Abstract: Apparatus for automatically presenting a generally pre-needled textile sheet coming from an upstream module and intended to feed a cross-layer module, the apparatus comprising means for measuring the positions of the longitudinal edges of the textile sheet, means for adjusting the width of said textile sheet, means for adjusting the position of said textile sheet, and processor means responsive to the position measuring means to control the adjustment means in real time in such a manner that the textile sheet presents determined width and position.

Abstract: Apparatus for automatically controlling the spreading of a textile sheet made up of a plurality of tows coming from a tow feed module and serving to feed a drive module, the apparatus comprises means for measuring the positions of the longitudinal edges of each tow, means for individually adjusting the width of each tow, means for individually adjusting the position of each tow in a direction perpendicular to a tow advance direction, and digital processor means responsive to said position measuring means to control the adjustment means in such a manner that the textile sheet presents determined width and position.

Abstract: A gas diffusion electrode comprises a cloth (12) of activated carbon fibers having a first face coated in a hydrophobic material (14) and a second face on which particles of catalyst (16) are fixed directly and are dispersed in substantially uniform manner over the fibers. The electrode can be used in an electrochemical cell of a proton exchange membrane fuel-cell battery, or in an electrochemical reactor, e.g. for making chlorine and caustic soda.

Abstract: The invention relates to an architecture for a hydraulic braking system suitable for an aircraft of the type having at least one group of main landing gear units, each landing gear unit comprising a determined number of wheels each provided with a hydraulically actuated brake, the or each landing gear group being associated with a hydraulic circuit provided with hydraulic equipment and adapted to deliver hydraulic fluid under pressure to all of the brakes of the landing gear group, the hydraulic fluid being pressurized by at least one aircraft pressure generator system associated with an aircraft hydraulic fluid supply. According to the invention, accumulators are connected on the or each circuit in sufficient number for each accumulator to feed two pairs of brakes, each pair of brakes being mounted on a distinct landing gear unit, and an electrically-driven pump being arranged to maintain a predetermined pressure level in all of the accumulators of the circuit in question.

Abstract: A carbon fiber fabric having large specific surface area is made using a rayon precursor, and a catalyst is fixed on the fabric by impregnation or by cationic exchange. The carbon fiber fabric has pores with a mean size lying in the range 0.3 nm to 3 nm, a carbon content greater than 99%, and a high density of functional groups per unit area which favors the dispersion of metal catalyst in the form of fine particles and which is good for highly selective catalytic reactions in fine chemistry.

Abstract: A machine for needling a textile structure made up of a plurality of superposed layers comprises a vertically movable needling table, a needling head having a determined number of barbed needles and disposed vertically above the needling table, and drive means for imparting vertical reciprocating motion to the needling head, defining a low point of maximum penetration of the needles. Measuring means are provided in the machine located in the needling head to measure the position of the top surface of the textile structure at the low point of maximum penetration of the needles. The measuring means are preferably disposed in a midplane of the needling head perpendicular to an advance direction of the textile structure.

Abstract: In a circular needling machine for needling an annular preform and comprising both a vertically movable needling table serving as a horizontal support for said annular preform, and a needling head having a determined number of barbed needles disposed over the needling table in a needling zone and driven with vertical reciprocating motion, provision is made for the annular preform to be placed directly on the needling table and for it to be driven in rotation on the needling table by drive means while the needling table remains rotationally stationary during said rotation. The drive means comprise a set of conical friction rollers kept continuously in contact with the annular preform.

Abstract: A machine for needling a textile structure built up from a wound strip of material to be needled that is delivered by strip supply means comprising a storage drum containing said wound strip of textile material, an unwinding assembly for continuously extracting said strip from said storage drum, and a helical chute or “twist” for taking up said extracted strip unwound from said drum and for bringing it up to a needling table where there are friction drive means. The storage drum and the helical chute have the same axis C as the needling table.

Abstract: The carbon fibers present a mean lattice surface spacing (d002) not less than 0.36 nm, preferably 0.38 nm, at a crystallite size such that the mean height (Lc) lies in the range 0.7 nm to 0.3 nm and the mean width (La) lies in the range 2 nm to 6 nm, and it presents total porosity lying in the range 10% to 30%. The electrode is preferably a rayon-precursor carbon cloth and it constitutes the anode (10) of a secondary cell having a cathode (20) which includes lithium enabling lithium ions to be inserted and de-inserted, and an electrolyte (30).

Abstract: A needled fiber structure is made by stacking fiber plies on a platen, by needling the plies as the stack of plies is built up by means of needles driven with reciprocating motion in a direction that extends transversely relative to the plies, and by varying the distance between the platen and an end-of-stroke position of the needles while building up the stack so as to obtain a desired distribution of needling characteristics through the thickness of the fiber structure. The instantaneous force exerted during needle penetration is measured (sensors) and a magnitude representative of needling force or penetration energy is evaluated on the basis of the instantaneous force, and the evaluated magnitude is verified for compliance with at least one predetermined condition to monitor proper operation of the process or to act on the way the distance between the platen and the end-of-stroke position of the needles is varied.

Abstract: A machine for needling a textile structure built up from a helical strip delivered by strip supply means, said machine comprising a needling table, a needling head, cutting means for cutting the helical strip, and conical roller drive means for rotating said strip on the needling table, at least a fraction of said conical roller drive means being retractable so as to release an empty space on said needling table enabling ejector means to remove the textile structure from the needling table.

