Vesconite materials are designed with careful attention to tribological aspects and the effects of liner friction level on bogie steering and wheel wear.
Vesconite centre pivot liners allow bogies to pivot smoothly with low stick-slip effects. This is achieved with a static coefficient of friction that is close to the dynamic coefficient of friction. The smooth steering is thought to be the reason for observed increases in wheel life, since this would allow bogies/trucks to follow the track more precisely and smoothly, without jerking or remaining stuck at very small yaw angles.
Vesconite centre liners are self-lubricating and homogenous. This gives consistent low-friction and low-wear properties for an extended service life.
Centre pivot liners provide a reliable slip surface between the bogie bolster bowl and the wagon centre plate.
The Bi-Mat liner is a high-performance liner providing the right properties where they are needed. The ring liner and flat liner are each subjected to different loading conditions, so the materials should be tailored for the differences.
The ring-liner is exposed to flexural and impact stresses during installation and operation, whereas the flat-liner is evenly supported and experiences vertical compressive stress.
Hilube 20 is a resilient bearing material that is well suited to the tough conditions of the ring-liner.
The flat-liner controls bogie rotational resistance and stability. A high performance bearing material such as Vesconite Superlube is desirable to optimise bogie steering and reduce wheel-wear.
Vesconite Superlube has low-friction without causing bogie instability. This is attributed to unusually low stick-slip properties which dampen instability. Superlube is well suited to long-life components because it has very low-wear and the friction properties remain consistent with increasing wear and time.
Finally, the Bi-Mat liner allows the pivot bearing to perform well in extreme climates with large temperature ranges. A typical one-piece centre-pivot liner can change diameter by up to 1.5mm and requires large running clearances as a result. The Bi-Matt liner can function with tight running clearance across an extreme temperature range. Tighter clearances help prolong the life of the bearing by keeping abrasive dirt out.