Abstract: A hub assembly for an articulated rotor system mounted on a rotor shaft comprises three plates centrally secured to the rotor shaft. The plates include generally radially disposed and axially spaced apart upper and lower plates and a cone shaped pan plate. The upper plate and pan plate have outer marginal portions transversely connected in adjacent relation and central portions connected to the rotor shaft in axially spaced apart relation. The upper plate and pan plate cooperate with the rotor shaft to form a truss for supporting blade retention assemblies equally spaced about the rotor shaft axis and mounted intermediate the upper and lower plates. One of the plates has a scalloped central aperture which cooperates with the scalloped mounting flange on the rotor shaft to facilitate angular orientation for bolt alignment during hub assembly installation.

Abstract: A neck for a stringed musical instrument has a metallic frame running substantially the entire length of the neck to provide a fingerboard and also to provide support for a peghead at the outer or upper end of the neck. The peghead portion of the frame cooperates with a mounting plate which may be varied in shape to suit different peghead styles and arrangements of the machine heads attached to the peghead, thereby allowing identical frames to be used in making necks with various different peghead designs. In addition to the frame, a major portion of the neck is comprised of structural foamed plastic with the construction being such as to enable quantity manufacture of the necks at low unit cost.

Abstract: A resonator constructed with mass and spring members is connected to a structure at a remote point n to produce an antiresonance at a different point p when the structure is subjected to an external vibratory disturbing force at a known frequency. The antiresonance is produced by tuning the resonator in accordance with parameters measured on the structure without the resonator.

Abstract: A method and apparatus for analyzing a damped structural specimen permits undamped mobility values and modal accelerations to be determined. The specimen is excited by vibrations in conventional fashion, and both actual and modified mobility response curves or characteristics are determined from measured responses. The modified mobility curve is produced by adding to a signal representing the vibratory force applied to the specimen an artificial force signal generated electronically. The generated artificial force signal simulates the addition or subtraction of mass at the point on the specimen where responses are measured. An undamped mobility value of the damped specimen is determinable at resonant frequencies indicated by the modified mobility curve. From the undamped mobility value and the corresponding frequencies, it is possible to determine modal accelerations for the various vibratory modes of the specimen.

Abstract: A method and apparatus for testing stress on a bolt head or nut having a central portion which deflects along the bolt axis as a function of stress, in which three electrical contacts, for example screws, are mounted in a line on and extending outwardly from a housing member, the two outer contacts being positioned to electrically connect to peripheral portions of a bolt head or nut when the center contact electrically connects to the deflected central portion and the head or nut has the desired pre-load. The outer contacts are connected to one polarity terminal of a battery via respective indicator bulbs while the center contact connects directly to the other polarity terminal so that both bulbs are lit when the contacts are so applied and the peripheral and central portions are in a given relation, preferably a single plane.

Abstract: An improved vibration isolator for reducing the transmission of vibrations between a supported body and a body suspended from the supporting body employs a pair of rotatable inertial masses that are coupled coaxially by an elastomeric spring. Suspension cables are wrapped around the rotatable masses and connect the masses with the supporting and the suspended body. The manner in which the cables wrap around the inertial masses causes the masses to roll back and forth along the cables when a vibratory load is applied to the cables from either one of the bodies. By appropriate tuning of the masses and elastomeric spring, the isolator can prevent the transmission of vibrations at a given frequency between the two bodies and thereby exhibits a zero impedance or transmissibility characteristic for isolating the bodies from one another insofar as the vibratory loads are concerned at the given or anti-resonant frequency.