Abstract: A shock absorber comprising a strut (1), a sliding rod (3) mounted to slide inside the strut, at least one gas chamber (13, 17) under pressure, an oil chamber (6) associated with the gas chamber, and an expansion chamber (5) connected to the oil chamber via expansion throttling valve (8), the volume of the expansion chamber (5) varying as a function of the extent to which the sliding rod is received in the strut. The shock absorber also includes an expansion short circuit passage (18) between the oil chamber (6) and the expansion chamber (5), the expansion short circuit passage having a cross-section which is greater than the flow section of throttling valve (8), and the shock absorber includes controlled closure partition (32) for closing expansion short circuit passage (18).

Abstract: A hydraulic circuit for aircraft braking, the circuit including wheel brakes (11) fed with hydraulic fluid by servovalves (8, 22) mounted in a normal circuit and in an emergency circuit. The normal circuit and the emergency circuit are selectively connected to the wheel brakes by switching devices (9) and protected from excessive loss of hydraulic fluid by hydraulic fuses (6, 24). The servovalves of the normal circuit are associated in pairs. The hydraulic fuses (6) of the normal circuit are disposed upstream from the servovalves (8) on lengths of line (5) which are common to each pair of servovalves. The devices (9) for switching from the normal circuit to the emergency circuit are disposed downstream from the servovalves (8).

Abstract: The present invention relates to shock absorbers including a rod slidable in a cylinder and a piston for determining at least two variable volume chambers, one of the two chambers including a first resilient member at a first pressure, and the other chamber containing a second resilient member at a second determined pressure, the second resilient member being suitable for being displaced in translation en bloc by an actuator chamber.

Abstract: The present invention is concerned with tilting-beam undercarriages.The undercarriage is characterized in that the shock absorber means (7) comprise a hollow cylinder (11) entered by a plunger stem (14) at its first end (12) and by a piston (18) at its second end, while the hollow cylinder (11) has a hinge member (22) onto which the beam (8) is hinged at a point C differing from the center of it and the piston (18) is connected to the beam at a point D differing from the point of hinge C.

Abstract: Thermal insulators (40,50) are each made of a material based on carbon fibers and subjected to low temperature heat treatment. One insulator (40) is disposed between a thrust means actuator (18) and a first brake stator (28a), and the other insulator (50) is disposed between a last brake stator (28b) and a brake retaining plate (30). The insulator (40) associated with the first stator (28a) is of comparable size to the stator.

Abstract: There is disclosed a mould for lost pattern casting. The shell of the mould comprises a graphite coating and a hydrocarbon binder. The binder comprises a polyol with at least three alcohol functions such as pentaerithritol.

Abstract: The method of controlling braking on a wheeled vehicle (such as an aircraft during landing) is applied to at least one wheel of the vehicle, which wheel has brakes and means for measuring the wheel speed. The method consists in a repeated two-period cycle comprising:a measuring period (0-t1, t2-t3) in which the wheel brakes are not applied and in which the true speed (A) of the vehicle is measured by measuring the linear speed (D2) of the wheel; anda braking period (t1-t2, t3- ) in which the said measured true speed is used in conjunction with a decleration value to estimate an approximate value of the vehicle speed (B1, B2), and in which the wheel brakes are applied in such a manner that the linear speed (D1, D3) of the wheel is caused to be less than the estimated speed of the vehicle by a predetermined function.

Abstract: Each rocking arm (9, 10) hinged to a shock absorber (7, 8) has a lateral extension (13, 14) extending at an acute angle a to one side of the shock absorber (7, 8). This extension (13, 14) is connected by a telescopic strut (15, 16) to the opposite end (7A, 8A) of the same shock absorber (7, 8) in order to shorten said shock absorber when the landing gear is raised, thereby reducing the space it occupies in the raised position.

Abstract: The present invention concerns processes for making composite materials.The process is characterized essentially by the fact that it consists in making a fibrous preform 1, in pre-treating this fibrous preform by a fluorine containing flux 3 and in wetting the said pre-treated preform by a light alloy.Utilization for the making of composite pieces with a fibrous armature such as carbon wet by a light aluminum-based alloy.

Abstract: The landing gear comprises: a rod including nested first and second tubes between which there slides a cylinder whose outer end supports a running gear; a strut surrounding the top of the rod and including a steering mechanism cooperating with a rotary tube disposed between the rod and the strut; and a fluid actuator constituted by at least one chamber between the strut and the rod and having a feed inlet only. The landing gear is particularly applicable to helicopters that are required to "kneel down" camel fashion, e.g., for storage in the hold of an aircraft carrier or a cargo plane.

Abstract: On a shaft (2) which carries a wheel there are mounted: firstly a toothed sector (3) which meshes with a rack (4) on a piston rod (5) which is a part of a double-acting hydraulic actuator (8); and secondly a cam (12) which acts on two rocking levers (13, 14) to apply a bolt (13B, 14B) against a stop face (10A, 10B) of the rod (5) when, by directly swivelling the wheel, the toothed sector (3) is disengaged from the rack (4).

