Railway Track & Structures - July 2008 - (Page 24)

Technical report Figure 4 shows the correlation between maintenance, time and achieving maximum quality. Rail vehicles consist of various masses, which are linked by joints of different degrees of freedom and inﬂuenced by springs and dampers. When vehicles are in motion, these masses are interactive, a phenomenon known as multi-body dynamics. To enhance ride comfort through the diverging side of a switch, new high-speed turnout designs use a non-constant radius. To reduce jerking at the transition from the straight rail to the curve, the switch blade is modiﬁed by the inclusion of clothoid sections, whereby the initial radius reduces continuously towards the ﬁnal switch radius. Optimized turnout geometry KGO is an advanced method to further reduce lateral forces when a rail car enters a turnout. This design takes advantage of the use of the rolling radius difference between the two wheels mounted on an axle when the truck enters a turnout by bending a specially-designed stock rail outward. This increases the rolling radius difference and guides the axle movement in the desired direction. In a standard turnout, when a wheel makes the transition from the stock rail to the switch point the contact point between wheel and rail moves outward to a smaller rolling radius on the wheel. This has a negative steering effect, the axle starts to turn towards the switch point and the ﬂange of the wheel rides against the gauge face of the switch point. This results in high lateral forces and wear on the switch points. A KGO turnout makes better use of this rolling radius difference by an asymmetric widening of the gauge in the transition area of the switch. The gauge of the stock rails is widened in such a way that the wheels steer in the right direction at the right time. This avoids hard ﬂange contact of the wheels and the switch points, reduces the lateral forces and so also reduces the wear of the components. In these turnouts, the switch points become thicker more quickly, which makes the points more stable and, at the same time, gives more wear allowance. Turnouts for the Taipei-Kaohsiung (Taiwan) high-speed line have been developed using kinematics gauge optimization to improve ride quality when diverging at higher speeds. Better design should help to reduce wear and improve life-cycle performance. Turnouts 60E1/60E1A4 and 60E1/46 for the TGV East Paris-Strasbourg high-speed line use KGO to improve ride quality, as well. 24 Railway Track & Structures July 2008 www.rtands.com Kinematics Gauge Optimization (KGO) http://www.rtands.com

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Railway Track & Structures - July 2008

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