Abstract: A stage apparatus having a rotary table and a method of operating the same are provided. The stage apparatus includes a base, a stage which is rectilinearly movable on the upper surface of the base, and a rotary table which is rotatable on the stage and on which a workpiece is to be placed. Therefore, a larger workpiece can be effectively manufactured using the stage apparatus.

Abstract: An improved wheel alignment apparatus having a fixed support structure and a pair of cylindrical rollers communicating with the support structure, wherein the rollers support the wheels of a motor vehicle and allow rotation of the wheels while maintaining the motor vehicle in an essentially stationary position. The rollers are supported on a float plate utilizing a layer of pressurized air pumped below the float plate to allow the float plate to move along a substantially flat horizontal surface to allow the vehicle to settle into a steady rotational mode. The front of the float plates are connected through a series of linkages and a connecting rod to a linear actuator pivoting about a vertical axis. The linear actuator retracts to straighten the connecting rod which centers the float plate to a limited motion along the horizontal surface, and extends so that the connecting rod may pivot about a longitudinal axis and turn with the float plate and wheels of the vehicle.

Abstract: A tool presetting device comprises a carrier device for rotatably holding a tool. The tool is received in a bearing bushing which defines a bearing axis and provides a rotationally symmetrical bearing surface wherein said tool is enabled to be rotated in a desired measuring and setting position. An air suspension can be built up for enabling rotation of the tool. To this end, a source of pressurized air is provided which enables a certain throughput of air. At least one air outlet opens at the bearing surface, while receiving pressurized air from the said source. A switching device either admits or prohibits access of pressurized air to the air outlet. A throttle valve is connected to the source of pressurized air for limiting the throughput of air.

Abstract: An air-probe structure of an air-gauge nozzle that defines an air-probe bore having an elongated, relatively small-area output tip (e.g., 0.3.times.1.3 millimeters) situated at the air-probe structure's output end. Such an air-gauge nozzle is useful in controlling the distance between the bore's output tip and a rowbar workpiece (employed in an optical microlithographic pole trimming step of the fabrication process for thin-film heads) in accordance with the air pressure measured by the air gauge. The air-probe structure's output end preferably also comprises a relatively large-area protective manifold (e.g., 6.times.7 millimeters) surrounding the elongated, relatively small-area output tip.

Abstract: A plug gauge for checking shape errors, in particular, the roundness of a valve seat. The plug gauge comprises seating surfaces adapted for cooperating with the surface of the valve seat, and a pneumatic circuit with an annular nozzle at the seating surfaces. The gauge comprises two coaxial cylindrical elements, one of the two housed within the other, that can reciprocally translate in an axial direction and that comprises associated resting surfaces, such that both cylindrical elements may rest on the seat surface to be checked. The annular nozzle is substantially defined by an internal and an external cylindrical portion of said two reciprocally movable elements.

Abstract: A measurement probe has a plurality of movement directions, and is constructed with one or more pneumatically actuated locking mechanisms, each of which can be selectively actuated to prevent movement along one of the movement directions. The pneumatic actuator has a flexible diaphragm which is expanded by application of air pressure to move a spring member, thus engaging a locking element connected to the spring member with a receiving element to prevent movement of the probe in the direction associated with that locking mechanism. A pneumatic control system is provided to control the locking mechanism(s) in accordance with operator desires, a predetermined program, or operating requirements of an electronically controlled machine associated with the probe.

Abstract: A fixed length telescoping measuring stick that is self supporting and includes an inner telescoping ruler and two-way level combination. A divided encasement comes together via an air-damped cushion provided by a controlled release air lock that is automatically effective to protect the user. This air cushion damper is in combination with a friction position locking knob for either right or left handed users.

Abstract: An apparatus for simultaneously measuring the thickness of a bottom wall and the inside diameter of a bottoming hole. The apparatus includes a measurement auxiliary unit; a measurement head removably mounted at a lower end portion of the measurement auxiliary unit, the measurement head having an outside diameter fittable in a bottoming hole of a workpiece such as a tappet; a nozzle, provided in the measurement head, for jetting outward a compressed air supplied from an air micrometer; and an electric micrometer, provided over the measurement auxiliary unit, for detecting a vertical displacement of the measurement auxiliary unit.

