ARB,
I don't know which "Black" units you are referring to as the extremely early units were black but quite different from the black units designated as HRT7, HRT9 , HRT11 and S5C.
The first rotary tables were adaptations of manual rotary tables and had a stepper motor "hanging" off the side of the table. This applies as well for the first 5c units.
The next generation of tables, (and 5c units too), had their servos enclosed in sealed covers. A cast unit for the 5c and a sheet metal one for the rotary tables. These were from about 1990 to 1994 or so. these are the HRT 7,9,11. And the S5C (5c indexer) would be from this time frame.
Nothing wrong with the HRT 7,9,11 series of equipment. Or S5C for that matter. Good servos and well designed enclosure. Good air brake and drive system. Very close to present day systems. And as you would expect the HRT7 was a 7" table. HRT9 a 9" and HRT11 a 11".
Just a note: there was also a H5C indexer that was a "stepper" motor driven indexer. Not to be confused with the HA5C which is the present day indexer with a servo drive.
Next came the HRT metric series.HRT160, HRT210,HRT310,HRT450 and HRT600. A HRT160 was 160mm table or 6.30 for imperial.
These units were red in color. And this series showed up in about 1995 until 2000.
In 2000 the units then started to be shipped as white in color. And are basically the same design as the red units.
This is just a very short and sweet explanation of the most common tables. As there are many more tables and indexers. Brushless, tilting, dual head, four head,ETC.
And there are 14 pin and 17 pin cables and on and on......
Oh and as far as speed..the HRT series, both 7,9,11 and Metric, all index between 60 and 80 degrees a second max. Depends on the size. That is for the standard models as they have high speed ones too.
Hope that helps some. If you need more or have specifics let me know and I'll try and help.
I also stand corrected on any of the above as my old mind has forgot a lot as of late.
