The variety of winch and hoist designs is vast and the number of applications almost too numerous to count. However there are some common features and design attributes that can be applied to almost every winch design. Martin Terjesen offers some advice on how to specify the correct winch drive
One of the most common requirements for a winch or hoist is that it must operate from within a restricted footprint. This leads to two initial design requirements; a compact frame and an energy efficient powertrain that will allow a smaller power source to be installed. These must be designed and manufactured in such a way that they also deliver reliability, which is the product of a number of variables including the raw materials, design expertise and manufacturing capabilities.
Why use a planetary gearbox?
Whether driven by hydraulic or electric prime movers, mechanical efficiency is key to optimising the performance of a winch system. Some traditional gear systems can have a mechanical efficiency as low as 50%. In comparison, a single stage planetary gearbox unit is around 98% efficient, even at very low speeds. Furthermore, by splitting the loads through multiple contacts between the planet gears (typically 3 or 4), the torque capacity of a planetary gearbox is favourable against other solutions of the same physical size.
In addition, Brevini’s planetary gearboxes come in a multitude of arrangements and versions, often with high radial load capacity from the output bearings. This makes them ideal for indirect drive applications, or where the unit must take the load of one side of the winch.
Using mobile cranes as an example, the common goal is to maximise the lifting capacity while minimising the overall weight, and in this the right winch drive can deliver a number of benefits. Space can be at a premium and so the ideal solution is to mount the gearbox inside the winch drum. By using a planetary gearbox, Brevini has developed a very compact drive design that can deliver strength and reliability for just such circumstances.
Many cranes operate using a multitude of hydraulic circuits, which lends the winch to be hydraulically powered as well; however the specification may require an electrical power source. In some winch designs this may affect the specification of the gearbox, but in Brevini’s case, its proprietary universal input design allows either power source to be mounted onto the planetary reduction.
Brevini’s own fluid power range allows for the perfect match of motor size and gear ratio; their engineers have one of the most complete ranges of fluid power and power transmission products in the market to choose from. Also working closely with electric motor manufacturers, this means a fine-tuned, bespoke solution can be provided every time.
Some of the largest winches are used in marine applications, especially for the installation of oil and gas pipelines. This type of application can require huge tractive forces and the gearboxes must be of sufficient strength and quality in order to provide reliable service.
It is important to ensure that every winch is specifically designed to meet the needs of each application and also designed to conform to the various industry standards such as those created by the European Federation of Materials Handling (FEM), which aims to develop technical standards for materials handling equipment across Europe. Many of the recommendations of FEM have been incorporated into national, European and international standards.
Marine approval authorities such as DNV (Det Norske Veritas) - now merged with Germanischer Lloyds to form DNVGL - require that certain marine equipment is certified; with basic product and manufacturer requirements being specified within their guidelines. Specifying DNVGL type approved equipment enhances safety at sea and helps to prevent marine pollution; it also allows for the free movement of equipment within the European Economic Area (EEA), consisting of the EU and AFTA Member States.
Brevini’s manufacturing facilities have been independently inspected and given type approval for these standards and its manufacturing processes by DNVGL and ABS (American Bureau of Shipping). These approvals cover the complete product range and demonstrate the high manufacturing standards that are maintained. In addition, full traceability of the raw materials can also be provided on request, which will meet most offshore as well as some military requirements.
Irrespective of the size of winch, it is important to ensure that the essential aspects of the design will suit the application in order to deliver a reliable end product. Working with a manufacturer that can design and produce the complete assembly will also ensure that efficiency is maximised and the drivetrain optimised for the application. Of course, all of this must be done while complying with the relevant standards that apply to the application.
Martin Terjesen is a Winch Specialist at Brevini.