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Gauteng-based DCD Rolling Stock launched its patented Jika passive hydraulic steering (PHS) system for locomotives earlier this month at the Trans-Africa expo, in Johannesburg.

Using the Jika will not only increase the life span of the average locomotive but also reduce track wear by 60%. Further benefits include reduction in energy consumption of 3% and in noise pollution.

Testing of the Jika PHS system is currently under way and is expected to conclude in the next six months.

DCD Rolling Stock MD Rob King stated at the launch that the Jika would revolutionise the locomotives industry and it would significantly improve operating environments and the costs asso-ciated with it.

DCD Rolling Stock GM Petrus Mulaudzi explained that one of the biggest challenges for rail operators was negotiating bends on the tracks, the impact of which included increased wear and weight on the rails, as well as energy use.

"The Jika reduces the cost of increased busi-ness by reducing the rolling resistance of loco-motives and enabling them to negotiate bends more efficiently. The more efficient the system, the more goods can come onto rail," he said.

DCD Rolling Stock product engineer and Jika PHS inventor Pat Smit said, in addition to decreasing the wear on the rail and on the locomotive wheel, the reduction of locomotive force also reduced the lateral movement of the rails on their sleepers, which resulted in the rails spreading apart.

"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 as stating that one test showed that maintenance on the curved sections of the railway system was reduced by 60 %," he said.

A device is fitted between the outboard wheel sets and is hydraulically interconnected to form a patented passive hydraulic logic system, which allows or restricts wheel-set movements to achieve self-steering on curves and stability on tangent tracks.

Specially designed double-acting cylinders, with operative front and rear chambers, are incorporated into the system. The cylinders are attached in a horizontal plane at the axle centre height, preferably on the diagonals through the journals.

The hydraulic cylinders are attached between the bogie frame and the leading and trailing wheel set, replacing the rigid con- necting link between the axle boxes and the bogie frame. This enables the outer wheel sets to yaw inversely, relative to each other, while restricting the relative axle longitudinal dis-placements, thereby creating the self-steer effect when negotiating curves.

Smit pointed out that traditional links and levers could be dispensed with when using a hydraulic system.

"This reduces the number of components in a bogie, making the steering subsystem easier to maintain. The Jika PHS also addresses the lack of space within and distance between the wheel sets of a bogie, particularly with regard to three-axle bogies, where there is a central wheel set with its traction motor and braking system," he said.

Smit added that the Jika PHS was specifi-cally designed for commercial freight lines, where frequent and small radius curves are common.

He noted that the replacement of train wheels was a regular and expensive process, as it involved infrastructural costs, locomotive downtime and work hours.

The Jika PHS will also enable the use of more powerful three-axle bogie locomotives, as opposed to the less powerful two-axle bogie models. This system is equally important to heavy-haul lines with axle loads of up to 30 t.

From Creamer Media's Engineering News at www.engineeringnews.co.za

Posted in: DCD Rolling Stock
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