Abstract: The invention relates to a safety device for a system transported on board a vehicle, in particular an aircraft, said system being connected to the structure of the vehicle via at least one element having a cylindrical body and a telescopic rod. According to the invention, the body and the rod of each element together define two internal fluid chambers which are normally isolated from each other, a communication passage being provided between the two chambers and normally being closed by an associated throttling valve, the throttling valve being controlled by acceleration-sensing means using a mass that is movable in the axial direction of the telescopic element and that is associated with a rated spring. The means is organized to cause the throttling valve to open as soon as the sensed acceleration exceeds a threshold which is predetermined as a function of the system to be protected, the acceleration of the system thus being kept below the threshold by the telescopic element changing in length.

Abstract: The invention relates to aircraft landing gear of the type that is laterally-raisable and that has twin wheels in a side-by-side configuration. According to the invention, the leg is constituted by an upside-down L-shaped strut whose two branches are hinged together, comprising a beam-forming first branch that is hinged to the structure of the aircraft and a second branch having a wheel lever hinged to the end thereof. The wheel lever is also connected to the first branch via a shock absorber. A controlling guide bar connects the second branch to the structure of the aircraft via a fork swivel-mounted on said second branch, in such a manner as to cause said second branch to move forwards while the landing ger is being raised, such forwards movement causing the wheels to be folded in because the shock absorber then acts as a second guide bar.

Abstract: The invention relates to a raisable undercarriage comprising a hinged leg and associated bracing means. According to the invention, the undercarriage is of the leg-shortening type, and the bracing means are organized in the form of a foldable brace having its bottom arm hinged to bottom end of the sliding rod of the hinged leg, said brace further being organized so that, in the undercarriage down position, the lowered leg slopes towards the front of the aircraft.

Abstract: The invention relates to controlling an electrohydraulic braking apparatus of a wheel set in which each wheel is fitted with a brake that is actuated from brake pedals by way of a servo-valve that is electrically controlled by a control unit which measures information relating to the degree of depression of the pedals. According to the invention, when an aircraft is taxiing, braking for the wheels in a first group is organized separately from braking for the wheels in a second group, applied braking pressure varying as a function of brake pedal depression in compliance with respective relationships specific to each of the groups of wheels, which relationships operate over the entire active range of brake pedal depression.

Abstract: The invention relates to an electro-hydraulic braking system for the wheels of aircraft landing gear. The system comprises two hydraulic pressure sources each feeding a hydraulic circuit that leads to the brakes of two groups of wheels via a single braking control stage. A circuit connects either a solenoid valve electrically controlled by the control unit or else a double metering valve mechanically controlled by the brake pedals via two shuttle valves, to one inlet of each control stage. A second circuit directly connects a solenoid valve to a second inlet of each of said control stages. Each control stage includes two symmetrical internal circuits having one servo-valve per corresponding brake, which servo-valves are cross-connected by means of a respective corresponding controlled valve. In the event of one of the circuits breaking down, the servo-valves associated with the other circuit then serve, after automatic reconfiguration, also to provide braking and anti-skid control in a paired tandem mode.

Abstract: The strut of the leg has a lateral extension on its outside above the rotary sleeve, the cylinder of a steering actuator is suspended from the lateral extension by means of a universal joint, the end of the rod off said actuator is hinged to a lateral steering lug of the rotary sleeve. This flexible disposition puts fewer constraints on implementation of the scissor linkage, and it improves guidance of the rotary sleeve.

Abstract: A linear actuator, in particular for driving an aircraft landing gear leg, the actuator comprising a main body with a screw that is prevented from moving axially and that is constrained to rotate with a coaxial gear wheel that meshes with the outlet gear wheel of a driving motor and gear box assembly, and a nut that is secured to a sliding guide rod inside said main body. According to the invention, the rotary connection between the screw and the coaxial gear wheel is provided by declutchable coupling means, which means is declutched in an emergency for the purpose of releasing the screw by associated trigger means whose operation requires very little energy.

