Capstans are also found in the mechanisms of tape recorders, where they have a similar function - they apply force to the tape causing it to be drawn off the spool, past the heads, and onto the take-up spool. Such capstans are precision-machined spindles, with a very accurate surface profile - any out-of-roundness or imperfections cause an audible effect called "flutter". The tape is held against the capstan by a rubber wheel called the pinch wheel or pinch roller.
The capstan is analogous to a rack and pinion arrangement found in gear systems.