Tsubaki KabelSchlepp’s RSC System Solves Cable Management Needs for Port Cranes
Cable management is an increasingly important issue for cranes operating in seaports. Traditionally, methods of cable management on port cranes has been handled with festoon systems or standard cable carriers. On seaports, ship-to-shore cranes, rail-mounted gantries, or rubber-tire gantries travel at extreme lengths and speeds, pushing traditional cable management methods to their design limits.
To address these concerns, Tsubaki KabelSchlepp developed the next evolution in cable carriers with the Roller Supported Chain (RSC) system. The RSC system has been specifically designed to solve cable management needs within the port crane industry.
The RSC System
The RSC system resolves the shortcomings of traditional cable management methods on port cranes. For example, having the wheels as part of the link construction can cause excessive vibration and jams, which will lead to accelerated wear and eventually total replacement of the cable carrier. The RSC system was designed so that no rollers are built into the cable carrier, and the upper run of the cable carrier never comes in contact with the lower run of the cable carrier.
It also uses maintenance-free ball bearing rollers that are mounted to the side of the cable carrier. The rollers are fully exposed and roll on the smooth top surface of the guide channel. With this design, no bounce or vibration is caused by the wheels rolling on top of each other. Not only does this ensure low noise and vibration during operation, but it also reduces the tow forces by 90% when compared to traditional cable carrier systems—and even more than on festoon systems. The reduction in tow force minimizes the wear on the cable carrier, which greatly increases its life.
The design also ensures that all components on the RSC system are easily accessible. Recesses in the guide channel make it easy to reach the rollers and modular side parts. This allows for easy inspection of the rollers without lifting or touching the cable carrier. Worn rollers can be replaced individually during maintenance, if necessary. This means that the time-consuming and expensive replacement of the complete cable carrier is no longer necessary if the wheels wear out.
Special Guide Channels
Another feature of this RSC system is the specially designed guide channels, which can be mounted together regardless of the defined support distances on the crane. Compared to the usual fixed support distance of 2 meters, the RSC system saves connection points, and therefore steel components, for the support structure. The RSC solution can operate at speeds and distances that have not been obtainable with traditional cable management methods. It can easily operate at speeds in excess of 10 meters per second over a travel distance of 300 meters, carrying a load of 100 lbs. per foot.
RSC vs. Festoon
Compared to festoon systems, the RSC cable carrier addresses several concerns beyond crane operating speed. With a standard festoon system, each cable needs to be approximately 115% of the length of crane travel. With the RSC cable carrier system, each cable only needs to be approximately 52% of the length of travel. On a long-travel port crane system, this reduction in required cable length can translate into a substantial cost savings.
The RSC cable carrier system also requires a much smaller operating envelope than a festoon system. A typical, long-travel festoon system can require an operating envelope space as large as 15 feet in height and 5 feet in width. An equivalent long travel RSC cable carrier system may only need an operating envelope of 3 feet in height and 2 feet in width.
Even more important to crane operators is the “parking station” that a festoon system requires. A long-travel festoon system on a crane often needs up to 10% of the total travel distance for the parking station. On a ship-to-shore crane, this parking station requirement for the festoon system could easily be in excess of 60 feet. By comparison, an RSC cable carrier system virtually eliminates this requirement, and on an equivalent system, it would require less than 5 feet of parking space.
Another key feature of the RSC cable carrier system is the amount of support it provides the cables. In an RSC cable carrier system, the cables are laying horizontally, fully supported, and separated inside the cable carrier. A festoon system’s cables are only supported periodically at the saddles, with the cables left hanging unsupported once the system goes beyond the saddles. Not only does this hanging increase the stress on the cables, but it also exposes the cable to constant motion from the wind and other outside forces.
Maintenance of cables on an RSC cable carrier system is also much easier. Replacing a cable on a festoon system will require you to manually release it from each festoon saddle location and then install the new cable. Not only will this increase labor, but the new cable will need to be more than twice as long as what the RSC system would require. The RSC system offers quick installation by just pulling the new cable through the carrier, and then strain relieving the cable at each end.
About the Organization
U.S. Tsubaki is a subsidiary of Tsubakimoto Chain Co., a leading manufacturer and supplier of power transmission and motion control products and is the world's market share leader in roller chain. Tsubaki provides optimal and customizable solutions for a range of applications within the Port Crane Industry. These include Cable & Hose Carriers and Cables, Roller Supported Chain Systems, Drive Chains, Leaf Chains, Backstops & Clutches and Electric Actuators. With nearly a century of successful manufacturing know-how and technical expertise, Tsubaki can provide the best engineered solution to fit your specific needs, and provide the Tsubaki Advantage. Tsubaki is an ISO 9001:2000 and ISO 14000 
registered company.
