Abstract: The apparatus comprises a body (1) provided with three point-contact feelers (12, 13) which open under the action of a spring (19) and close under the action of a lever (20) via a rod (14) and a spacer stop (15). A displacement pick-up (22) and an electronic circuit (25) convert the displacement of the feelers into a measurement signal which is representative of the diameter of the circle which they define. The electronic circuit comprises a minimum memory (31) to memorize the minimum value of the measurement signal, a member (39) for displaying this value (39) and a measurement-initialization switch (32). After the feelers, folded together, have been introduced into the bore, the lever is released, the switch is actuated, and the apparatus is moved in all directions by the operator in order to cause the plane of the feelers to pass in a diametral plane of the bore, this passage generating the minimum value displayed which is representative of the actual diameter of the bore.

Abstract: An instrument for the measurement and verification of linear dimensions includes a body equipped with external and internal feelers, a perch mounted in a slideway in the body and equipped with external and internal feelers cooperating with those of the body, and independent depth gauge mounted in a second slideway of the body, and a feeler rod mounted in a third slideway of the body, and cooperating with a contact piece fastened with an inner face of the external feeler of the perch. A movable member of a measurement transducer is selectively connected to the perch, to the gauge and to the feeler rod by a selective coupling device. In turn, a display device with zeroing control is connected to the measurement transducer.

Abstract: A hand-held interior gauge for measuring a bore includes a body provided with a measuring head capable of being introduced into the bore, and a measuring transducer connected to a movable feeler and adapted to produce output signals representative of the displacement of the movable feeler. The gauge also includes a mechanism for immobilizing the measuring head while in the bore, such that the feeler is movable angularly and radially in a surface limited by a circumference contained in a plane perpendicular to the axis of revolution of the bore, once the measuring head is immobilized. A driving mechanism forming a portion of the interior gauge coordinates the angular and radial movement of the movable feeler, and the output signals from the feeler are provided to a calculator which, in turn, provides intelligence information to an automatic display device for displaying the diameter of the bore.

Abstract: In a precision dial measuring instrument having a coil-spring shock-absorbing movable unit provided between a pinion and a coaxial gear wheel of the transmission step-up mechanism arranged between the movable indicating member and the feeler of the instrument, the transmission step-up mechanism further includes a system for taking up of play by preliminary elastic stress of its train gear wheels.

Abstract: A shock absorbing device for use in dial measuring instruments comprising a balance lever interposed between a pinion and a coaxial toothed wheel of the multiplier mechanism disposed between the movable indicator member and the movable feeler of the instrument, said balance lever being pivoted on the common axis of said pinion and toothed wheel and intercepting during its pivotal movement in one and the same direction a first radial driving finger integral with an arm connected to the pinion and a second radial driving finger integral with said toothed wheel, a resilient liaison being formed between the balance lever and the radial driving fingers by the opposed action of the ends of at least a spiral spring connected at its inner end to said balance lever.

Abstract: In a micrometer head for an instrument for measuring internal dimensions there is included a casing in which at least one measurement contact piece having an inclined base is radially mounted in a slot or groove. The contact piece is driven by the axial displacement of a measuring cone and is maintained in contact with the inclined lateral surface of the cone by means of a return member. The axial displacement of the measuring cone, the base of which is guided in an axial cylindrical recess of the casing, is effected by the thrust of a spindle which has a micrometer screw mounted thereon, the screw being engaged in a threaded member connected to the casing. The cone and spindle have coaxial axes of rotation, and the cone, spindle and micrometer screw are so arranged that the path of movement of the inclined base of the contact piece on the cone is in the form of a tapered ramp having a long length and shallow inclination, the movement being caused by the combined axial and rotational movement of the cone.