The weight driven clock drives were available in two different sizes for the 4″, 5″ and 6″ Polarex and Unitron scopes: one size for the 4″ and 5″, and a larger size for the 6 ” scopes. According to the catalogs, with the weight driven clock drive, the telescope operates independent of the source of electricity with the speed of the drive maintained at a constant rate by means of a spinning governor rotating within ball bearing supports.
The clockwork is protected by a chromed brass and plexiglas outer case. It is equipped with a variable speed control to obtain the required rate for following the stars, the sun, or moon.
Some comparison photos of the two versions of the weight driven clock drive (courtesy of Stephen Brennan):
The following photos of the 4/5 inch version were provided courtesy of Chuck Mitchell:
The following photos of the 6 inch version were provided courtesy of Stephen Brennan: