A fairlead is a device used to guide a cable, rope or chain and prevent catching or fraying. It can be nothing more than a hole in a plate of steel or wood or it can be as complex as a roller unit. The fairlead allows the cable or rope to be pulled in a direction that is not straight away from the line. The line is pulled onto a spool straight from the fairlead while it enters the fairlead at an angle.
While fairleads are mostly found on sailing ships and heavy construction equipment, a commonly used version is found on small vehicle winches. Usually the roller type, this fairlead allows the winch cable to operate easily and smoothly as the line is spooled back onto the winch. By operating with less resistance, the winch is able to operate longer without over heating and draws less amperage from the battery.
On a sailing ship, the device helps to raise and lower the sails in a smooth manner. The rope is pulled horizontally by the crew while it hoists the sail vertically. By passing the rope through a hole in a block of wood mounted on the ship's deck, the crew is better able to put their strength to use and raise the heavy sail. The fairlead also helps to keep the deck orderly and arranged.
Fairleads have been in use since the time of the Roman Empire. Ropes that cocked great catapults were passed through fairleads and wound onto spools. The holes could be lubricated with animal fat or petroleum products to not only wind easier but to unwind and fire faster as well. Catapults were not the machines that used fairleads; draw bridges also utilized them for strength and raising and lowering assistance.
A simply designed device that has found itself useful for centuries, the fairlead has been used in almost all cultures and civilizations. From braking systems on Conestoga wagons in the American West to the bell towers of Notre Dame, fairleads have been assisting ropes and cables in pulling and preventing fraying for centuries.
By placing a smooth edge against the line, it is permitted to pass freely through the opening without causing damage. By installing an actual roller device for the line to come into contact with, the line is allowed to work with virtually no added resistance. Wetting or lubricating the line as it passes through the hole will prevent heat from damaging the line and causing fraying to begin.