| 摘要 |
A sidereal-rate drive assembly for an astronomical telescope which includes a worm gear for rotating the telescope about its polar axis and which is engaged by a motor driven worm. The worm gear fits over the end of a polar shaft, and it and the end of the polar housing are grooved to form ball bearing races. A plurality of balls are placed in the races to constitute a ball bearing so that the worm gear may be freely rotatable on the polar housing about the polar axis. The telescope mount includes a polar shaft which extends through the worm gear into the polar housing along the polar axis. The worm gear is frictionally coupled to the polar shaft through a sleeve composed of nylon or other appropriate material, and through a fiber washer, or the like. The weight of the telescope provides a desired friction force to enable the worm gear to turn the telescope mount about the polar axis. However, the telescope mount may be turned by hand relative to the worm gear about the polar axis to be set to any desired angular position.
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