en.wikipedia.org/wiki/Ewing_System

en.wikipedia.org/wiki/Patiala_State_Monorail_Trainways



Cheaper to build and to maintain, and less engineering required. Wonder why it hasn't seen more uses, thoughts?


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The railways based on the Ewing System are basically monorails using a
balancing wheel for balancing the train. The main load (almost 95%) is
borne by the single rail while the rest is borne by the balancing wheel
which runs on the ground. Further, in normal train systems, the rails
have to be at almost exact level of other rail, failing which the train
may go off the tracks. By using Ewing system, this problem is solved as
the balancing wheel does not need exact level to maintain the balance of
monorail. In addition the cost of laying tracks also goes down
considerably since only one rail is used. Another benefit of using Ewing
System was that the balancing wheel could run on existing tarred roads
as well as the macadam roads thus further reducing cost to lay down
tracks.



Using one rail also means that the turning circle is far less than the
standard trains. PSMT had to pass through some very congested areas.
Since the space need to lay the tracks was less and balancing wheel
could run on existing roads, PSMT succeeded in running through the
congested urban areas of Patiala. The balancing wheel of PSMT ran on the
roads and did not interfere with normal traffic.



The major benefit of trains is that they run on steel tracks. Steel rail
can carry more load with less rolling friction than any other mode of
ground transport. However the major problem with laying steel tracks is
that both rails have to rise and fall and bank together. Further, laying
two tracks also requires more space and more maintenance. Also the
turning radius of the train is restricted by the difference in length or
distance traveled between the inside and outside rails is a factor in
curve resistance. Curve resistance means that the wheels on the inside
rail travel a shorter distance than the wheels on the outside rail to
get the vehicle around a curve. The trains can only turn to the limit
where its outer wheels can cope with additional required speed. In case,
the outer wheels fail to maintain or reach the required speed, the
train may derail.



W.J. Ewing implemented a monorail system, with only one rail and double
flanged rail wheels, that had been proposed by William Thorold in a
lecture to the British Association in 1868. This system avoided all
those problems, since it was laid out along the side of a road, it took
up very little land. Further, the road or balance wheel's main purpose
was balance the train and to keep it upright. The balancing wheel on the
road carried only 4% or 5% of the load, it did not subtract much from
the steel wheel-steel rail efficiency. As the track was on side of the
road, it was no obstacle to vehicles crossing it. Further, since it was a
monorail with a supporting wheel on the ground, the issue of curve
resistance did not arise in Ewing System, since the wheels were placed
on a single track only.