Rack-and-pinion railways
How did these unique transit systems help hefty locomotives scale steeper mountain slopes than ever before?
Arack-and-pinion railway (also known as a cog railway) was one that employed a toothed track. The addition of the toothed rail – which was usually loc ated centrally bet ween the two running rails – enabled locomotives to traverse steep gradients over 7 per cent, which remains to this day the maximum limit for standard adhesion-based railways.
Core to the operation of each rack-andpinion system was the engagement of the locomotive’s circular gears onto the linear rack. The rack and pinion t herefore was essentially a means of conver ting the rotational energ y generated by the train’s power plant into linear mot ion on the rack. As both the rack-and-pin ion gears had teeth, the system also ac ted as an additional form of adhesion to the track, with the inter-mesh ing teeth holding the veh icle in place when not in motion.