Abstract: A tapped hole measuring apparatus available for automatically measuring the major diameter, minor diameter, effective diameter and depth of a tapped hole. The apparatus comprises a measuring stylus with at least two air discharging ports which can take inserting movement into the tapped hole. The apparatus separately measures the variations of the back pressures of air supplied to the air discharging ports, and converts the back pressure variations into electric signals and stores them. Also included in the apparatus is a configuration calculating section for comparing the variation of the electric signal from the tapped hole with a variation of electric signal from a reference tapped hole to obtain the configurational dimensions of the tapped hole being measured.

Abstract: The plug comprises an elongate member and at least one measurement ring mounted with radial play on the elongate member and comprising at least one pair of diametrically opposite measurement nozzles fed with gas under pressure, and also at least three centering nozzles disposed around the periphery of the measurement ring on radii that define equal angles between one another, the centering nozzles being fed with gas under pressure independently from the measurement nozzles.

Abstract: A method of measuring a length of a conduit comprises the steps of: supplying air into a conduit to insert a filamentary body into the conduit by flow of the air; detecting arrival of a forward end of the filamentary body at an outlet of the conduit; and measuring the length of the conduit from the length of the filamentary body inserted into the conduit. An apparatus for measuring a length of a conduit, comprises an air supply device for supplying air into the conduit; a filamentary body including a wire and a plurality of elastic large-diameter members attached to the wire; and a device for detecting that a forward end of the filamentary body arrives at an outlet end of the conduit, where the length of the conduit is measured from the length of the filamentary body inserted into the conduit.

Abstract: A method of measuring a length of a conduit comprises the steps of: supplying air into a conduit to insert a filamentary body into the conduit by flow of the air; detecting arrival of a forward end of the filamentary body at an outlet of the conduit; and measuring the length of the conduit from the length of the filamentary body inserted into the conduit. An apparatus for measuring a length of a conduit, comprises an air supply device for supplying air into the conduit; a filamentary body including a wire and a plurality of elastic large-diameter members attached to the wire; and a device for detecting that a forward end of the filamentary body arrives at an outlet end of the conduit, where the length of the conduit is measured from the length of the filamentary body inserted into the conduit.

Abstract: A continuous air flow probe transducer gage assembly which is configured to permit a continuous selectively controlled flow of air therethrough so as to selectively actuate a spring-biased air piston probe slidably mounted therein from its retracted rest position into its extended soft contact measuring position against a part being measured. The continuous air flow probe transducer assembly is adapted to be a part of a computer controlled system whereby several variable air flow modes are delivered therethrough so that selective rest position air flow modes, high volume air flow calibration modes and operative soft contact air flow measuring modes are used to actuate the probe transducer in its operative use environment.

Abstract: The centering device for a mechanical probe comprising a driver and two restoring member acting thereon in opposite directions, wherein only one, possibly multipart, stop is provided for a first restoring member. In the position of rest, the first restoring member lies against the stop exerts, at least near the position of rest, a restoring force twice as great as that exerted by the second restoring member. Springs or fluid pistons are provided as restoring members. They can briefly exert a shaking force on the driver.

Abstract: The invention comprises a machine having air bearings and a control apparatus for turning off one or more of the air bearings when the machine has been idle for a specified time period.

Abstract: A method of precisely calibrating a spindle position with respect to a drilling apparatus worktable. The drilling apparatus includes a control device, which calculates an expected relative position of the spindle and the worktable based upon predetermined information, and the controlled movement of the spindle relative to the worktable. The method includes positioning the spindle in a first position, empirically determining the position of the spindle with respect to the worktable in both a first and a second direction, and determining a "correction factor" between the expected spindle position relative to the worktable at the first position and the empirically determined spindle position relative to the worktable in the first and second directions.

Abstract: A flexible, modular gage system is presented for statistical process control to compare the delta dimensional difference between a master part with known dimensional values to one or more manufactured production parts. A main feature of the invention is the gage that holds measurement devices, such as a transducer probe. The components of the modular auto gage allow position of analog, digital or mechanical measurement devices in virtually any position, being limited only by the part-holding device or interference with other measurement devices. Measurement devices once positioned can remain stationary or attached to a precision pneumatic slide. The pneumatic slide retracts the measurement device to allow easy loading and unloading of the part to be gaged.

Abstract: The present invention relates to a spot welding inspecting apparatus for inspecting a weld between two metal plates which are subjected to spot welding without destroying the metal plates or weld. A pair of knife gauges having an interval therebetween larger than the diameter of the weld are inserted between the welded metal plates by a continuous impact of the hammer which is driven by a compressed air and pushed between the metal plates so as to clamp the weld. Thereafter, the piston is moved so that the knife gauges may approach the weld to indicate the distance between the knife gauges with the index.

