On 8/22/2015 5:32 AM, Brent Hilpert wrote: > On 2015-Aug-21, at 10:20 PM, Ali wrote: > > A brief conceptual overview: > > Vacuum-column and spring-arm drives comprise 3 servo systems: > - each reel motor is in a closed servo loop with position sensors in > its associated vacuum column or spring arm. > - the capstan motor, driving the exposed tape between the reels, is in > a servo loop with a tape-speed sensor, > and externally controlled by commands for forward/reverse and speed > selection. > > The 3 servo systems are electrically independent (in control terms and > leaving aside power supplies). > The connection between them is the tape. >
One other type: spring arm, where the tape reels do all the tape moving, and a speed sensor, rather than a traditional capstan. The tension arm is part of the servo system to which the reel motors respond. In this case the reel motors and tension arm are anything but independent. Example: HP 88780 JRJ
