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Amateur astronomers accustomed to fork mounts or Dobsonians often have trouble visualizing the movement and orientation a German equatorial mount (GEM) exhibits as it tracks across the sky. The photos on this page might help. They show a telescope on a Losmandy G-11 mount viewed from the north looking south. I've added red arrows to show the movement direction at various points.
Here the telescope is looking to the east at declination 0. The telescope is horizontal, the counterweight shaft is pointing downward, and the whole assembly is rotating slowly clockwise as the mount's RA axis tracks westward. As this rotation continues, the telescope "falls backward" on the west side of the mount, still looking eastward.
From the due-east position shown above, the telescope has tracked a target almost to the meridian, due south. The telescope has "fallen backward" to the west side of the mount (still looking slightly east of south), and the counterweight shaft is horizontal on the east side.
As the arrow at the bottom of the photo shows, if telescope were pointing higher in the sky (it's at declination 0) further rotation would cause the camera equipment hanging off the rear to collide with the concrete pier. At or near this point, a German Equatorial mount requires the user to initiate a "meridian flip" to swap the position of the telescope and the counterweight so the mount can point at the same target and continue to track it westward.
When performing this flip, it's important to maintain an east-heavy weight bias, so the mount's RA drive worm pushes the worm gear against gravity (as opposed to allowing gravity to "pull" the worm gear teeth against the worm) This eliminates gear lash and provides more accurate tracking. In this photo, the counterweight is on the east side of the mount so the weights are positioned toward the end of the shaft. Compare the orientation of the counterweight shaft in this photo with its orientation after the flip two photos down, and read the accompanying comments there.
During the meridian flip, the RA axis rotates counter-clockwise, and the telescope swings through north. Here the counterweight is traveling upward on the west side, the scope has just passed north, and is "falling backward" on the east side of the mount.
After the meridian flip, the telescope is once again pointing due south at the same target as it was before the flip (we're assuming the target has transited the meridian while the mount was performing the flip). But now the telescope and counterweight have exchanged positions.
Notice that after the flip the telescope is on the east side of the mount and the counterweight is on the west side. In order to maintain the east-heavy weight bias discussed above, the counterweights should be repositioned closer to the mount, reducing the weight on the west side. Repositioning the weight is an unwelcome task, because it requires manual intervention, and can't be done from a remote location. I have eliminated this task with the installation of this constant-bias counterweight system which uses a weight suspended from the RA hub.
As the arrows in this photo indicate, the mount continues to track westward (rotate clockwise) on the RA axis, with the telescope out of danger of hitting anything beneath the mount. As the rotation continues, the telescope ramains on the east side of the mount, looking westward.
Tracking continues from the position shown above until finally we reach this position, where the telescope is looking due west at declination 0. The telescope is once again horizontal, and the counterweight shaft is pointing downward. Continued clockwise rotation from this point won't hurt anything, but the telescope then would be pointing below the horizon (or, by increasing the declination, would be looking northward).
Most mounts have provisiones to define a "Park" position. This is my G-11's Park position. It was carefully chosen to ensure that all parts of the telescope are well below the roof structure when it is rolled closed. Conveniently, the Park position also aims the telescope at a flat-field light box so it's ready to expose flats as soon as the mount is parked.
