SPIN BALANCE MACHINES (continued)

Hydraulic vs. Gas Bearings Space Electronics machines use an air bearing in place of a hydrostatic oil bearing. This has the advantage that only one bearing is necessary for both MOI and POI measurement. Furthermore, gas bearings are inherently superior to hydraulic bearings. A gas bearing has less bearing noise than any other kind of bearing, is less susceptible to damage from a dirty environment (since the bearing is continuously purged with clean air), and can be made with smaller runout than any other type of bearing.

There have been explosions which resulted from a leak in a high pressure hydraulic line. Under the right conditions, the oil mist ignites spontaneously. Recently, the US Government made the decision to replace a number of test machines which use hydrostatic oil bearings because of this danger. Our machines do not use high pressure oil and do not have this safety problem.

Both oil and gas bearings can be damaged if the pressure is lost while the bearing is spinning. For our air bearing, we solve this problem by providing a reserve air tank which supplies lubricating air to the bearing during emergency shutdown. A pressure sensor automatically switches to this backup supply if the normal air supply pressure is lost, so there is ample time to smoothly decelerate the payload. Since oil is incompressible, it is not possible to provide this type of protection with a hydrostatic oil bearing.

Calibration rotor and weights provided A proving rotor and a set of precision weights are supplied to calibrate and verify the performance of the spin balance measurement. A certified calibration beam and weights are supplied to calibrate the moment of inertia measurement feature of the machine. All values are certified traceable to NIST. A proving rotor and a set of precision weights are supplied to calibrate and verify the performance of the spin balance measurement. A certified calibration beam and weights are supplied to calibrate the moment of inertia measurement feature of the machine. All values are certified traceable to NIST.

On-line computer A computer is supplied with each instrument. The software guides the operator through the procedure for each measurement or calibration sequence, so that the operator rarely needs to refer to the instruction manual.

L Adapter fixture for horizontal payload orientation
Selecting Instrument Size

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SAWE Paper:                       A New Spin Balance Machine