Abstract: A releasable connector for interconnecting a first part and a second part, at least one of the parts being subjected to high stresses in particular of vibratory origin and of thermal origin, the connector comprising a sealing ring compressed between the two parts, a main lip formed on the first part to be interconnected, and at least one connection part for exerting a retaining action on the main lip relative to the second part to be interconnected and for compressing the sealing ring. The connector further includes an intermediate ring provided with a flange and constituted by at least two lengths, the intermediate ring being interposed between the main lip and the connection part and being made of a material of low thermal conductivity.

Abstract: The present invention relates to the acquisition of seismic signals at different levels in a borehole, in response to the generation of seismic waves by a source placed on the surface or in the vicinity of the surface. The acquisition is carried out by means of a sonde suspended in the borehole from a cable and equipped with an anchoring pad. At each acquisition level, the pad is anchored in the borehole wall to couple the sonde to the formation, and then the pad is released from the wall once the acquisition is over. The signals acquired are then sent to the surface by means of the cable. The force with which the pad is anchored in the wall is controlled by means of a feedback arrangement which includes a sensor arranged in the pad itself. During the sonde movements from one level to another, the pad is kept in contact with the wall.

Abstract: A gantry support for supporting a roof of a passage includes two parallel supporting units each having a lower frame provided with articulated tracks and an upper frame carried by props and two cross-members. The two cross-members carry an intermediate upper frame in the form of a beam which is slidable on guide elements and adapted to be clamped to the roof by small jacks. As the support advances the beam remains clamped against the roof of the passage until the beam reaches an end stop. The small jack is then released and the beam slidably advanced along the guide elements by means of a further jack.

Abstract: The invention relates to a thrust device using a plurality of hydraulic jacks, and to the automatic control of a plurality of thrust jacks.Two differential jacks have resetting chambers which are permanently under hydraulic pressure. Associated with each jack there is a self-locking piloted valve placed in the active position by a push-rod at the end of a work stroke of the piston of the jack and restored into the inactive position by a piloted valve actuated by a push-rod 39 at the end of the return stroke of the piston to its starting position. In the active position the self-locking piloted valve controls the isolation from the supply of all the work chambers and the venting of the associated work chamber 14.

Abstract: A ball joint for transmitting forces between the prop and the head-piece of a support unit has a spherical head received in the spherical internal surface of a dome. The dome is enclosed by a spherical ring which is fastened to the head. The rod of a prop carries a pivot which is mounted with radial clearance in a cylindrical cavity located within the sphericl head.

Abstract: A device for causing translation of a machine carried on a sledge surrounded by an articulated track comprises a pushing member provided on a jack supported by the sledge, the pushing member cooperating with abutments provided on the inside of the track. The track comprises a plurality of articulated shoes each formed of two L-shaped half-shoes fastened together so that the shorter branches thereof are spaced from one another and are substantially parallel to the direction of movement of the track. Each abutment is carried by the shorter branches of each shoe whereby the passage formed by the space between the two shorter branches is at a position corresponding to that of the respective abutment.