A winch uses a set of gears to provide mechanical advantage to move a person or load. A winch allows a single person to easily move a load many times heavier than they would be able to simply by pulling on a rope or cable directly.
Winches fall into two main categories. A traditional winch, such as used on an off-road vehicle, uses a drum with a cable or rope wrapped around it. As the drum turns, the cable is either unspooled or spooled onto the drum. Another type of winch is a capstan. A capstan does not store the rope around a drum. Instead, the rope wraps around the drum to provide friction to pull the rope but the rope then exits the capstan. A traditional winch usually uses a metal cable, or in the case of some applications, a rope made of dyneema or other modern fiber. Capstan winches in contrast usually use rope.
Both types of winches have advantages and disadvantages. Since a traditional winch keeps the cable stored on the drum, this allows the winch to be kept as a single unit ready for use. Since the rope on a capstan is not stored on the drum it is kept as a separate item. The rope must be attached to the capstan to use it.
For frequent use, capstan winches have a number advantages. A major advantage to a capstan winch is the rope is midline attachable. A rope can be wound around the capstan at any point along it’s length without having to start at the end of the rope.
If the cable on a traditional winch is kinked, it must be replaced. In a work environment this causes work to stop while the entire cable is unwound from the winch and a new cable is wound onto it. This is assuming that a replacement cable is readily available. Since capstans use rope, there is less chance of unintentional damage. Since the rope on a capstan isn’t kept spooled around the drum, the line can easily be replaced if damaged. If the rope is damaged, the old rope can simple be taken off of the capstan midline and replaced with another rope.
Since capstan winches allow easy switching of ropes it makes them ideal for situations where multiple workers or loads must be moved. In the case of confined space work, each worker can have a separate rope attached and the ropes can be raised or lowered as needed without having to detach the end of the rope from the worker. This allows the rope to act as a backup safety line to very quickly retrieve an injured worker.
Capstan winches such as those made by Harken offer various features depending on the needs of the user. They can be used with suitable ropes of various diameters made from a range of materials without the need to buy a specialty rope. Although a capstan winch is more expensive than a traditional winch, this allows for lower total cost of ownership.
For more information on capstan winches contact us.