I think the Ampex cart machine was the ACR25. If memory serves it did use vacuum to help in tape handling. It also used a vacuum guide for proper headwheel contact with the tape. The vacuum, and the curved shape of the guide, would hold the tape in proper contact with the rotating headwheel.
Ahh the good old days. I wonder if anyone ever got their tie caught in one of these things ......... and lived to tell the tale.
