Abstract: A precision drive assembly for producing constant accurate angular motion of an instrumentality about an axis and which includes a lead screw and a nut threaded to the lead screw. The lead screw is driven by a motor. A radial (tangent) arm is coupled in one end to the nut and at the other end to the instrumentality so that linear movement of the nut along the lead screw causes the radial arm to turn the instrumentality about its axis. Position-rate errors inherent in the drive assembly are corrected by mechanical cam means, or by electric/electronic drive means motor.

Abstract: 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.

Abstract: An extremely accurate and inexpensive true sidereal rate drive assembly for an astronomical telescope, the telescope including a base having a driven gear rotatable about the polar axis of the telescope, and the drive assembly including a housing mounted on one side of the base, a single low speed synchronous drive motor mounted in the housing, and a worm gear mounted on the drive shaft of the motor for directly coupling the motor to the driven gear. In addition, a thumbwheel may be provided which is coupled to the motor shaft through appropriate reduction gearing, and which serves as a fine adjustment control for the telescope.

Abstract: A precision equatorial mounting unit and drive system for an astronomical telescope is provided which is constructed so that the mounting, per se, is modular and may be easily and quickly converted to a German equatorial platform for mounting different sizes and types of telescopes, or to a fork mount likewise for different sizes and types of telescopes. The drive system includes a worm gear sector drive to provide a highly accurate sidereal tracking system in a minimum of space. The mounting unit includes a built-in adjustable timer with a calibrated scale, and an automatic cut-off; the unit also includes a precision latitude adjustment and associated plumb bob scale which may be calibrated directly in latitude.