What makes the Air Bearing LVDT Different from Spring Based Indicators?

Why is it possible to obtain much higher accuracy measurement performance from the Air Bearing LVDT?

Radial Stiffness The LVDT stylus shaft rides on a thin air film at 60 psi. The radial stiffness of the probe stylus is generally 1 microinch of side deflection per one gram of side load. At very light stylus forces (1/10 gram), the side loading of the probe is very minimal. Spring based indicators have little radial stiffness and deflect to the side when loaded radially. With the Colorado Precision Air Bearing LVDT, measurements where the part contacts the side of the probe stylus ball are possible due to controlled radial stiffness.

Constant Stylus Force over the Measurement Range The stylus force on the Colorado Precision Air Bearing LVDT is controlled by air pressure as opposed to a spring. Consequently, there is no variation in stylus force over the entire motion range of the stylus shaft as there is with spring type indicators..

Adjustable stylus force to very light contact forces (1/10 gram) On the Colorado Precision Air Bearing LVDT, the stylus force is adjusted by a needle valve on the back of the probe body. As the needle valve is opened, a difference in air pressure between the front of the stylus and the back of the stylus is obtained. This differential in air pressure is used to control the forward stylus force to very light contact forces.

Specially designed LVDT Amplifier for use with the Colorado Precision Air Bearing LVDT Low electronic noise in the amplifier signal (low noise to signal ratio) enables high resolution over relatively large ranges (1 microinch resolution over +- .020 inch range). The same feature of low noise to signal ratio enables the extremely high resolution measurement capability over small ranges (.05 microinch resolution over a +- 20 microinch range).

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