The solution is to mount a toothed rack between the running rails and provide a cog (pinion) on the locomotive.
In this way the locomotive can crawl up steep gradients. The system is cheaper to manufacture and install than other systems as it uses less steel.
The braking system also uses the rack to slow and stop the trains with the brakes fitted to the pinion axles on the locomotives and carriages.
In addition to this higher carrying capacity all four carriages will now have wheelchair access therefore allowing more users the opportunity to travel every day.
The carriage bogies have been designed and built by Hunslet Engine Company at the home of their parent company LH Group in Barton under Needwood.
The locomotive always runs chimney first up the mountain pushing a single carriage in front of it.
For safety reasons the carriage is not coupled to the locomotive.
There are seven different types of rack and pinion systems for railways but by far the most popular worldwide is the Abt system as used at Snowdon. The Rack at Snowdon utilises a pair of toothed racks offset by one tooth and two driven axles on each locomotive, each axle with a pair of pinions.