What is a cogwheel train?

A cogwheel train is a train fitted with one or more cogwheels, which mesh with the toothed rail-rack, running usually between the normal rails. The system, operating on rack and pinion arrangement, is used in regions where trains operate on steep heights within a short span of time. Most cogwheel railways are mountain railways, although a few are transit railways or tramways, built to overcome a steep gradient in an urban environment. The first cog railway was Middleton Railway, UK. Now it is a major tourist attraction of Jungfraujoch, Switzerland.