A portion of a model depicting a manual capstan in use. The sailors would coordinate the rhythm of their movements by singing a particular type of
sea shanty as they walked around the capstan.
A
capstan is a rotating machine used to apply
force to ropes, cables, and hawsers, commonly, though not exclusively, in a maritime setting.
History
The word, connected with the
Old French capestan or
cabestan(t), from Old Provençal
cabestan, from capestre "pulley cord,", from Latin
capistrum, -a halter, from
capere, to take hold of, seems to have come into English (14th century) from French or Spanish shipmen at the time of the Crusades. The conjecture that it came from the Spanish
cabra, goat, and
estanto, standing, is untenable.
Early form
A capstan on a sailing ship. The upper portion operates the anchor windlass below in the
ForecastleIn its earliest form, the capstan consisted of a timber mounted vertically through a vessel's structure which was free to rotate. Levers, known as bars, were inserted through holes at the top of the timber and used to turn the capstan. A rope wrapped several turns around the drum was thus hauled upon. A rudimentary
ratchet was provided to hold the tension. The ropes were always wound in a clockwise direction (seen from above).
Later form
Capstans evolved to consist of a wooden drum or barrel mounted on an iron axle. Two barrels on a common axle were used frequently to allow men on two decks to apply force to the bars. Later capstans were made entirely of iron, with gearing in the head providing a mechanical advantage when the bars were pushed counterclockwise. One form of capstan was connected by a shaft and gears to an anchor windlass on the deck below.
Modern form
Modern capstans are powered electrically,
hydraulically,
pneumatically, or via an
internal combustion engine. Typically, a
gearbox is used which trades reduced speed, relative to the
prime mover, for increased
torque.
Similar machines
A capstan differs from a
windlass, which is used for similar purposes, in having the axis on which the rope is wound vertical instead of horizontal. In
yachting terminology, winches function on the same principle as capstans, though in industrial applications, the term
winch generally implies a machine which stores the rope on a drum.
Use on land
Hydraulically-powered capstans were sometimes used in
railway goods yards for
shunting, or shifting railcars short distances. One example was
Broad Street goods station in
London. The yard was on a deck above some warehouses, and the deck was not strong enough to carry a locomotive, so ropes and capstans were used instead.
