HPLogoArt.gif (2650 bytes)          Propeller Balance

Geometric Balance:

Also referred to as "Blade Matching", this process is the analysis of the configuration of each blade in comparison to each of the other blades. In order to be considered in correct geometric balance each measured position on the blade should be the same as the identical point on each of the other blades (within tolerance). Due to the number of analysis points available and the fact that the propeller is electronically measured in three dimensions the Hale MRI is the ideal method of matching propeller blade geometry. Our measuring method records the actual blade pressure surface offsets therefore allowing contour to be measured and displayed.

Mechanical Balance:

An important requirement of all rotating machinery is that the rotation axis coincides with one of the principal axes of inertia of the body. After a wheel has been manufactured, modified or repaired, it must be balanced to satisfy this requirement, especially for higher speed vessels. The condition of unbalance of any rotating body may be classified as static or dynamic unbalance.
Static Balance is the mechanical balance of the propeller in the plane of rotation. This can be measured by inserting a special arbor into the bore and placing this assembly onto a stand wherein the rotation of the propeller is in the vertical plane
and the arbor rests upon bearings. Because the propeller is allowed to freely rotate the heavier blade(s) will rotate to the downward most position. Weight is either added or removed until the propeller will remain static in any rotational position.
A propeller may be in perfect static balance and still not be in a balanced state when rotating at high speeds.
Dynamic unbalance is a "couple" or a "twisting" force in two separate planes. Because these forces are in separate planes, they cause a rocking motion fore and aft -or- side to side. A perfectly good propeller (geometrically) that is unbalanced will cause mechanical vibrations and a decrease in bearing life and efficiency due to unnecessary forces. The only scientific manner in which
to accurately measure and therefore correct dynamic unbalance is through the use of a true multi-plane dynamic balance analyzer.
At Hale Propeller we offer the customer the option of having their propellers dynamically balanced using the
Dynamics Research 602 Multi-Plane Computerized Dynamic Balance System.

DynamicBalDave.gif (186204 bytes)38" Diameter 5 Blade being Dynamically Balanced

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