Abstract: A fluid actuator characterized by a linear variable differential transformer (LVDT) feedback mechanism driven off the actuator screw shaft for indicating actuator position. A protective clutch mechanism prevents possible damage to the LVDT or actuator in the event that the actuator stroke exceeds the design stroke of the LVDT.

Abstract: Limited angle torque motor includes a rotor assembly having one or more permanent magnets which are magnetized in the diametrical direction and a stator assembly including a pair of circumferentially spaced stator magnetic pole pieces, each having a stator pole flange at the opposite end thereof. Each stator pole piece has a greater circumferential width in the region of the respective stator pole flanges to increase the amount of magnetic material in such region where the flux density is the highest. Surrounding the stator assembly is a magnetic housing which desirably effectively has no air gap therein.

Abstract: Landing gear mechanism includes a restrictor assembly containing a main orifice for controlling the rate of instroke of the landing gear mechanism during landing and a taxi instroke bypass valve which provides for increased flow of hydraulic fluid within the landing gear mechanism whenever the landing gear mechanism engages a bump during taxiing to reduce the damping loads that would otherwise occur if all of the hydraulic fluid were required to flow through the main orifice. The taxi instroke bypass valve assembly includes a slide member axially movable relative to the restrictor assembly for opening and closing one or more bypass orifices in the restrictor assembly. The slide member is held in the closed position whenever the landing gear mechanism is in a specified stroke range from fully extended by a secondary piston which is acted upon by the pressure in a precharged secondary chamber urging the secondary piston into engagement with a probe connected to the slide member.

Abstract: A fluid actuator characterized by a feedback mechanism for indicating actuator position. The feedback mechanism is driven by the actuator screw shaft, whereby the movements of the feedback mechanism are proportional to the rate and position of the actuator movements. The feedback mechanism and actuator movements may be synchronized so that the extreme end positions of the feedback mechanism will correspond to the fully retracted and extended positions of the actuator. A stroke limiting mechanism may also be provided for preventing the actuator from overstroking the feedback mechanism in the event that they are not properly synchronized.

Abstract: Dual tandem composite cylinder assembly includes a cylinder having circumferential or hoop stress windings surrounding a pair of hydraulic chambers in series to react the circumferential loads and prevent diametrical expansion of the hydraulic chambers. Longitudinal tension windings extend over substantially the entire length of the cylinder outwardly of the circumferential windings to react the axial loads which the cylinder must contain. Compressive cylinder composite windings are also provided for carrying compressive loads generated within the cylinder. The hydraulic chambers are desirably lined with removable liner members to facilitate changing of seals and refurbishment of the cylinder.

Abstract: Fluid actuator includes a composite cylinder having circumferential hoop stress windings wrapped about a liner member forming the piston chamber wall, and longitudinal tension windings extending from the outboard end of the cylinder along one side thereof and around the inboard end of the cylinder to the other side and back to the outboard end where they are secured to the cylinder. A compression column of composite material may be provided between a cylinder end wall and a permanent structure mount at the inboard end of the cylinder to extend the length of the cylinder to accommodate a tail stock on the piston of a pressure balanced actuator.

Abstract: A composite pressure vessel including a fluid port directly through the composite side wall structure formed by internally locating a porting fitting in the side wall structure and then inserting a liner member in the interior of the side wall structure. When thus assembled, a void space is provided between a flange portion on the radial inner end of the porting fitting and the liner member which is completely filled with a sealant. Then a porting hole is drilled through the sealant and liner member from the exterior fitting end. A nut may be threaded onto an exteriorly protruding end portion of the porting fitting and torqued to preload the porting fitting against the composite side wall structure. Also, composite material reinforcement may be applied locally around the protruding end portion (and nut).

