Abstract: A helicopter mast is driven by a transmission with a swashplate individually linked to pitch horns on each rotor blade. At least four actuators are coupled to the swashplate, three of which normally control the attitude and position of the swashplate. A separate power unit is provided for each actuator, each power unit being independently driven from the transmission. Means are then provided to shift control of the swashplate from one of the three actuators to a fourth actuator upon any one becoming disabled.

Abstract: Gapping of slide fastener tapes is performed by cutting longitudinal connecting and supporting members carrying fastening elements on both sides of each element to be removed along perpendicular cutting lines. The fastening elements are then removed by pulling the fastening elements and the severed ends of the connecting and supporting members from between loops of weft threads which secure the connecting and supporting members in the inner edges of the tapes.

Abstract: A helicopter having a main rotor lift unit includes a plurality of pendulus mass units (44, 46) mounted to oscillate in a plane perpendicular to the chord plane of the rotor blade (10). The mass units (44, 46) are connected to a rotatable shaft (28) which passes through or adjacent the blade grip (12) for each blade (10). Hubshear vibrations generated parallel to the axis of the rotor mast (18) are damped by the oscillating mass units (44, 46) which are tuned to minimize the vibrations transmitted from the lift unit to the fuselage.

Abstract: A helicopter having a multiblade main rotor lift unit includes a plurality of pendulus mass units (48,60) mounted to oscillate in the plane of the rotor. The mass units (48,60) are connected to a rotatable shaft (24) which passes through a blade grip (14) for each blade (16). Vibrations generated in the plane of the rotor system are damped by the oscillating pendulums (22) which are tuned to minimize the vibrations in the lift unit.

Abstract: A three-part seal to be fixed in a gland formed on the first of two mating cylindrical structures in a hydraulic apparatus. A continuous Teflon nondeformable bearing ring is provided in the gland. The bearing ring has a first cylindrical surface for contact with the second cylindrical structure, a second cylindrical surface opposite the first surface and a conical rearward facing end surface. A continuous Teflon nondeformable backup seal ring is provided in the gland for mating with the rearward facing conical end surface of the bearing ring against its forward facing conical end surface. A continuous compressible resilient ring is provided on the side of the bearing ring opposite the second cylindrical structure for contacting the bearing ring and the backup seal ring.

Abstract: A slide fastener installation is disclosed for use in a sleeping bag, jacket or other article. The slide fastener installation is formed from one continuous slide fastener stringer and one end of the installation is formed by that stringer being looped back on itself. A separating end stop is formed at the other end of the installation and includes a separating end device formed by removing the head portion from a series of coupling elements.

Abstract: Separating slide fastener tapes are installed on opposite article portions by first sewing one of the article portions to one half of a single slide fastener stringer tape section, and then sewing the other article portion to the other half of the single slide fastener tape section which has a retainer at one end and a pin member at the other end. The single slide fastener stringer tape section is severed between the sewn article portions and the article portions are finished to secure the severed ends of the single slide fastener tape section. A slider may be installed on the retainer half of the slide fastener stringer tape section at any time during the manufacture of the slide fastener stringer tape section or the attachment of the article portions prior to the finishing of the article portions.

Abstract: A coupling element, such as a scoop formed from a synthetic polymer, for a slide fastener includes a head with a triangular side cross section bounded by a top surface and two downwardly converging bottom surfaces which extend at equal angles relative to legs of the coupling element. Leg sections adjacent the head are disclosed as being formed with oriented polymer for increased strength.

Abstract: A display heading for notions is particularly designed for use with a perforated board support that is utilized to merchandise a plurality of notions in sets of common series or groups. The notions display heading is made of plastic with rear-surface fasteners having hook like elements that project through selected apertures in the perforated board support.

Abstract: A positioning member is moved transverse to a slide fastener chain after advancement of the slide fastener chain to a gapping and stop applying station to position fastening elements of the slide fastener chain in a channel extending in the station. The slide fastener chain is clamped and gapped, and a bottom stop is applied to the chain.

