Gyroscopes are used to detect and determine traveling position and angular velocity in airplanes and ships. Gyros are structurally divided into two groups depending on the number of directions and speeds of movement to be detected: those with one degree of freedom and those with two degrees of freedom.
The performance of a gyro depends on the characteristics of the bearing. Thus, a gyro bearing is required to demonstrate top grade performance among the ultra-precision miniature bearings. Gyros have two sets of bearings. One set supports the rotor shaft running at high speed and the other set supports the frame (gimbal). Both must have stable, low frictional torque. Principal types and application environments of rolling bearings for gyros are shown below. 1. Rotor: Bearing type: Angular contact ball bearing Running conditions: 12000, 24000 min−1 or 36000 min−1,60 to 80°C ,helium gas
The rotor bearing is required to offer extremely-low, torque at high speed, and free from variation and long term stability. To meet these demands, the bearing uses an oil immersed cage in most cases. A lubrication method of injecting the lubricating oil dissolved with solvent into a bearing is also available, but this method requires adequate concentration adjustment because the frictional torque is affected by the oil amount . In such an event, the oil amount is adjusted through centrifugal separation to obtain variation-free running torque. A special bearing type, in which an end cap is integrated with the outer ring, may also be used.
2.Gimbal:
Bearing type: Deep groove ball bearing Running conditions: Oscillation within ±2°,Normal temperatures to 80°C,Silicon oil or air
Requirements on the gimbal bearing as a gyro output axis include low frictional torque and vibration resistance. Select the maximum starting frictional torque for typical bearings. Much smaller starting torque can be obtained through precision machining of the raceway groove and special design of the cage.
