A British Fleet of Trolleybuses for India
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Outstanding Features of Some Guy Vehicles That Have Been Built for Service in Delhi, Where Operating Conditions Present Certain Tricky Problems
QINCE 1908 the Delhi Electric Supply liJand Traction Co„ Ltd., has operated tramway services in the capital city of India, but the tramcars operate under difficulties by reason of the narrowness and congestion of many of the streets and the slow-moving bullock carts. In view of these conditions the company has kept a close watch on the progress being made by the trolleybus in different parts of the world. After careful investigation of various trolleybus systems in this country an order was placed with Guy Motors, Ltd., Fallings Park, Wolvethampton, for an initial fleet of 27-seater four-wheeled trolleybuses, and the chassis have now been shipped to India, where the bodies are being erected.
In view of the operating conditions peculiar to Delhi, in which the maximum speed is limited to 20 m.p.h., and the fact that the route is fiat, one of the vehicles is, for trial purposes, equipped with a super-saturated series motor, and it will be interesting to
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compare the results obtained with the working of the trolleybuses having regenerative motors.
The super-saturated series motor. although incapable of regeneration, possesses advantages over the ordinary series motor in that its field is wound with a large number of turns, so that in starting it is " super-saturated " and renders the machine capable of exerting a powerful starting torque. When all series starting resistance is short-circuited, 11 resistance units are successively connected in parallel with the series winding by a further movement of the power pedal. These resistances are so graded as to reduce the magnetic flux in the field in the degree required for smooth, but rapid, acceleration without any appreciable sparking between each contact,
Notwithstanding the special requirements of the Delhi concern, it has been possible to use standard units practically throughout the chassis. Roads in India are not designed for heavy traffic, and it is interesting to note, therefore, that the unladen weight of the new trolleybuses is only 4-4 tons. Because of the narrow streets the wheelbase and overall length of the chassis are less than usual, the former being 15 ft. 1 in. and the latter 23 ft.
The speed-limit regulation and the light weight of the vehicles have permitted the use of motors of only 35 h.p. They are almost identical with the 60 h.p. motors normally fitted in Guy single-deck trolleybuses. By using the standard 60 h.p. casing and winding the armature for only 35 h.p., the larger area thus available has the decided advantage of providing a coolrunning motor even under the extreme temperature conditions. It is fitted at the front of the chassis, the drive being taken, by means of a two-piece propeller shaft, to the rear axle, which is a standard Guy unit of the underslung-worm fully floating type.