Abstract: A displacement-measuring apparatus including a cylindrical housing, a static-pressure bearing located within the housing, a probe shaft supported by the bearing so that the bearing is supported in non-contact fashion and is movable in the axial direction, and a stylus connected to the end of the probe shaft so as to apply pressure to an object. Part of the static-pressure bearing includes a hollow cylindrical bush and at least two restriction holes formed in the bush and equidistantly spaced along the circumference of the bush. These holes supply air into the gap between the probe shaft and the bush. The static-pressure bearing further includes a first set of grooves formed in the inner surface of the bush that extend along the axis of the bush so that each opposes at least one restriction hole, and a second set of grooves formed in the circumferential surface of the probe shaft that extend along the axis of the probe shaft.

Abstract: The planarity of semiconductor device pins is measured simultaneously by multiple pneumatic comparator circuits by detecting pressure changes proportional to pin position.

Abstract: A magnetic compass has an instrument body adapted to be held level by a gimbal mechanism and having a vertical cylinder member, a spherical or semi-spherical float body on the upper end of the cylinder member and having a spherical surface facing downwardly into the upper end of the cylinder member, a magnet at a bottom center of the float body for making the center of gravity of the float body near the bottom center of the float body, a graduated azimuth scale on the float body, a lubber's line indicator on the surface of the instrument body surrounding the float body, and an air blowing device operatively associated with the cylinder member for blowing rectified air upward through the inside of the cylinder member with a force sufficient for making the float body float stably on the upper end of the cylinder member and out of contact therewith for enabling the float body to freely turn in response to geomagnetic force.

Abstract: An instrument for measuring a gap between it and an opposing surface, comprising a gas conduit having an inlet and an outlet, a sensing orifice in the outlet, a gas pump connected to the inlet for applying an alternating pressure to the gas conduit so that puffs of gas are directed from and drawn back to the sensing orifice. A sensor is in fluid communication with the conduit responsive to a physical property of the gas responsive to a condition determined by the gap size and a circuit is responsive to the sensor to provide a signal respective to the physical property.

Abstract: An apparatus for maintaining the end of a probe carrying a sensor, such as an eddy current probe, a predetermined distance from a workpiece includes a housing in which a piston is permitted to move. Air under pressure, introduced into a first chamber formed within the housing, acts on a first surface of the piston to urge it toward the workpiece. An air bearing is used to permit the almost friction free axial movement of the piston within the housing. Some of the air passes from the first chamber through a restricted opening in the piston into a second chamber and is vented toward the workpiece. The pressure in the second chamber will vary as a function of the distance of the end of the probe to the workpiece surface. The piston is provided with a second, larger, surface area exposed to the variable pressure in the second chamber, and as a result, the piston is urged away from the workpiece.

Abstract: A gauge for measuring in situ the diameter of a borehole in salt or other ft creeping rock types is provided so that changes in borehole structure can be detected. The gauge comprises a cylindrical body insertable lengthwise into a borehole and having an internal channel wherein sensors can be displaced outwardly when air is directed into the gauge, two air displacement sensors located in the channel having slotted keyways at their inner ends which form an orifice proportional to the distance between the sensors, a pneumatic device capable of providing a stream of air into the gauge body, and a flow meter for measuring air flow through the gauge body. The borehole diameter is determined by directing a stream of air into the gauge body and measuring the air flow which will be proportional to the distance between the sensors when displaced outwardly against the borehole walls. The gauge is advantageous in that it does not itself create artificial stresses or deformations in the borehole walls.

Abstract: The described invention is a precisely adjustable transporter for moving a reticle past an optical slit as a step in the production of semiconductor wafers. The reticle stage rides along a pair of optically flat planar, intersecting, bearing surfaces supported by air bearings on each bearing surface. Pressurized air and vacuum may be simultaneously employed to effect substantially friction-free motion while preventing displacement from the bearing surfaces. Axial adjustments on each air bearing permit precise adjustment of the reticle stage and reticle.

Abstract: An air gage assembly for testing for the presence of threads in holes in a workpiece or for the presence of the holes per se. The assembly includes a hollow housing open at one end and closed at the other end; an elongated probe assembly; means pivotally mounting the probe assembly in the housing in a location intermediate the ends of the probe assembly with one free end of the probe assembly positioned within the hollow of the housing and the other free end positioned outside of the housing; means for supplying air to the hollow of the housing; and means for passing the air centrally through the probe assembly for discharge through the other free end of the probe assembly and against the threaded or unthreaded wall of the hole to be tested.

