Bearings take the strain under the train

SKF Engineering Products, the Linear Motion Division of SKF, has supplied products to a company designing a device that will help engineers who spend significant amounts of time working below underground trains. Its linear technology helped smooth the path for an interesting inspection trolley, developed by Leighton Buzzard-based Harmill Systems, that is set to appear in a number of different guises in other inspection pit applications across the UK. Back injuries are very high on the agenda of many companies as they attempt to address one of the UK's most common reasons for time off work. This was certainly the case for Metronet, responsible for revitalising two thirds of the 'Tube', as it addressed a potential area of concern at its Waterloo depot. It asked Harmill Systems to develop a support system for workers as they travelled, in a confined area, along the underside of London Underground trains. The inspection pit, only chest high, was not the most ergonomic working environment for the engineers. So Metronet, considering the health and safety of its employees, commissioned Harmill Systems to develop a device that would make the engineers' jobs a lot easier. Patrick Hughes, Managing Director at Harmill Systems, says: 'We have undertaken a lot of work for Metronet in the past from cleaning systems to engineering solutions. We have a reputation for innovation and Metronet regularly involves us in some of its more challenging projects'. The solution arrived at by the company involved a number of components from SKF Engineering Products, including stainless steel shafts, shaft blocks and linear bearings. It comprises a chassis mounted on wheels that rides on the rails in the base of the pit. Across this chassis, two stainless steel shafts, held in place by shaft blocks, acted as runners for four linear bearings which, in turn, support a small platform on which is mounted a 19t bottle jack. A seat and seatbelt assembly 'borrowed' from a forklift - which was up to the rigours of a demanding engineering environment - completes the assembly atop the bottle jack. Now the engineers are able to sit in comfort and travel the full length of the train (up to 60m in some cases) while also having full control of the side-to-side and up and down motion of the seat. According to Hughes: 'The feedback we have had from the 'train doctors', as they are known, has been fantastic'. 'We understand that there is now an argument as to who does the inspection underneath and who does the insides of the trains'. 'Before the trolley, the underneath was always the 'short straw' - not now though'. 'We chose SKF for a number of reasons'. 'The bearings it offered are exceptionally smooth, the design is very neat and easy to connect to, the materials used in the equipment is more than up to the harsh conditions and the company, through its website, offered us exceptional levels of design data and information'. 'Price and availability also came high on the scale'. Since this development, Harmill Systems has taken an order for another trolley that will run on wheels and, through word of mouth and internal publicity within the rail companies, Hughes expects a number of other orders for similar devices as the rail companies actively address potential health and safety issues.