Updated: 11 Oct 2003

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The Patiala State Monorail Tramway was the only known application of the Ewing Monorail Tramway system. Its aim was the cheapest monorail possible. With one rail, there has to be some way of stopping the locomotive and train from falling over sideways. The Lartigue Monorail straddled its single rail, so that rail had to be elevated above ground level, adding cost and making level crossings a rather surreal business. The Brennan Gyro-Monorail had a single rail laid at ground level, but required a complex system of double gyroscopes to keep it upright.

The Ewing System solved the problem by being not quite a monorail- most of the load went on the single ground-level rail, using double-flanged wheels, but some 4 or 5% of the weight was carried on a road wheel that stopped it tipping over. The small amount of load on the road presumably did not detract much from the low rolling resistance of the steel wheel-steel rail interface.
The road wheel would take exactly the same path each time, and on the unsurfaced roads of the day this must have tended to wear a groove; quite possibly the PSTM had a tendency to lean towards its road wheel. At least this would have been in the direction of increased stability. W J Ewing was a British inventor; he seems to have abandoned his attempts to patent the concept.

Left: The preserved Patiala monorail locomotive, in full steaming and working order at the Indian National Railway Museum in Delhi. Note the strip of concrete laid under the path of the road wheel. The PSMT was begun in 1907 but closed in 1927 due to rising competion from road transport. One engine was restored by the Northern Railway Workshops at Amritsar, and is in operation at the National Railway Museum of India.

Picture by kind permission of Prakash Tendulkar.

More of his pictures of this monorail can be seen at: http://www.trainweb.org/railworld/Trip%202001/PSMT/

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