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Johannesburg-based DCD Rolling Stock has revolutionised international railway logistics by increasing the lifespan of the average locomotive wheel by three times while reducing track wear by 60 percent and energy consumption by three percent - through the development of its patented 'Jika' passive hydraulic steering (PHS) system for locomotives.

As a division of international manufacturing and engineering company DCD Group, DCD Rolling Stock has established itself as a leading supplier of locomotives, wagons, bogies and related equipment to local and international railways, mining and industrial operations.

DCD Rolling Stock product engineer and Jika PHS inventor Pat Smit indicates that the company's latest technological breakthrough in hydraulics, which is officially being trialled in full rail service, serves as a more efficient, reliable and cost effective alternative to the current mechanical linkage system for locomotives.

In addition to minimising wear on the rail and locomotive wheel, the reduction of locomotive force also reduces the lateral movement of the rails on their sleepers that results in the rail spreading apart. Smit says that it is important to note that the Jika PHS also reduces the angle of attack between wheel and rail. "A prominent overseas locomotive manufacturer is on record that one test showed maintenance on the curved sections of the railway system reduced by 60 percent," he says.

The Jika PHS is also beneficial for traction and braking, but most importantly, the system reduces the rolling resistance of locomotives when negotiating curves, consequently reducing energy consumption by three percent. Secondary benefits of the Jika PHS are that the system makes the locomotive more universal for use on lighter rail sections, thereby reducing the fleet number. Tertiary benefits include a smoother and almost silent ride, and less pollution as steel particles ground off moving wheels are all but eliminated.

"Mechanical linkage systems in locomotives have proven to be inefficient, as a large amount of time and money is spent on maintenance. Bearing this in mind, DCD Rolling Stock began research on a more user friendly and cost effective solution for locomotive bogie steering and maintenance in 2009," he adds.

Smit points out that by using a hydraulic system, the traditional links and levers can be dispensed with. "This reduces the number of components in a bogie, making the steering sub-system easier to maintain. Another issue that the Jika PHS overcomes is the lack of space within, and distance between, the wheel sets of a bogie. This is particularly relevant in the case of three-axle bogies, where there is a central wheel set with its traction motor and braking system."

Smit points out that the Jika PHS has been specifically designed for commercial freight lines, where frequent and small radius curves are common. "The replacement of train wheels is a regular and expensive process, as it involves infrastructural costs, locomotive downtime and man hours. The use of the Jika PHS will also permit the use of more powerful three-axle bogie locomotives (Co-Co), as opposed to the less powerful two-axle (Bo-Bo) bogie models. This system is equally important to heavy haul lines with axle loads of up to 30 tons."

According to Smit, another major benefit of the Jika PHS is that it can reduce flange wear eight fold. "This design benefit will ultimately extend the lifespan of the average locomotive wheel by three times, thereby ensuring greater efficiency and substantial savings on maintenance."

Proven performance in testing

DCD Rolling Stock has been undertaking concept testing on the Jika PHS products since 2010, and is currently in discussions with various rail operators worldwide to undertake in-service testing in other environments to validate its initial data.

Using instrumented wheel sets that measure and record the force that locomotives impart on the railway line, DCD Rolling Stock engineers discovered that the Jika PHS reduced lateral forces by a factor of five in curves on these long wheelbase bogies. "During one test, official data revealed that a four ton existing lateral force on the rail was reduced to just 800 kg," claims Smit.

Following these successful tests, the Jika PHS bogie was retrofitted onto bogies on three locomotives in August 2013, and will operate in full service. The Jika PHS bogie will be compared against six similar locomotives fitted with conventional bogies for a six month trial period, starting in September 2013.

DCD Rolling Stock technical manager Daryl Leggitt states that this is the first time that hydraulics have been applied to locomotive bogies in South Africa. "Three locomotives have been fitted with Jika. The first two have already done over 11 round trips of approximately 11 000 km, in addition to three round trips of 3 000 km respectively. The trips were all fault-free."

This 'real-life' application testing process is being undertaken to focus strongly on wheel tread and flange wear reduction. Aspects such as improved serviceability, reliability and maintainability will also be studied. In addition, noise levels and the lateral wheel-to-rail forces will be recorded.

Smit believes that by adopting the Jika PHS system, customers will be able to save on the cost of replacement parts, in addition to minimising locomotive downtime. "Previously, there was a system of measuring and matching the wheels in the sets on a bogie. This was replaced by under floor lathes, which allow wheel treads to be cut without the need to remove the wheels from the locomotive."

Although this minimises locomotive downtime and labour, the disadvantage of this system is that the lifespan of the wheels are substantially reduced as a result of sacrificial machining, almost always as a result of flange wear. The use of the Jika PHS on bogies will reduce the need for excessive cuts on the wheel treads to restore the profiles.

Despite the significant progress made on the development of the Jika PHS, Leggitt admits that a number of additional in-depth tests must still be undertaken by DCD Rolling Stock. He also reveals that the company has been working in conjunction with a leading university to design a hydraulic cylinder unit that is capable of six years of maintenance free operation. "The hydraulic cylinder will also feature a rugged design, as it will be exposed to numerous hazards such as high acceleration, possible pressure spicks, heat, vibration and flying stones from the track."

Another challenge facing DCD Rolling Stock in challenging economic times is the fact the implementation of the Jika PHS system will involve some additional upfront costs. Leggitt does, however, stress that the overall lifecycle cost of the Jika PHS system will be considerably lower than traditional bogies in the long term. "The initial cost increase will be minimal and, taking into account that the Jika PHS extends wheel life by up to three times, it should pay for itself in a matter of months."

DCD Rolling Stock officially filed the patent for the Jika PHS in May 2013. This patent extends to countries including; Australia, Austria, Brazil, Canada, China, France, Germany, India, Russia, South Africa, Sweden, Switzerland, Ukraine and the USA. With this in mind, Smit is confident that the Jika PHS will be a game changer in the local and international railway sector.

"Adaptability is the key to DCD Rolling Stock's renowned innovation, and the development of the Jika PHS bogie is a technological breakthrough that will make railway logistics more efficient and competitive on a global scale. Looking to the future, it will be possible to fit these bogies to new locomotives and retrofit them to existing locomotives too. As a result, I am optimistic that DCD Rolling Stock has unlimited potential for growth through this new system," he concludes.

Since 1944, DCD Rolling Stock has produced over 130 000 wagons, 1 000 surface and 4 000 underground locomotives and over 278 000 bogies. In addition to revolutionising the global railway industry through the Jika PHS, the company will also create sustainable employment opportunities by aiming to source 90 per cent of its materials locally.

The Jika PHS was officially launched at the TransAfrica Transport, Infrastructure and Investment Expo, which was held at the Nasrec Expo Centre from 1 to 4 October 2013.

This article was originally published on http://www.supplychainonline.co.za

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