New Smart Components Optimize Productivity
Phil Burge, communication manager at SKF, looks at how growing demands on mobile and off-highway equipment are leading to a minor revolution in the development of small but nonetheless vital components such as actuators, bearings, seals and lubrication devices
The UK quarrying sector is among some of the oldest industries in the country. Driven by rapidly expanding requirements for aggregates and minerals, output has continued to rise over the years and today there are some 1,300 quarries in the UK producing £3 billion in products every year, which contribute to the building of around 180,000 homes and the maintenance of the UK’s 230,000-mile road and 10,000-mile rail networks.
For companies operating within the industry, the challenge remains to maximize output in an efficient, cost-effective and safe manner. Accordingly, the goal of all end-users and manufacturers of mobile, off-road and construction plant is to minimize operating and maintenance costs, while maximizing vehicle efficiency and life in service, even in the most extreme conditions.
In many instances, the key to achieving this goal lies not just in the performance of larger systems, such as engines and gearboxes, but in the smaller components such as actuators, bearings and seals; for if these vital but often overlooked components fail to function then system failure and vehicle downtime is almost certain to occur.
As a result, leading manufacturers have developed a new generation of components that are virtually maintenance-free and offer a far longer operating life under demanding environmental conditions. For example, electromechanical actuators are increasingly replacing hydraulic systems to deliver greater reliability and productivity with less risk of environmental damage through oil leaks. The increasing use of linear-motion devices is partly due to the considerable evolution that the technology has undergone in recent years and it is now considered as a proven alternative to conventional fluid-power technologies.
Electromechanical drive technology is typically quieter, more efficient and less expensive to operate and maintain than its hydraulic counterparts. While it is widely accepted that the cost of an individual hydraulic cylinder is less than that of an electric actuator, it is important to remember that a single cylinder accounts for just one part of an entire system, so it often means that a hydraulic system can be more expensive overall than the electromechanical equivalent. For example, electric linear actuators only need cables for the power supply and transmission of signals, or for connection to a field bus system.
In addition, the latest linear-motion systems generally offer superior motion capabilities, with linear drives often being used as reversing devices in many applications with oscillating movements occurring at high frequency. Acceleration factors of up to 10g can be achieved, allowing the reversing action to be performed without any penalties.
Just as importantly, the emission problems usually associated with fluid-power technologies do not occur with electromechanical systems, while the increasing sophistication of the technology also means that standard actuators are now available with load ratings of up to 100kN and strokes of up to 1,500mm. The latest designs are also particularly compact and streamlined. In addition, electric actuators offer a further advantage when it comes to control devices, as they can draw upon the wide range of electronic control systems available for electric drives, even rotational ones, while the low unit prices of such systems allows considerable cost savings to be realized.
Similarly, bushings produced from hybrid materials, with filament-wound polymer and PTFE fibres, have been introduced to extend the operating life of axle pivot joints on tractors and backhoe loaders. Likewise, the latest large-diameter seals from leading manufacturers, such as the HDSF2 seals from SKF, feature a PTFE excluder lip which is integrated within the body of the seal to protect bearings from the ingress of abrasive dust and particles in a wide range of mining and quarrying applications. In particular, the new HDSF2 seals are proven to allow the typical operating life of bearings in some equipment to be more than doubled, helping end-users improve productivity, while reducing repair and maintenance costs.
Bearings fitted with conventional seals that are used in plant and equipment exposed to high levels of abrasive dust are highly susceptible to rapid degradation of the bearing shaft surfaces and lubricants; this can often lead to premature failure within months of operation. To address this problem, the latest seals incorporate a number of innovations, such as elastomer sealing lips and metal cases, which have been designed to improve reliability and extend operating life still further. Extensive testing has indicated that the latest seals are twice as effective at preventing the ingress of abrasive dust and other contaminants than traditional lip seals.
Equally, sealed-for-life bearings, with self-aligning rollers, are being used to improve the performance and reliability of steering mechanisms in heavy haulage machines. Typically incorporating a CARB toroidal roller bearing in the non-locating position and a spherical roller bearing in the locating position, these self-aligning arrangements ingeniously accommodate misalignment to eliminate friction and provide smooth operation that minimizes the load on the bearings.
Likewise, fit-for-purpose bearing units, such as the SKF ConCentra roller bearing, can be used to increase efficiency in mining and quarrying operations by providing consistently reliable performance in these typically harsh environments, where heavy loads, shock loads and contaminants are common. As they are supplied pre-greased and sealed, and feature an easy locking system, the units can be installed or replaced simply and safely, eliminating the problems that are often associated with having to cut conventional bearing units from the shaft to replace them.
Just as importantly, adequate lubrication is needed for bearings to deliver optimum service life. Automatic lubrication systems are ideal for mining applications and can be fitted to equipment to dispense the appropriate amount of lubricant to the bearings at predetermined intervals. This reduces the risk of over- or under-greasing; ensuring machinery is able to provide consistently high performance.
This latest generation of components offers a variety of important advantages for operators and manufacturers of mining, quarrying, mobile and off-highway plant. By specifying these advanced components it becomes possible to ensure that equipment delivers enhanced performance, greater safety and functionality, with improved efficiency and productivity benefits, plus reduced capital and total-life costs.
For further information contact Phil Burge on tel: (01582) 496433; or email: [email protected]
