The cog railway had been specifically designed for ascending steep
slopes, and, as such, it differed in several ways from a normal
railroad. Most railroads of the time used simply four smooth wheels,
turned by way of a piston, and this propelled the locomotive forward
along the tracks. But on a steep incline, these smooth wheels would
be unable to grip the rail tracks sufficiently enough to propel the
locomotive up the tracks. The cog railway, however, had a large cog
in-between the rear wheels of the locomotive, which would grip a
specially designed toothed middle rail on the tracks, and thus
provide sufficient power to ascend an incline. To prevent the cog
from turning backwards, and sending the locomotives hapless riders
and the locomotive crashing down the mountain, a small ratchet was
attached to the cog.
In addition to this, a gripper was positioned beneath the central
rail to prevent the cog from disengaging, and thus flying back down
the mountain.
Such a device was perfect for ascending the steep slopes of Green
Mountain. Seeking to improve upon the original design, Clerque added
a second cog, so that if anything were to happen to the first cog,
the railcar would be able to continue its ascent/descent until
repairs could be made without sacrificing the safety of the passengers.