Abstract: Ball drive mechanism includes a ball-like member on an eccentric output shaft of a rotary force motor which is received in a transversely extending cylindrical socket on a valve member. The outer diameter of the ball-like member is substantially the same as the inner diameter of the cylindrical socket to provide line contact therebetween at some distance radially offset from the longitudinal axis of the valve member which is at least as great as the eccentric offset, whereby the rotary output of the rotary force motor is translated into both linear and rotary movement of the valve member.

Abstract: Flow control valve includes angled metering ports in the valve sleeve for directing the momentum of the fluid flow against the respective valve flow metering edges in a direction producing an opening reaction force on the valve upon initial valve opening in opposition to the usual axial flow forces tending to close the valve to reduce the flow force gain acting on the valve. Preferably, the angled metering ports are disposed at an angle of approximately 45.degree. or greater from a line perpendicular to the valve axis. Also, a single set of circumferentially spaced angled metering ports is desirably provided for each return or high pressure flow path for producing the desired opening reaction force on the valve.

Abstract: A direct drive valve and force motor assembly including interchangeable stator assembly and method for accurately setting the magnetic spring null of the motor with respect to the servo valve hydraulic null independent of the actual motor stator assembly, whereby the motor stator assembly may be configured as an interchangeable plug-in module with interface electrical connector. This is accomplished by using a simple fixture which simulates the motor stator assembly and senses rotor magnet position. The stator simulating fixture may be used to rotatably adjust the position of the rotor casing so that the magnetic spring null corresponds to the hydraulic valve null. Both the stator simulating fixture and motor stator assembly include an index pin engageable with a stator alignment keyway in the rotor casing for maintaining the desired orientation therebetween. Also, rotor over-travel stops keyed to the rotor casing may be centered during the nulling process.

Abstract: Directional control valve includes a manually operated pilot valve stage and a hydraulically operated power valve stage to isolate the pilot valve stage from the effects of the high axial flows passing through the power valve stage. The pilot valve is spring loaded in the stow direction as long as the directional control valve is disconnected from system pressure. Such spring also acts as a stowed condition linkage pre-tensioner to avoid fretting of various parts during vibration conditions and the like. When system pressure is applied to the directional control valve, such preload is automatically removed from the pilot valve for ease of movement between the stow and deploy positions by a relatively low manual input rotary force.

Abstract: A lost-motion connection is provided between the armature core of a valve position sensor and the valve plunger preventing relative rotation therebetween while permitting relative axial movement by rotation of an adjuster sleeve having threaded engagement with extensions on both the armature core and valve plunger. Surrounding the adjuster sleeve is a locking collar having a multi-sided internal surface engaging a correspondingly shaped multi-sided exterior surface on the adjuster sleeve, whereby rotation of the locking collar causes rotation of the adjuster sleeve. The locking collar is also axially movable into and out of engagement with another correspondingly shaped multi-sided exterior surface on the valve plunger to respectively prevent and permit rotation of the locking collar relative to the valve plunger.

Abstract: A two-pole limited angle torque motor including a rotor assembly having one or more permanent rotor magnets and a stator assembly including a stator coil and a pair of circumferentially spaced stator pole structures. Each pole structure includes a generally axially extending stator pole blade about which the stator coil circumferentially extends. A radially outwardly extending flange is at one end of one of the stator pole structures and at the opposite end of the other stator pole structure. The stator pole blades have a greater radial thickness adjacent the flanges thereof than at the opposite end of the blade to reduce the magnetic flux density of the stator pole structures in the region of the blades adjacent the flanges thereof. Also, the axial outer end faces of the flanges desirably protrude axially outwardly adjacent the radial inner ends thereof to make use of the fringing fields of the rotor magnet at the ends of the rotor assembly to increase the reluctance torque of the motor.