Abstract: The low portion (9) of a landing gear strut (3) carrying running means such as a wheel (8) is capable of swivelling together with the running means relative to the strut. A system of cranks (17) receives the necessary force for swivelling the wheel during retraction and extension of the landing gear from a rod (13) which is fixed to the aircraft structure (2) at a point different from the point at which the strut (3) is fixed. The rod (13) is of variable length (piston and cylinder arrangement 31), and the crank system has a stop (33) against excessive swivelling. The arrangement is such that swivelling is restricted to a selected portion of the landing gear's travel, e.g. to ensure that the wheel enters the aircraft body at a particular degree of swivel.

Abstract: The method of controlling aircraft braking during landing on a runway as soon as the running gear of the main landing gear has made runway contact and prior to the nose gear making contact, comprises: determining the value of the nose-up angle .DELTA. of the aircraft as soon as it makes runway contact with its main landing gear; providing a signal representative of the value of the nose-up angle; and controlling braking of the aircraft by any appropriate braking apparatus as a function of a magnitude representative of the signal to ensure acceptable variation of said nose-up angle.

Abstract: The braking control system includes a generator for generating a first electrical control signal, a controllable fluid source suitable for delivering the fluid at a predetermined pressure at an outlet from the source, a slide valve for connecting the outlet of the source to a brake actuator, a circuit for measuring the value of the pressure at the outlet from the source, a circuit being suitable for delivering a second signal having a value representative of the measured pressure, and a controller for controlling the source of fluid as a function of the first and second signals in such a manner that the fluid pressure at the outlet from the source has a value which is a function of the first signal as corrected by the second signal.

Abstract: The nose wheel landing gear has the wheel (23) coupled to the rest of the landing gear by a deformable parallelogram (20, 37, 33, 13) which is located to one side of the wheel (23), the wheel lever (20) which supports the wheel is only slightly longer than the wheel radius. This arrangement enables the landing gear to be shortened when retracted without the wheel itself being offset sideways, thereby occupying less space overall.

Abstract: The present invention relates to landing gear. The landing gear has a strut (2) having one end pivotally mounted about a first axis (4) suitable for connection to the structure (1) of an aircraft. A lower portion (6) for supporting running gear (10) is pivotally mounted relative to said strut (2) to pivot about a second axis. A collapsible side brace (20) has one end suitable for connection to a first point (27) of the aircraft structure (1) for pivoting about a third axis (29) and a fourth axis (30) providing rotation with two degrees of freedom about said third and fourth axes respectively. The third axis (29) passes through said first point (27) being situated on a line which is not colinear with the first axis but which intersects said first axis at a second point (40). A pivot pin (33) is rotatable about a fifth axis (35), the fifth axis not being colinear with said first (4), third (29) and fourth (30) axes and being situated on a line which passes through said second point (40).

Abstract: The landing gear comprises a shock absorber (4) having a rod (6) slidable in a cylinder (6), a wheel (12) linked to the cylinder, a guide sheath (14) surrounding the shock absorber (4), releasably engageable means (17) for fixing the cylinder at least in rotation relative to the guide sheath (14), and a strut (21) surrounding the sheath. When the strut is retracted under the control of an actuator (42) a rod (80) draws the sheath (14) into the strut (21) thereby compacting the landing gear lengthwise, at the same time a helical groove (38) cooperates with a groove follower (40) to turn the sheath, and hence the shock absorber cylinder (6) and the nose wheel (12) so that the wheel lies flat inside the aircraft when retracted.

Abstract: A shock absorber including a cylinder (501), a rod (502) slidably mounted in the cylinder, and a piston (506) fixed to the rod and slidable inside the cylinder. The piston divides the cylinder into two oil-filled chambers (508, 514) and there is a third chamber (518) in the rod and including air to act as a hydraulic spring. Shocks tend to move the piston along the rod away from its equilibrium position therein, and the hydraulic spring tends to return the piston to its equilibrium position. Damping is provided by variable aperture channels between the first chamber (508) and the other two chambers (514 and 518). The channels comprise orifices (509 and 510) in a cylindrical wall of the first chamber (508) which overlap orifices in a movable cylindrical valve plate (527). A control shaft (540) leading out along the axis of the shock absorber serves to rotate the valve plate and to move it in axial translation.

Abstract: The shock absorber is characterized by the fact that it comprises a rod (1) sliding in a cylinder (2) through a piston (3) to determine at least two variable-volume chambers (4,6), ports (40,41) for placing the two chambers in communication, one of the two chambers (4) comprising first elastic fluid (44) at a first given pressure, the other chamber (6) comprising second elastic fluid (10) at a second given pressure, controllable according to at least one parameter, corresponding to a force to be absorbed.

Abstract: A two-way transducer for transfering power between two hydraulic circuits, e.g. to ensure uninterrupted hydraulic power in all the hydraulic circuits of a twin engined aircraft, even when one engine has failed. A body (1) has an elongate cavity (4) housing two barrels (14, 15) of cylinders (26) with pistons (28) slidably mounted therein. A common drive shaft (17) enables each barrel to drive the other. A wedge (16) located between the barrels provides two oblique surfaces (18, 19) for the piston heads to slide over. Sealing means (38, 39, 43, 44) to prevent fluid leaking from one circuit to the other. In operation one barrel operates as a swashplate type of motor driving the other barrel which then acts as a pump.