As demands on hard-pressed infrastructure become ever greater, track-friendly bogies can offer real benefits for operators and track authorities alike.
Jim Longton, SCT Europe
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BARBER Easy Ride (BER) is a range of bogies developed for the primary suspension market-in other words bogies that have their springs located between the wheelset and the side frame. The current BER range has a maximum axleload of 25.4 tonnes, with a wheelbase of 2m for 25.4-tonne axleload (101.6 tonnes GLW), or 1.8m for a 22.5-tonne axleload (90 tonnes GLW) for service in Britain. The 1.8m wheelbase bogie is designed to operate at up to 25 tonne axleloads, but Britain is the only European country which specifies a 2m wheelbase for axleloads higher than 22.5 tonnes. The material specification and the construction of the bogie frame and axleboxes imparts high strength too. A high factor of resistance to abuse is built into the bogie, together with high resistance to failure or catastrophic damage in the event of a derailment. All safety-critical parts of the bogie are visible for pre-operational inspection, especially the brake arrangements. Rolling contact fatigue due to high primary yaw stiffness of the bogie suspension is avoided because of low bogie stiffnesses. BER is a track-friendly bogie. Wagons equipped with track-friendly bogies benefit from lower track access charges in Britain-a major saving in operating costs. Savings between track-friendly and conventional bogies on the same duty cycle can reach several million pounds per year. The bogie frame is constructed from cast steel and two welds. The welded joint between the bolster and the side frames is located in a low stress area. This type of joint is possible because of the design flexibility of the casting process. The combination of high UTS steel coupled with a high yield provides a high level of fatigue resistance with the result that the frame will require minimum maintenance. The passive axle steering feature of BER allows the wheelset to steer in curves. This has two major economic benefits. Wheel flange wear is significantly reduced, thereby extending wheel life. Re-profiling wheelsets and their early replacement is the single highest maintenance cost associated with bogie maintenance. As wheel flange contact is reduced the passive resistance of the wagon is reduced, meaning that it takes less power to pull the train. This results in lower fuel and energy consumption of the locomotive. All wearing parts of the bogie are designed for extended operating life and when the time comes, easy removal, economic replacement and refitting. Three-piece bogies with high unsprung mass and Y25 bogies with stiff vertical suspension, limited lateral and longitudinal freedom, and no axle steering can cause huge structural damage to the infrastructure in terms of track, ballast, and bridges. The damage is recovered in track access charges, yet the infrastructure owner's objectives should be to reduce the damage, not to charge for it! BER is a long-travel, soft-sprung, passively-steered bogie with load-dependent three-dimensional friction-damped primary suspension. It is the product of many years of experience in the design of railway freight bogies by the SCTE team of engineers. The soft vertical suspension reduces trackbed and ballast degradation, while the controlled lateral accelerations reduce track-shifting forces. These are the forces that effectively try to push the rails apart, particularly in curves and when the wagon is loaded.
The axle spacing of 2m combined with the soft suspension reduces the point load per metre. This is especially important with regard to bridges. BER is a very quiet bogie. Bogies that don't enjoy the benefit of axle steering generate high levels of noise in curves because the wheel flange grinds against the rail creating wheel screech. Steered axles significantly reduce this cause of noise. Bogies with clasp brakes and cast iron shoes also generate high levels of noise when braking. BER is equipped with push brakes and composite brake blocks, which further reduce noise levels. The soft suspension of BER significantly reduces ground-borne vibration. This is a major problem affecting buildings located next to railways and particularly lines with high freight traffic. Reduced ballast degradation reduces the need for quarrying operations and the subsequent road movement of high tonnages of ballast. The extended life of the BER bogie and the reduction in damage to track also has a beneficial environmental impact that is not readily appreciated. The longer life of the bogie components, the wheels and the track, reduces the frequency of recycling scrapped parts. This reduces emissions resulting from re-melting the steel parts and lowers the carbon footprint of BER compared with many other bogies, particularly the Y25.
dampened springs, oil/water SCT Europe's new Barber Easy Ride bogie could offer operators lower track access charges The passive steering ability of BER reduces rail wear because it reduces flange rail friction. Passive steering also significantly lowers the cause of railhead wear. Return to Index to Appendix "A"
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