Winch

Modern self-tailing winch on a sailing boat. Here, the line winched is a jib or spinnaker sheet which runs from the sail (upper left, not shown) to a block (lower right,not shown) and from there to the lower part of the winch. The handle is detachable to facilitate handling of the line.

A winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise adjust the "tension" of a rope or wire rope (also called "cable" or "wire cable"). In its simplest form it consists of a spool and attached hand crank. In larger forms, winches stand at the heart of machines as diverse as tow trucks, steam shovels and elevators. The spool can also be called the winch drum. More elaborate designs have gear assemblies and can be powered by electric, hydraulic, pneumatic or internal combustion drives. Some may include a solenoid brake and/or a mechanical brake or ratchet and pawl device that prevents it from unwinding unless the pawl is retracted.

Applications

Anchor winch of the polar research vessel Polarstern

Besides industrial applications (e.g. in cranes), winches are used for towing cars, boats, or gliders. There are several winches on almost every boat or ship where they are used to pull anchor or mooring lines, halyards, and sheets.

The rope is usually stored on the winch, but a similar machine that does not store the rope is called a capstan. When trimming a line on a sailboat, the crew member turns the winch handle with one hand, while tailing (pulling on the loose tail end) with the other to maintain tension on the turns. Some winches have a "stripper" or cleat to maintain tension. These are known as "self-tailing" winches .

Winches are frequently used as elements of backstage mechanics to move scenery in large theatrical productions. Winches are often embedded in the stage floor and used to move large set pieces on and off.

Winches have recently been fabricated specifically for water and snow sports (e.g. wakeboarding,wakeskating, snowboarding, etc.). This new generation of winches are designed to pull riders swiftly across a body of water or snow by simulating a riding experience that is normally supplied by a boat, wave runner, or snow mobile.

Example of winch designed for wakeboarding. These winches consist of a small four-cycle gasoline engine, clutch, and spool all housed inside of a steel frame. A rider is towed rapidly toward the winch as the rope winds around the spool.

Tirfors

Tirfors also commonly known as griphoists are winches that instead of using spools to move rope or wire through the winch use self-gripping jaws. Powered by moving a handle back and forth they allow one person to move objects several tons in weight.

History

The earliest literary reference to a winch can be found in the account of Herodotus of Halicarnassus on the Persian Wars (Histories 7.36), where he describes how wooden winches were used to tighten the cables for a pontoon bridge across the Hellespont in 480 B.C. Winches may have been employed even earlier in Assyria. By the 4th century BC, winch and pulley hoists were regarded by Aristotle as common for architectural use (Mech. 18; 853b10-13).

The largest electric drive winch in the world is placed on the Balder, a construction ship. It is used as a mooring line deployment winch with a diameter of 10.5 meters and a safe working load of 275 metric tonnes.

See also

• Pulley
• Steam donkey
• Article about boat winches