Capstan
Nautical capstan
A capstan is a rotating machine used to control or apply force to another element, usually linear. The term was first used for the capstan on a ship, which is used to control ropes that are wound around it. The rope is wound around one or more times, but is not stored on a capstan – that arrangement is usually called a winch. Ships' capstans were traditionally manually operated – consisting of a shaped wooden drum with handles inserted into the rim, at which men could push or pull. Modern capstans are powered electrically.
| Breakdown of a sailing ship | |
|---|---|
| Parts of a sailing ship | |
| Anchor | Bilgeboard | Capstan | Centreboard | Daggerboard | Deck | Figurehead | Forecastle | Gunwale | Hull | Jackline | Leeboard | Mast | Poop deck | Rudder | Ship's wheel | Stern | Tiller | Winch
| |
Tape recorder capstan
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 at a precise, constant speed. 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. Dual capstan – one on each site of the heads – assists in more linear tape travel across the heads and results in less variances in the recorded/playback signal.
Gear systems
The capstan is analogous to a rack and pinion arrangement found in gear systems.