Abstract: A vibration isolator (10) includes an outer housing (14) with an inner housing (16) supported for reciprocation therein. The inner housing (16) includes an elastomeric spring (32) supporting a sleeve or inner cylinder (30) with a passage (44) extending therethrough interconnecting a pair of spaced apart chambers (40,42) defined between the housings (14, 16). A tuning mass including liquid is disposed in the chambers (40,42) and the passage (44). The inner housing (16) functions as a piston to move the tuning mass through the inner cylinder (30) between the chambers (40,42) and generate amplified counter-inertial forces to cancel vibration.

Abstract: A pressure switch unit capable of withstanding high pressures without losing its low pressure sensitivity or calibration includes a magnetically actuated switch responsive to the magnetic field of a permanent magnet mounted on a hermetically sealed bellows which contains on its interior a substantially incompressible liquid. The amount of liquid hermetically sealed within the bellows is selected to be sufficient to prevent any portion of the bellows from exceeding its elastic limit when the bellows is compressed by exposure to excessively high pressures.

Abstract: A supersonic diffuser for diffusing a low pressure radially expanding supersonic flow to a subsonic flow of increased pressure. In applications having cylindrical geometrics, the diffuser includes a plurality of radially extending, angularly spaced vanes having blunt leading edges which function to generate a detached upstream bow shock.

Abstract: A process is described for the preparation of urethane prepolymers from hydroxy-terminated diene polymers and normally liquid, relatively non-volatile, aromatic polyisocyanates. The prepolymers are made at a temperature above about 150.degree. C. to provide urethane prepolymer products that resist the tendency to form multiple phases or layers upon storage at room temperature.

Abstract: A binder seal or reinforcing and finishing strip for the end of a slide fastener is formed by bonding superimposed layers consisting of nylon 6 and a blend of nylon 6 and nylon 6-6 wherein the blend forms an inner layer and the bonding temperature is selected at the melting point of the inner layer but substantially lower than the melting point of the outer film.

Abstract: Low-cost articles characterized by a surface of revolution, such as truncated spherical balls, e.g., plain spherical bearing balls, are provided made by the powder metal compaction and sintering of blanks followed, in the case of ball elements, by densification of the outer spherical surface by mechanical working, such as by roll-forming, the balls so produced being characterized by improved sphericity and dimensional tolerance and improved wear resistance combined with optimum resistance to corrosion. The spherical surface of the ball is substantially free of pores, has a work hardened structure and has a density at and adjacent the surface of at least about 95% of the theoretical density of the metal, the density substantially below the surface being less and ranging to as low as at least about 70% of theoretical density.

Abstract: A valve for controlling fluid flow in a fluid system such as a pipeline which includes a body defining an internal chamber in fluid connection with an inlet and an outlet. The valve further includes a deformable valve liner mounted within the chamber which sits against a valve seat and a frustoconical grill having a plurality of ports therein. The liner and the body define a control chamber which is coupled to a source of controlled pressure. A relief region is provided between the liner and the grill at the plane of intersection of the liner and the grill.

Abstract: A failure detection apparatus useful with a hydraulic system for maintaining fluid pressure signals present in the system to detect predetermined disparity therebetween. The apparatus includes a movable sleeve mounted within a housing and defining a central bore as well as transverse fluid flow passageways therethrough. A piston is mounted within the bore in the sleeve and normally blocks the fluid flow passageways defined within the sleeve. Fluid pressure signals to be monitored for detection of disparity therbetween are applied to opposite ends of the movable sleeve. Upon movement of the sleeve, fluid under pressure is applied through the passageways and through bores provided in the pistons thereby to cause movement of the piston to apply the fluid under pressure to a shut-off valve and a failure indicator mechanism. The piston latches in a limit position to retain the detection device and the shut-off valve in the actuated position.

Abstract: A parallel actuator pair force transmission system including a mechanical feedback apparatus capable of detecting differential movement between the actuator pair and providing a feedback signal to control valves phased in such a manner as to correct for and counteract the differential motion between the actuator pair.

Abstract: A slide fastener is disclosed including mounting tapes each having a warpless area or a void area formed in them near their adjacent edges. Coupling elements are secured onto the edges of the mounting tapes and plugs of material interconnecting the legs of each coupling element extend through the void area or warpless area of the mounting tapes. Interconnecting straps are also formed in the warpless areas linking each adjacent pair of the coupling elements.