Abstract: A device and a system for ascertaining dimensions includes at least one gaging block held by negative pressure to a workpiece. The gaging block has a body with a first face and a second face. The first face includes a recess portion therein and the second face defines a measurement reference surface. The body includes a port in communication with the recess portion and adapted for communication with a negative pressure generating device such as a vacuum pump. The gaging block is held by negative pressure in intimate and highly accurate contact with a workpiece in order to provide a reference point for measurements that might for a variety of reasons be most difficult to obtain.

Abstract: An aligning system for aligning a first object and second object with each other by moving them as a unit through a fluid bearing is adapted to accomplish a coarse alignment by displacing the first and second objects relative to each other and to attain a fine alignment by controlling the supply of pressure to the fluid bearing.

Abstract: A tool holder has on its lower end an inverted, frusto-conically shaped bearing surface which is releasably seated coaxially in a correspondingly shaped opening which is formed in the upper surface of a stationary support. Intermediate its ends the bore wall which defines the frusto-conically shaped opening in the support has therein a shallow, circumferential recess, which is connected through a port in the support with a supply of fluid under pressure. In use the lower end of the tool holder is held in the opening in the support solely by gravity; and a tool, which is mounted in the upper end of the holder, is positioned adjacent a conventional gauging device which can measure tooth height and tool runout. Fluid under pressure is supplied to the recess in an amount sufficient to cause the tool holder to be elevated slightly without breaking the seal between the recess and the frusto-conically shaped bearing surface on the tool holder, whereby the tool holder can then be readily rotated manually.

Abstract: A dimensional measuring and checking machine mounts a bridge structure (12) on legs (22) which are supported on a base (10) by air bearings. The varying forces due to travel of a probe mounting carriage (24) create vertical displacements of the bearings and movement of the bridge (12) out of alignment. To compensate for this, and thus enable high accuracy measuring, a chain (34) moves with the bridge (12), rotating a spindle (42) at one end of the machine, and thus moving the legs (22) at that end so levers (48) and pivot blocks (52) vary the height of the bridge (12).

Abstract: A coordinate measuring machine (10) having a vertically movable probe (41) supported from the bottom of a probe arm (42), the weight of which is offset by an improved pneumatic counterbalance (50). The pneumatic counterbalance is adapted to use a source of pressurized air acting upon a spherical piston (54) which is connected to probe arm (42). Spherical piston (54) fits with a close tolerance in cylinder (52). A rigid bracket (58) is connected to the top of probe arm (42). Piston rod (56) connects spherical piston (54) to a spherical bearing (53) in rigid bracket (58). A precision pressure regulator (70) having a relatively small capacity is provided to insure only a small change in the counterbalance force as the spherical piston (54) moves within cylinder (52). Regulator (70) is adjusted to provide make up air for the air which leaks past spherical piston (54).

Abstract: A probe for sensing the position of an object relative to a reference point includes a contact tip extensibly mounted on a probe body by means of a piston assembly which transmits minimal force to the object through the tip after the tip contacts the object. The piston assembly includes a fluid driven piston which is normally spring biased to a retracted position. The tip is mounted on one end of a shaft which is slidably mounted on the piston so as to be displaced relative to the piston only after the tip contacts the object. The other end of the shaft forms the core of an LVDT which transforms linear displacement of the shaft into electrical signals indicative of the position of the object relative to the reference point.

Abstract: A coordinate measuring machine (10) having a vertically movable probe (41), the weight of which is offset by an improved pneumatic counterbalance (50). The pneumatic counterbalance system (50) is adapted to use a source of pressurized air (72) acting upon a ball piston (54) which is directly connected to a probe arm (42) which supports the probe (41). An accumulator (60) having a capacity large enough to insure only a small change in the counterbalanced force as the ball piston (54) moves within its cylinder (52) is provided. A valve (70) is provided in the connection of the air supply (72) to the accumulator (60). The valve (70) is adjusted to provide make up air for the air which leaks past the ball piston (54). Preferably, the accumulator (60) is formed as a pressurized plenum (60) which surrounds the cylinder (52).

