Twiflex puts the brakes on offshore winches

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The action of waves can place significant tension on the winch cable when bringing two boats together.

The initial consultation began with Intertech B.V., which is the official distributor for Twiflex products in the Netherlands. As a technical trading company, it specialises in power transmission and motion control products, with particular focus on the petrochemical, power generation and marine sectors and has over 15 years’ experience developing Twiflex products for use in the offshore industry.

In this instance the OEM responsible for the vessel mooring system on the pipe-laying vessel approached Intertech for advice on caliper braking options for its new range of hydraulic haul back winches. Intertech was quick to suggest the Twiflex range thanks to its reputation for delivering reliable products into marine and offshore applications, as well as offering the largest range of industrial disc brakes in the world.

Alexander Kuhne, Managing Director at Intertech, comments: “Our experienced engineers have long appreciated the benefits that Twiflex designs can bring to our projects. The technical knowledge and support enables us to work closely with the client and deliver a bespoke package tailored to the specific requirements of each application.”

A brake system was required that would allow the cable to be gradually released in order to protect the winch when tension exceeded 30 tonnes.

A brake system was required that would allow the cable to be gradually released in order to protect the winch when tension exceeded 30 tonnes.

The purpose of this particular winch was to allow two vessels to be brought alongside each other using the cable to pull them together. However, the action of the waves between the two vessels can greatly increase the tension in the cable. This required a braking system that would allow the cable to be gradually released in order to protect the winch system when the tension exceeded 30 tonnes.

Twiflex was selected as the first choice for this project for a number of reasons including the compact dimensions of the VKSD-FL and its unique ‘parked-off’ feature which increases the ease of adjustment and maintenance.

Once the initial design specifications had been provided, the Twiflex engineers formulated a braking design that would enable a 30 tonne holding force to be maintained on the winch drum. Working with the starting point of a 660mm drum, the designers selected a 1500mm diameter brake disc and three VKSD-FL spring-applied caliper brake modules to ensure the complete system would have sufficient braking torque.

The VKSD-FL is a single spring brake module that is well suited to applications such as this, where space can be at a premium. This range also includes the ‘parked off’ feature, which addresses the risk of brakes clamping shut unexpectedly during maintenance.

Normally when spring applied brakes are powered down for maintenance work the brake is shut tight against the disc and as a result the springs need to be compressed by mechanical means to remove the pads. This process makes maintenance more time consuming and, due to the stored energy in the spring, leaves the brake prone to unexpected closure in the event of component failure.

The Twiflex ‘parked off’ feature is different to other solutions in that it actively removes the spring force from the brake while its powered off, meaning there is no force acting on the pad.

With hydraulic pressure applied, maintenance engineers can unwind an adjusting spindle, which releases the spring pack. When the hydraulic pressure is removed the springs have the freedom to extend without acting on the

The Twiflex VKSD-FL is a compact solution with a unique ‘parked-off’ feature which increases the ease of maintenance in-situ.

The Twiflex VKSD-FL is a compact solution with a unique ‘parked-off’ feature which increases the ease of maintenance in-situ.

brake. At this point the spring load and hydraulic pressure are both zero and the brake has no stored energy.

The ‘parked off’ feature has a number of benefits. First, basic maintenance such as brake pad replacement can be carried out quickly and with a reduced risk of unexpected closure when compared to conventional brake designs. Second, the brake force can be easily adjusted by setting the brake to ‘parked off’ and adjusting the number of shims from the end cover. Finally, installation is made easier and the brake can be installed without the need for hydraulic pressure.

For this project two winches were manufactured, each fitted with three Twiflex brake calipers to produce a combined braking capacity of 234 kNm. Each module is designed for over 2 million cycles which deliver excellent durability and spring fatigue life. The brakes were supplied for marine use and painted to ISO 12944-5 : 2007, C5 to meet the client’s specifications.

Alexander Kuhne concludes: “This demonstrates the ability of Intertech and Twiflex to deliver bespoke solutions that are designed to meet very specific requirements while also adhering to the specifications of marine design dictated by the regulatory bodies such as Lloyds Register.”

About Twiflex Ltd.

Twiflex Limited, with headquarters in Twickenham, England, specialises in the design, manufacture and supply of Advanced Braking Technology for industrial applications. With extensive in-house facilities, Twiflex enjoys a global reputation for quality. Founded in 1946, Twiflex has produced more than half a million brake units, frequently for safety critical duty, for applications around the world. From textile machines in the north of England to the world’s deepest mine shaft in South Africa, Twiflex brakes are specified by engineers and system designers in every type of industry.