The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 12, 1985
Filed:
May. 31, 1983
Louis C Hrusch, Chesterland, OH (US);
Pneumo Corporation, Boston, MA (US);
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. 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.