Abstract: a precision measuring apparatus (0) defining a measuring interval sealed from environmental influences comprises a shielding housing (10) surrounding a measuring interval and defining within the housing wall a slit (10a) oriented along the measuring interval, a movable member (11) attachable to a measured object and movable along the measuring interval, a carrying member (1a) attached to the movable member (11) and extending through the slit (10a), fluid bearings (12b) interposed between the movable member and the shielding housing to form a bearing gap (12) therebetween and to movably support the movable member (11) on the shielding housing (10) substantially without friction, and sealing fluid (14c) positioned in the bearing gap (12) to seal the slit (10a). The apparatus further includes a fluid supply means (14) for supplying sealing fluid (14c) such as vacuum oil, to the bearing gap (12), and means (18) for evacuating the shielding housing (10).

Abstract: A carefully dimensional drift is passed through a pipe section by fluid pressure to assure that the pipe is round and straight and of the right dimensions. The drift is light weight with an elastic contact surface, preferably of 70-D durometer hardness urethane, and thus is easily handled, adaptable to the fluid transit through the pipe and offers very long wear.

Abstract: A gage for directly measuring the deviation in cross sectional area of a passage from a nominal value employs a hydraulic system having pistons operatively engaged therewith. The pistons move in response to movement of passage contacting finger elements and the hydraulic system responds to piston movement to generate a measure of the passage area. At least one set of the finger elements has rotatable passage contacting members, each member having an elongated passage contacting surface. Each member rotates about a respective axis positioned to keep the center of each contact surface in a fixed position relative to the finger. Stop means are provided by fixed outboard finger elements, juxtaposed opposite movable finger elements, for providing improved stability for positioning the comparison gage.

Abstract: The present invention is directed to a method and device for determining the location of a cutting tool with respect to the rotational axis of a spindle-mounted workpiece. A vacuum cup supporting a machinable sacrifical pin is secured to the workpiece at a location where the pin will project along and encompass the rotational axis of the workpiece. The pin is then machined into a cylinder. The position of the surface of the cutting tool contacting the machine cylinder is spaced from the rotational aixs of the workpiece a distance equal to the radius of the cylinder.

Abstract: An LVDT displacement transducer and a probe actuation arrangement integrated into a probe assembly. The probe assembly includes a tubular housing within which is mounted at one end an LVDT and within the other the probe actuation arrangement. In the preferred embodiment, an air pressure actuator arrangement is utilized and comprises a stepped diameter probe extension shaft having a smaller diameter section joined to the LVDT core element, and extending through a bulkhead bushing into a pressure chamber, the larger diameter section of the shaft passing out through the opposite end of the housing and serving to mount the probe sensor contact. The differential diameter of the stepped probe extension shaft is subjected to air pressure via an air fitting communicating with the air chamber and which acts against a return spring to enable self actuation of the probe extension shaft and attached core element.

Abstract: A configured contour measuring apparatus comprising: a table movably provided on a bed; a driving mechanism for moving said table; first detecting mechanisms for detecting a value of movement of said table relative to the bed as a digital signal; a mount base provided on said table and made movable in a direction perpendicular to movement of said table; a detecting head secured to a column erected on said bed; a sliding shaft slidably provided on said detecting head and having a stylus at the lower end thereof in opposed relationship with said mount base; a balancer weight connected through a hanging line to said sliding shaft and made slightly lighter in weight than said sliding shaft; pulleys for supporting the intermediate portion of said hanging line; and second detecting mechanisms for detecting a value of movement of said sliding shaft as a digital signal.

Abstract: An inspection apparatus for determining the contours of sheet material, particularly glass sheets, comprising a checking fixture having a plurality of probe assemblies for determining the exact position of points along the sheet and the deviation, if any, of such measured points from reference points constituting the ideal contour. The probe assemblies generate linear signals transmitted to a controller which, in turn, converts such signals into data displayed on a video screen in selectively different forms.

Abstract: A cylindrical blank is mounted on the turn table of a vertical lathe with the axis of the former as close as possible to the axis of the latter. The angle between a reference point on the periphery of the blank and a measuring point circumferentially displaced from the reference point and the deviation of the periphery at the measuring point from a circle about the axis of the turn table are measured. Then an axis at which the dispersion of the deviation at the measuring point is a minimum is calculated by using the measured angles and the deviations to determine the distance between the axis of the blank and the axis of the turn table, and press members mounted on the turn table are actuated to move the blank by the distance thus determined to coincide the axis of the blank with the axis of the turn table.

