Pneumo Corporation

Pneumo Abex Corporation

Louis C Hrusch

Richard A Blincoe

Richard J Winn

Landing gear mechanism includes a variable area orifice to obtain the desired rebound damping of the landing gear mechanism during landing, and one or more check valve assemblies that operate in conjunction with the variable area orifice to provide the desired controlled instroke of the landing gear mechanism during landing. Also, the landing gear mechanism is provided with a relief valve assembly that permits bypass flow at a pre-set pressure drop only during an intermediate portion of the instroke of the landing gear mechanism to attenuate severe bumps and the like without adversely affecting the controlled instroke and rebound damping of the landing gear mechanism during landing.

Landing gear mechanism including controlled instroke and rebound damping

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. At some point in the strut stroke, the pressure within the upper piston chamber of the landing gear mechanism will rise to that of the precharged secondary chamber, whereby the secondary piston will be stroked along with the main strut piston and the slide member will move to the open position allowing fluid to bypass the main orifice, thereby reducing the damping loads as the landing gear mechanism negotiates bumps during taxiing.

Landing gear mechanism including bypass valve assembly for reducing

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.

Landing gear mechanism including runway-roughness restrictor assembly

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. For normal bounce, air in the primary chamber drives oil through an orifice in a rebound damper valve to the lower piston chamber in order to lift the supported weight of the aircraft as part of the return stroke. However, when riding over a hole, the air acts freely on the differential or net piston area of the gear which area is too small to lift the supported weight of the aircraft, but is large enough to accelerate the unsprung mass of the gear quickly into the hole. An anti-cavitation bypass valve assures oil refill in the lower portion of the piston chamber as the gear extends. Also, a pressure actuated valve may be provided in the metering pin which, upon sensing cavitation in the lower piston chamber during extension, will open a series of holes both above and below the main orifice, providing a flow path for oil around the main orifice, to eliminate the aforementioned cavitation. The metering pin is part of this flow path. A check valve may be provided at the top of the metering pin to keep the metering pin full of oil by allowing free flow of oil upward but not allowing downward flow, thus preventing the intake and down flow of shock strut air during the anti-cavitation re-fill of the lower piston chamber. An extension snubber valve may also be provided to develop piston rebound damping during the last portion of stroke of the landing gear before full extension thereof during take-off.

Landing gear mechanism for use on rough runways

Servoactuator includes a pair of double-acting linear actuators providing for 360.degree. controlled rotation of an output shaft. The rotary motion of the ouput shaft is employed to sequence high pressure fluid flow and return for the same to the respective ends of the respective actuators so that both actuators continuously develop output force except for end stroke points. Shimmy damping may also be obtained by a bypass-damping valve which comprises a shuttle movable to a first position by high pressure fluid for controlled operation of the servoactuator and to a second position by removal of the high pressure fluid to direct fluid flow between the respective actuators through a damping orifice.

Dual cylinder linear servo motor

A radially expandable and contractable split lock ring selectively to unlock and lock a piston and cylinder actuator includes at least one lapped axially extending surface substantially conforming to the surface of the cylinder or piston with which it is in sliding contact when in the unlocked position. The split lock ring has each of its ends slightly inwardly tapered to reduce the thickness thereof to distribute the bending load uniformly throughout the ring and has a flat on the outer diametrical surface diametrically opposed from such tapered ends to provide load carrying symmetry for the ring.

Split lock ring for locking actuator and method for manufacturing the

An articulated, retractible landing gear for helicopters and the like includes a three member drag brace assembly having a retraction brace pivotally connected to the helicopter fuselage at its inboard end and to an upper drag brace at its outboard end, with the latter pivotal connection being along the articulation axis of the landing gear, the upper brace being pivotally connected at its other end to a lower brace which in turn is connected to the oleo strut of the landing gear by a universal joint, the pivotal connection between the upper and lower braces in the extended position of the landing gear being on an axis normal to both the drag brace center line and the articulation axis.

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Chesterland, OH, United States of America

Louis C Hrusch