Abstract: The running gear comprises a tilting beam having one end hinged to the vehicle about a tilt pin and supporting a rotary axle for at least one wheel, a blade spring having a first end fixed to the vehicle and a second end hinged to a first end of a shock absorber having a second end hinged to the vehicle, and a control actuator hinged firstly to the second end of the blade spring and secondly to a tilting control pin carried by the tilting beam at a point that is spaced apart from the tilting pin in order to control the tilt of the tilting beam.

Abstract: A locking device including a box, a primary latch made in the form of a tilting hook, and a retractable locking member. The locking device further includes a secondary latch made in the form of a sliding member. The sliding member is displaceable between a retracted, open position and an extended, closed position in which the sliding member is in the direct vicinity of an associated catch member. The locking device is particularly applicable to locking the thrust-reversing flaps of aircraft jets.

Abstract: The invention relates to raisable landing gear including a shock absorbing leg that is pivotally mounted, and to a driving actuator associated therewith. According to the invention, the leg is implemented in the form of two elements that are hinged to each other about an axis parallel to the pivot axis of the leg and that are connected together by means of a shock absorber, the bottom element forming a rocker and the top element forming a panel whose free end is connected to a drive actuator which is a shock-absorbing actuator having a force threshold, said shock-absorbing actuator serving to apply a predetermined torque that maintains the leg in position during normal landing, while allowing said leg to be raised against a controlled force in the event of a crash landing.

Abstract: The invention relates to a force-limiting device for aircraft landing gear shock absorbers, in particular for helicopters, and also to a shock absorber fitted with such a device. According to the invention, a box 201 is provided that forms a partition in the main body 101 of the shock absorber, the box having a bottom 202 whose central portion has a diaphragm 210 with small throttling orifices 211 and force-limiting members also being provided comprising firstly an annular valve member 225 disposed around the diaphragm 210 such that when open it allows a large volume of hydraulic fluid to pass through the box in a very short time, and a resilient return member 226 holding the annular valve member 225 in its closed position, but allowing the valve member to open above a predetermined threshold.

Abstract: The invention relates to a method of burnisning for the purpose of imparting surface compression stresses to metal parts. The surface state of the region of the part that is to be burnished is measured initially, and the width of the disk to be used in the burnishing is deduced therefrom. Thereafter, the disk selected in this way is installed on a tool carrier, at the end of an associated flexure bar. Once installed in this way the disk is pressed against the part to exert a predetermined force thereon as a function of the desired surface compression stresses. Finally, burnishing proper of the part is performed using the disk. The burnishing method of the invention is particularly advantageous for use with light alloy wheels, e.g. wheels made of magnesium or of aluminum alloy.

Abstract: The invention relates to an oscillating arm suspension assembly for a heavy vehicle, in particular for a track vehicle. According to the invention, the oscillating arm comprises a housing receiving firstly a shock absorber of the type in which a semi-solid elastomer is hydrostatically compressed, said shock absorber being mounted coaxially about the oscillation axis of said arm, and secondly an oleo-pneumatic spring of the two-chamber type, having a hydraulic chamber closed by a sliding piston with a piston rod hinged thereto whose end opposite from the piston is hinged to a fixed member inside said housing.

Abstract: The invention relates to a shock absorber for a landing gear leg, the shock absorber being of the type comprising a cylinder and a sliding rod, and including a disk that delimits a lower hydraulic fluid chamber which communicates via a diaphragm with an upper hydraulic fluid chamber adjacent to a pressurized gas chamber formed in the top portion of the cylinder. According to the invention, the sliding rod 102 is implemented in telescopic form, having an outer rod 131 and an inner rod 132 which bears directly against an intermediate partition 112 constituting the above-mentioned disk when the shock absorber is relaxed or under static load. The shock absorber also includes a linear actuator 150.1 received in the inner rod 132, and which, when triggered, serves to extend the landing gear providing the airplane is stationary or is moving slowly on the ground. Two scissors linkages 124 and 127 are also provided for conveying structural twisting forces.

