relative

low to provide a visible indication of the small

position of the indicator circles. This feature

unbalance force. In view B, mounting the disc

eliminates the need for any calculations by the

higher on the arbor increases sensitivity so that a

operator; when the indicator bushing circle is

visible indication of the small unbalance force is

anywhere inside the black indicator disc circle, the

observed. By mounting the disc still higher on the

indicated unbalance is smaller than the balance

arbor, sensitivity is further increased until the

tolerance limit.

indicator bushing circle becomes tangent with the

7.14. EFFECT OF VERTICAL HEIGHT

indicator disc circle, as in view C. This is correct

SETTING ON SENSITIVITY OF UNBALANCE

sensitivity for the assembly (balance tolerance = w x

INDICATION. (See figure 7-2).

d). In view D, mounting the disc still higher on the

7-15. The bare disc in all four views of figure 7-2

arbor results in an excessive degree of sensitivity, or

represents the same balanced mass. The small

actual instability.

7-3