Abstract: Limited angle torque motor includes a rotor assembly having one or more permanent magnets which are magnetized in the diametrical direction and a stator assembly having a plurality of axially spaced pairs of stator pole pieces, each pair having a stator coil extending circumferentially therearound. Each stator pole piece includes a generally axially extending pole blade and a radially outwardly extending flange portion at one end only of each pole piece, said flange portions being at opposite ends of the pole pieces of each pair. One or more of the stator coils and associated pairs of pole pieces may be rotationally offset with respect to one or more other coils and associated pairs of pole pieces to provide for the reshaping or widening of the resulting magnetic reluctance and interaction of magnetic fields torques versus rotation characteristics for a given motor design.

Abstract: Limited angle torque motor includes a motor power section comprising a rotor assembly having one or more permanent rotor magnets which are magnetized in a diametrical direction and a stator assembly surrounding the rotor assembly. The magnetic flux in the motor power section produces an inherent magnetic centering spring rate tending to keep the rotor assembly at the midpoint of its rotational angle range. However, when a direct or pulse width modulated current is applied to the stator windings, a cross flux is produced through the stator and rotor assemblies of the motor power section which produces the desired limited rotational angle range for the rotor assembly. The motor also includes a separate magnetic centering spring section which provides another centering spring function in addition to the basic centering spring function inherent in the motor power section.

Abstract: Landing gear mechanism includes a restrictor assembly containing a primary orifice for controlling the rate of instroke of the gear during landing and a taxi instroke bypass valve which provides for increased flow of hydraulic fluid within the gear whenever the gear engages a bump during taxiing to reduce the damping loads that would otherwise occur if all of the hydraulic fluid were required to flow through the primary orifice. The taxi instroke bypass valve assembly includes a bypass passage around the primary orifice, and a slide member which is axially movable relative to the orifice restrictor assembly for opening and closing the bypass passage.

Abstract: Spherical ball drive mechanism for directly coupling a rotary force motor to a valve member, includes a spherical bearing assembly at one end of the valve member. The spherical bearing assembly consists of an outer race member having a concave spherical inner bearing surface and a spherical bearing member having a convex spherical outer bearing surface complementary to the concave spherical inner bearing surface of the outer race member and received therein. The outer race member has a longitudinal axis substantially perpendicular to the longitudinal axis of the valve member and a transverse center axis radially offset from the longitudinal axis of the valve member. An eccentric output shaft of the rotary force motor extends substantially perpendicular to the longitudinal axis of the valve member for receipt in a longitudinal bore in the spherical bearing member.

Abstract: A fluid servo actuator control/damping mechanism and method which utilize and combine the functions of an electro-mechanically driven servo valve to achieve ram or actuator fluid flow and load control even after loss of fluid power as well as the main ram position control function under normal operating conditions.

Abstract: Landing gear mechanism includes a built-in hydraulic actuator which may be actuated to provide a heavy load range, soft spring rate during take-off with a heavy take-off weight and a lower load range, softer spring rate after take-off and prior to landing with a lighter landing weight to yield more shock strut stroke for a given range of vertical load during landing. A special taxi valve allows for some fluid to bypass the main orifice more freely to and from the lower piston damping chamber to the shock strut air-oil chamber as soon as the landing energy stroke is complete to greatly reduce or eliminate high damping loads that might otherwise take place as the gear negotiates bumps. Such a valve may automatically be set to close for landing by the action of the gear extension during a subsquent take-off, thus reactivating the main orifice.

Abstract: An electro-mechanical direct drive valve servo system for an aircraft including a drive mechanism that couples the rotary output motion of a rotary force motor to linear motion at a sliding-type valve. The drive mechanism includes a pair of axially spaced rotary members connected to the force motor and a wobble member journaled between and canted by the rotary members with axial thrust bearings interposed between axially aligned opposed planar faces of the rotary and wobble members. A radial output arm on the wobble member is connected to the valve and is constrained for arcuate nutating movement whereby controlled rotation of the rotary member effects nutating movement of the wobble member and output arm which movement effects controlled linear movement of the valve. Additional control inputs such as braking and recentering function inputs are accommodated by the drive mechanism at its input end to take advantage of the mechanism's inherent gearing force ratio.