Abstract: The invention relates to a shock absorber of the type comprising a cylinder and a sliding rod, together with a moving disk that defines a bottom hydraulic chamber that communicates via a diaphragm with a top hydraulic fluid chamber that is adjacent to a pressurized gas chamber formed in the top of the cylinder. According to the invention, a self-contained linear actuator is disposed coaxially inside the sliding rod, being interposed between the moving disk and a lower abutment secured to said sliding rod, independent control means being also provided to control the linear actuator, such that when said means are engaged they enable the landing gear to be extended when the aircraft is stationary on the ground.

Abstract: The invention relates to raisable landing gear having a shortenable leg, including a shock absorber fitted with a plunger rod, and a linkage connecting said plunger rod to the strut of the shock absorber, under the control of a resilient connecting rod having a threshold, serving to pull on the shock absorber when the leg is raised. According to the invention, the linkage includes two arms forming an alignment, with a first arm hinged on the plunger rod and having a lateral appendix whose free end is capable of co-operating with a stationary cam secured to the structure of the airplane, and a second arm which is hinged to the strut. The lateral appendix and the stationary cam are organized to operate in an emergency, in the event of the threshold connecting rod failing, thereby ensuring that the shock absorber is extended and that said lengthened shock absorber is locked in the undercarriage-down position.

Abstract: The invention relates to a shock-absorbing actuator including a cylindrical body and a hollow rod having an annular piston. The cylindrical body includes a separator piston delimiting two hydraulic fluid chambers, one of which communicates via a distributor valve with the hydraulic circuit of the aircraft, said distributor valve being closed automatically at the end of lowering the landing gear; the annular chamber communicates via a second distributor valve with said hydraulic circuit. The distributor valves thus make it possible to extend and retract the shock-absorbing actuator. In addition, a force peak-limiting means is disposed in an extension extending beyond an end wall of the body that forms one of the abutments for the separator piston.

Abstract: The invention relates to a catch device of the type comprising a main casing that houses a hinge hook and a locking lever having one branch carrying a thrust wheel that co-operates with the hook and having its other branch connected by means of a linkage to the outlet from a driving motor and gear box assembly. According to the invention, the linkage (112) includes an oblong slot (122) for enabling the locking lever (106) to pivot in the event of the outlet shaft (113) of the motor and gear box assembly being jammed, and, in addition, an independent trigger (130) is associated with the locking lever (106) so that when triggered in an emergency it causes said lever to pivot far enough to disengage thrust wheel (109) from the associated camming surface (110.1) of the hinged hook (102), thereby releasing it.

Abstract: The invention relates to a system for powering the driving actuator of an aircraft undercarriage, the system including a hydraulic generator capable of delivering fluid under pressure to one or the other of two chambers of the driving actuator. According to the invention, the power supply system includes a safety device enabling any overloading of the actuator rod under the effect of pressure peaks to be avoided: said device comprises two pressure relief valves, the first valve limiting the pressure delivered to the annular chamber and being under the control of the pressure in the full-section chamber, and the second pressure relief valve being of the differential type and continuously controlling the pressure difference between the two chambers of the actuator. The invention is applicable to providing very safe power supply systems for aircraft undercarriages.

Abstract: The invention relates to a shock absorber comprising a main body and a rod-piston, with the rod-piston being retracted when the landing gear is down and extended when the landing gear is up. The main body comprises, in succession, three chambers that are separated by associated partitions, and that comprise: a first hydraulic chamber in which the rod-piston slides freely; a chamber in which a separator piston slides, delimiting a second hydraulic chamber; and a chamber in which another piston slides, delimiting both a third hydraulic chamber and a chamber containing gas under high pressure. Communication means are provided between said chambers together with two associated electrically controlled valves enabling corresponding fluid connections to be selectively established.