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DCD's Jika Hydraulic Self-steering Bogie

There has been little significant development in bogie design since 1972, when prominent South African railway engineer Herbert Scheffel developed the self-steering model. His cross-anchor design, known as the HS bogie, is widely used in South Africa. Transnet Freight Rail (TFR) has about 200,000 examples in service currently.

A new milestone in the technology has been achieved by DCD Rolling Stock. In what is regarded as a major advance, the mechanical linkages that made the HS bogie steerable have been replaced with a simpler hydraulic system. Technically a passive hydraulic steering (PHS) bogie, DCD Rolling Stock's marketing department have dubbed it the "Jika". International patents for the Jika system have been lodged.

The use of hydraulics dispenses with the traditional cross-linked drawbars. This reduces the number of components in the redesigned, more cost-effective bogie, making the unit simpler to maintain. Lack of space within the frame of a bogie is largely overcome in the Jika system. This is especially advantageous when there are three axles on a locomotive bogie, the centre one having to accommodate both traction motor and braking system.

While the basic self-steering concept is well known, and the application of hydraulics to self-steering also has a number of patents already lodged, the current work by DCD is very much a pioneering effort. "This is the first time that hydraulics have been applied to the steering of bogies in South Africa," DCD technical manager Daryl Leggitt explains.

The major benefit of DCD's new hydraulically actuated bogie steering mechanism is that wheel flange wear is nabout eight times less than before. This will mean three times more life for the average locomotive wheel.
DCD is designing its Jika bogies with a focus on South Africa's heavy-haul lines, where axle loads of up to 30 tonnes are experienced. On the coal line and the iron ore line, replacement of train wheels is the major cost, Leggitt points out. With the performance of hydraulic self-steering bogies proven on rolling stock with the heaviest axle loading, it follows that it will be possible to retrofit locomotives and other stock having lighter axle loading.

This article was originally publissed on www.railwaysafrica.com

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