Linear motion technology improves working conditions

A range of linear motion products from SKF is being used by Harmill Systems to develop an innovative inspection trolley device that is helping to improve the working conditions of maintenance engineers who spend long periods of time working below underground trains. The inspection system has already won an award for Safety at the Railway Industry Innovation Awards 2006.

Typically, the inspection pits underneath underground trains are far from ergonomic, with many being no more than chest high. Consequently Harmill Systems was appointed by Metronet, the company responsible for maintaining two-thirds of the UK's underground infrastructure, to develop a system that to improve the working environment for maintenance engineers.

Using a variety of the latest high-performance components from SKF, including stainless steel shafts, shaft blocks and linear bearings, Harmill Systems designed a mobile workstation that runs underneath the tube train. The travelling unit comprises a chassis mounted on wheels that rides on its own rail in the base of the pit. Two stainless steel shafts, held in place by shaft blocks across the chassis, act as runners for four linear bearings. These, in turn, support a small platform that holds a 19tonne bottle jack onto which a robust seat and seatbelt assembly, specially designed to withstand the rigours of the demanding engineering environment, are mounted.

Capable of travelling in the X, Y and Z axes, the maintenance trolley smoothly transports engineers the full length of a train, sometimes up to 60m, allowing them to access the required areas in comfort and with ease. Furthermore, engineers have full control of the side-to-side, up and down, full recline and 360degree swivel motion of the seat, thereby improving accessibility still further.

Patrick Hughes, Managing Director of Harmill Systems, explains: "There are many reasons why we decided to use these specific SKF products; for instance, the bearings enable the trolley to move ultra smoothly with precise control, the robust and rugged nature of the components means that they are capable of withstanding the harsh environmental conditions of the underground, while the design of them means that they are quick and simple to install and maintain."

Patrick continues: "Overall though, the main reasons for choosing SKF are the high-quality manufacturing and construction of its products, the proven operating efficiency and performance they offer, as well as the outstanding product availability and reliable delivery service."