Crane Works Magazine (March-April 1996 Issue)
Wire rope corrosion and wear can be difficult to control, making continual lubrication essential to extending wire rope life. However, lubricating with the aid of brushes, rags, gloves or by other means can be costly and ineffective. Surface application may form a film that water vapor can penetrate. The water becomes trapped inside. As temperatures change, rust forms. With a sprayer often just the exterior of the wire rope even becomes coated, and not the core. High pressure lubrication systems, though, make the process of extending rope life more efficient and effective.
Although specific details may vary by company, lubrication systems usually work in several steps during one application. The wire rope’s surface is scraped and its grooves cleaned of product build-up, rust and any foreign objects as it enters a chamber. Then pressure forces out moisture trapped in the internal strands and replaces it with the new lubricant.
This entire process requires very little equipment. The wire rope is placed in a lubricating chamber, and the two halves of the chamber are clamped in place. The unit is coupled to a high- pressure lubricating pump by a flexible hose, which forces the lubricant into the chamber. Some systems use a dual hose system. One hose carries compressed air to the chamber to provide the high pressure needed to clean the wire rope, while the other carries the lubricant. Other systems us a single hose to carry both the compressed air and lubricant. Manufacturers of lubrication systems provide the user with recommended air pressure settings for various wire rope travel speeds. The unit is anchored by two chains to a stationary object and the pump is started, enabling the wire rope to be pulled through the lubricating chamber and wrapped around a winch. It is then ready for lifting procedures.
The system takes only one to two people to operate. Set-up time s minimal and can be done by the user. The time it takes to lubricate a wire rope depends on its size, length and the lubricant viscosity. One example is a job done by the Kirkpatrick Group. It completed lubrication of a 7/8″ non-spin load line (1,200 feet) and 7/8″ right regular lay jib line (500 feet) on a 150-ton crawler crane with a low viscosity lubricant in about 30 minutes.
Pressure lubrication is most effective when used on ropes in good condition as a preventative maintenance operation. Tests at Bridon Ropes have demonstrated that well lubricated ropes will have a fatigue life up to 300 percent longer than dry ropes.