Abstract: The invention relates to a hydraulic pump having axial pistons, the pump being of the type having intersecting axes, and comprising a rotary rotor with a central axis co-operating with an associated distribution seat via a bearing surface that is substantially perpendicular to said axis, said rotor presenting a plurality of axial bores slidably receiving corresponding pistons. According to the invention, a driver separate from the rotor is provided to rotate about an axis of rotation that essentially coincides with said central axis, said driver serving firstly to center and rotate the rotor about said axis of rotation, and secondly to apply resilient thrust to press the bearing surface of the rotor against the distribution seat.

Abstract: The friction device comprises a non-rotary casing (50) in the form of a cage in which there are received a thrust structure (30), a set of friction disks (21, 22, 23, 24, 25) on a common axis, and a backing structure (40), the casing having a peripheral wall provided with ventilation openings (54). The friction device is actuated by a pneumatic actuator (60) mechanically connected to the central portion of the thrust structure through a central opening in an end wall (51) of the casing. Thermal insulation is arranged between the set of disks (21, 22, 23, 24, 25) and the outside of the casing adjacent to the end wall provided with the bearing unit (11) for the rotary shaft (10), and comprises at least one heat barrier (76-77, 78-79) situated at the bearing unit (11).

Abstract: A rotor disk (20) is arranged between two stator disks (30, 40; 130, 140), the disks being made in thermostructural composite material at least for the wear parts. A first supporting structure (50, 150) has a bell shape with a bottom part (52) whereon rests the first stator disk (30, 130) and part of the skirt (70, 170) linked to the bottom part (52) and encloses the disks (20, 30, 40), the bell-shaped structure having cooling means (170, 174) for evacuating the heat generated by the mutual friction of the disks. A second supporting structure (80, 180) has a part in the shape of an annular support plate whereon rests the second stator disk (40, 140); and the bell-shaped structure bottom part (52) and the support plate (80, 180) are provided with cotters (60) or radial ribs (84) co-operating with the corresponding radial housings (36) formed in the outer surfaces (33, 44) of the stator disks (30, 40; 130, 140) to block the latter in rotation relative to the supporting structures (50, 150; 80, 180).

Abstract: The invention relates to apparatus for braking a set of aircraft wheels, the apparatus comprising a normal hydraulic circuit and an emergency hydraulic circuit, both circuits leading to each of the various brakes via associated brake valves. According to the invention, the brake valves of the normal circuit and/or of the emergency circuit are constituted by direct drive valves that are electrically controlled by an associated electronic control unit.

Abstract: A three-dimensional fiber structure is formed by superposing layers of felt and by bonding them together by needling, then the structure is compressed to obtain a preform having a fiber volume fraction of not less than 20%. The preform is held in its compressed state by being impregnated with a liquid composition containing a bonding agent capable of bonding the fibers of the preform together. Thereafter, the preform consolidated in this way is densified, e.g. by chemical vapor infiltration.

Abstract: A fabric made of fibers of a carbon-precursor cellulose material is impregnated with a composition containing at least one inorganic ingredient having a function of promoting dehydration of cellulose, and the fabric is subjected to heat treatment. This treatment consists in raising temperature at a speed lying in the range 1.degree. C./min to 15.degree. C./min followed by keeping the temperature constant in the range 350.degree. C. to 500.degree. C., and it is followed by a step of washing the fabric. This produces directly an activated fabric of carbon fibers having a specific surface area of not less than 600 m.sup.2 /g, without subsequent activation treatment at a higher temperature.

Abstract: The invention encompasses a friction-in-oil device having a plurality of coaxial disks comprising metal rotor or driving disks, metal stator or driven disks, and loose disks of carbon/carbon ("C/C") composite material, each loose C/C disk lying between a metal rotor or driving disk and a metal stator or driven disk. Each loose C/C disk is centered by a bearing surface formed in an adjacent metal rotor or stator disk, which bearing surface has passages for feeding oil to the interface between the loose C/C disk and the metal rotor or stator disk.

Abstract: The invention relates to an arrangement of carbon brake disks for an aircraft brake unit comprising stators coupled to a torsion tube alternating with rotors coupled to the corresponding wheel. The arrangement is organized in two configurations corresponding to operation over two successive wear strokes of the pistons of the brake ring, with a first of the configurations comprising a central group of rotors and stators arranged between a front lateral stator and a rear lateral stator, and with a second of the configurations comprising the same front lateral stator and the same rotors and stators of the central group, but arranged between a spacer disk of thickness less than the wear stroke of the pistons, and a new rear lateral stator of thickness greater than that of the preceding rear lateral stator.

Abstract: The invention relates to a reinforcement device for reinforcing the open slots of a carbon brake disk. According to the invention, each slot is provided both with a U-shaped insert whose two lateral limbs are disposed to face the lateral faces of the corresponding coupling bar, and with two channel-section caps that extend towards each other so as to surround the two lateral limbs of the insert completely, each cap having a free end edge that occupies a plane that is parallel to the corresponding inside face and that, on initial assembly, stands slightly projecting relative to said face, thereby enabling said free end edge to be brought exactly into the plane of said inside face after the brake has been used during a running-in period.