Abstract: A rotary mounting for supporting a workpiece for rotation has a number of support members which are small in relation to the workpiece and each of which forms an aerostatic bearing with a flat surface of a table. The support members are connected by respective links to a radial bearing connected to the table and supporting the mounting for rotation.

Abstract: A coordinate measuring machine (10) having a vertically mounted probe (32), the weight of which is offset by an air counterbalance system (100). The air counterbalance system is adapted to use a source of air under pressure acting upon a piston (127) coupled to the vertically mounted probe (42). A torque converter (130) is mounted between the probe (42) and the piston (127) allowing the piston (127) to have a shorter travel than the allowable vertical travel of the probe (42). The air counterbalance system (100) preferably has components selected and arranged to minimize friction and weight to avoid distorting the precision of measurements on the coordinate measurement machine.

Abstract: Apparatus suitable for inspecting the positional accuracy of a hole or passage in a workpiece comprising workpiece support means and a probe assembly. The probe assembly comprises two parallel tubes; one provided with a thermistor bead maintained at a temperature higher than ambient and the other provided with a nozzle adapted so as to direct a jet of air on to the thermistor bead. The tubes are positioned on each side of a workpiece to be inspected so that as the tubes are traversed across the workpiece, the jet of air is prevented from impinging upon the thermistor bead. However when a hole or passage in the workpiece is spanned by the nozzle and thermistor bead, the air jet will impinge upon the thermistor bead, thereby cooling it and hence providing a signal that a hole or passage has been encountered.

Abstract: An improved gauge assembly is utilized to measure the size of a workpiece during a grinding operation. The gauge assembly includes upper and lower gauge members which are movable under the influence of a pair of fluid motors. When the gauge assembly is in an open condition, the upper gauge member is held in a raised position by a relatively high fluid pressure supplied to the motor associated with the upper gauge member. At the same time a relatively low fluid pressure is supplied to the fluid motor associated with the lower gauge member so that it remains in a lowered position. When the gauge assembly is to be utilized to measure a workpiece, the fluid pressure in the motor for the upper gauge member is decreased to enable the upper gauge member to move downwardly into engagement with the workpiece. At the same time, the fluid pressure in the motor for the lower gauge member is increased to raise the lower gauge member upwardly into engagement with the workpiece.

Abstract: The invention contemplates an improved work-contacting probe for use in a measuring machine wherein the relationship between contacted locations on a workpiece are reduced to coordinate digital data. The various described probe embodiments feature means whereby positional errors due to probe flexure upon work contact are substantially reduced, as compared to pre-existing structures.

Abstract: Apparatus for measuring the wear of a shaft bearing includes a source of fluid, a valve, and a linear transducer. The transducer has a probe which may be urged aganst the shaft by admitting fluid from the source to a chamber in the transducer. As the probe is urged against the shaft, voltages provided by the transducer change in a relationship to the movement of the probe. The voltage change is monitored to measure the shaft bearing wear. Upon completion, the fluid is vented, which allows the probe to return to a rest position.

Abstract: The present invention relates to coordinate measuring machines which are used for determining the location of a point in the X, Y and Z axes in order to permit inspection, checking, or performing other operations on work pieces. The measuring machine includes a probe for engaging the work piece and providing position information of points on the work piece. The probe is mounted on a cantilever arm that is supported on two parallel dual granite ways or rails through air film bearings. The probe is counterbalanced in a unique manner with an air cylinder and is also mounted on air bearings on its cantilevered support arm, and the probe may be rotated 360.degree. for maximum flexibility and ease of operation.

Abstract: This invention relates to a height gage of a type to be attached to a digital readout and in which a source of air under pressure is utilized for providing anti-friction means for moving a slide which carries a tool for measuring distance.

Abstract: An auxiliary air bearing system (50) for reducing friction in mechanical bearings (41, 42) to improve repeatability of measurements on a coordinate measuring machine (10). The air bearing system (50) and mechanical bearings (41, 42, 43) support a moveable carriage (30) on a base (20). The air bearing system (50) comprises an air pad assembly (70) mounted to the carriage (30), an air system (80) supplying air under pressure and a rail system (60) mounted to the base (20) with the air pad (70) including a compressed spring (76) captivated therein. Air under pressure is directed between the air pad assembly (70) and the rail system (60), causing the air pad assembly (70) to lift from the rail system (60) and the base (20). The air bearing system (50) and the spring (76) reduce the effect of any irregularities on the rail that would otherwise cause measurement errors.