Stromag brakes fitted to powerful shipyard shiplifts
Life out at sea is tough, which drives demand for shipbuilding and repair of existing vessels. Since the dawn of large-scale shipbuilding and repair, a principle challenge has been moving ships from sea to land and vice versa; making shiplifts a crucial part of any modern shipyard. Working under huge loads, it’s important that key assemblies such as brakes are up to the task.
An Italian winch and gearbox manufacturer providing assemblies for a shiplift system approached Stromag to provide 4BZFM brakes that could deliver reliable stopping power for the system’s hoists.
Shipbuilding and repair
As of 2018, the global shipbuilding market was worth a staggering $114.3 billion US1 with 281 active shipyards operating worldwide2. Over 50,000 merchant ships form the spine of the international trade network3 while the world’s 10 largest navies have an estimated 4,185 vessels in active service4. What both merchant and naval fleets share in common is the need for expansion and repairs. Consequently, shipyards are important facilities.
Ship out of water
Most modern shipyards utilise immensely powerful shiplifts, which can raise and lower huge vessels in a controlled manner.
A shiplift works by positioning a platform underneath the ship, which is then raised or lowered by multiple hoists in synchronicity. This allows horizontal or angled (if ballast is a factor) lifting of the ship, ideal for launching or dry-docking vessels. Consequently, the vessel can be released out to sea or moved to an onshore transfer system for maintenance work in a highly streamlined manner. This contributes to a reduced time for repair, which benefits the shipyard in terms of efficiency and reputation.
Lifting a load as large as a ship requires a mix of precision, power and reliability. Any loss of synchronicity risks the ship tipping, so power transmission equipment must move the huge load in a highly controlled manner. Furthermore, in conditions such as a loss of power, the hoists must be able to brake effectively to hold the vessel in place. Added to this, are the inherent corrosion risks of a salty application environment, which can damage poorly specified equipment.
Putting the brakes on
Considering this balance between power, precision and reliability, a leading Italian winch and gearbox manufacturer approached Stromag, a leading brand of Altra Industrial Motion Corp., to provide a reliable and robust braking solution to be incorporated into shiplift hoists. The shiplift systems were destined for a shipyard which was aiming to improve its launch and dry-docking efficiency.
4BZFM Series electromagnetic, spring-applied, double-face brakes were specified, which are specialised for marine and offshore applications. Supplied in size 16/13, each provided a static braking torque of 130 Nm. Installed on the winch’s gearbox, the brakes provide stopping and parking functionality in the case of power loss. Each unit was modified to incorporate a special mounting flange and radial cable.
The 4BZFM is seawater-proof thanks to an IP67 ingress protection rating. Furthermore, all steel components feature special nitrocarburated and postoxidated surfaces to provide a high level of durability and corrosion protection.
The reliable, low inertia, high heat dissipation brakes are designed for easy motor mounting without the requirement to disassemble the brake. During braking, no axial or radial forces are generated. The brakes are highly serviceable and can operate without a cover.
Stromag is a global provider to the marine sector, offering power transmission solutions that can benefit shipyards. Furthermore, its global capability ensures responsive engineering and maintenance support for installations worldwide.