Caliper (redirected from brake calipers)

caliper

Instrument that consists of two adjustable legs or jaws for measuring the dimensions of material parts. Spring calipers have an adjusting screw and nut; firm-joint calipers use friction at the joint to hold the legs unmoving. Outside calipers measure thicknesses and outside diameters of objects; inside calipers measure hole diameters and distances between surfaces. Hermaphrodite calipers, which have one leg bent inward and one straight leg ending in a sharp point, are used for scribing lines at a specified distance from a flat or curved surface. See also micrometer.

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calliper (US), caliper

1. an instrument for measuring internal or external dimensions, consisting of two steel legs hinged together

2. Med a splint consisting of two metal rods with straps attached, for supporting or exerting tension on the leg

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caliper [′kal·ə·pər]

(design engineering)

An instrument with two legs or jaws that can be adjusted for measuring linear dimensions, thickness, or diameter.

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caliper

caliper

An instrument, resembling a pair of dividers, with adjustable legs for measuring the diameter or the thickness of bodies. Also see inside caliper and outside caliper.

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Caliper 

a device that is lowered into a bore hole on a cable to determine the diameter of the hole. Mechanical and ultrasonic calipers are used.

The most commonly used mechanical caliper consists of three or four lever feelers (probes), which are pressed against the walls of the bore hole by springs, and a rheostat whose sliding contact is connected to the feelers by means of pushrods. A change in the diameter of the borehole produces a proportional change in the resistance of the rheostat. This resistance is measured on the surface and, as a result, a curve is produced showing the change in the diameter of the borehole from the face to the mouth of the hole. Recent models are equipped with a controlled lever device that can be opened and closed repeatedly on command from the surface.

An ultrasonic caliper is a hydrolocating device with two directional electroacoustic transducers located on opposite sides of the borehole instrument. Each transducer operates alternately as an ultrasonic oscillation emitter and detector. The time interval between the moments of the transducer’s emission and its reception of the ultrasonic pulse reflected from the wall of the borehole is measured on the surface. Since the interval is proportional to the distance from the device to the borehole wall, two longitudinal profiles of the borehole are produced, characterizing its diameter.

Since the cross section of a borehole is usually noncircular, instruments have been developed that permit measurement of the size and shape of the cross section.

V. T. CHUKIN