Derby Commences Trolley-bus Working
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TurANy municipal authorities hold a 1.V.Lhigh opinion of the merits of the trolley-bus for passenger service, and the progress made by this type, of vehicle is indicated by the fact that, in this country alone, it is said that oVer i1,400,000 is now invested in this method of transport, whilst there are approximately 150 miles of route and over 400 trolley-buses in service. One of the latest municipalities to commence the operation of trolley-buses is Derby Corporation, which has started • a new service with a fleet of six Guy doublesaloon vehicles.
The chassis were built in the works of Guy Motors, Ltd., Fallings Park, Wolverhampton, and incorporate the maker's well-known system of articulation, in which twin cantilever springs on each side at the rear are connected to a central trunnion. The chassis are equipped with the Guy patented regenerative system, the motor being of the compound inter-pole regenerative type, rated for 75 h.p. at 500 volts at 000-2,500 r.p.m.
The control gear consists of the company's patented combined drum-type controller and shunt regulator, mounted in an aluminium case and actuating a B.T.H. contactor panel. A special form of reversing switch is provided, and this is mechanically interlocked with the control lever, so that the controller
cannot be operated with the switch in the " off " position. In addition to the regenerative braking, Westinghouse pneumatic brakes take effect on the four rear wheels.
The type of bodx which has been chosen for these vehicles is a 56-seater, built by the Brush Electrical Engineering Co. Ltd., of Loughborough, and it seats 27 passengers in the lower saloon and 29 persons in the upper saloon. Four half-drop windows are used in the former and six in the latter, and ventilators are used in the lower saloon above the main lights.
Ample lighting is provided by means of 10 lamps in each saloon. An auxiliary lighting set is installed, the current for this being obtained from a 12volt, 65-amp.-hour battery, a 10-ampere dynamo being positively driven from the motor. The dynamo supplies a Kathanode type-BK56 battery, this make being. employed also on the corporation's latest motorbuses. This system operates the two headlamps, a double trolley lamp, which is fixed on the roof to illuminate the trolley line, the tail lamp, an inspection lamp, a windscreen wiper and a horn. An automatic change-over switch is fitted in the driver's cab, so that, in the event of a trolley-pole becoming de-wired, the regulation lights are still in operation, as well as the horn and windscreen wiper. Two additional headlamps and a tail lamp are fitted, which are connected to the main current supply. Regenerative braking is effective at any speed above 12 m.p.h., and we are informed that, in case of emergency, the retardation is well over 5 ft. per second per second. Under these conditions, as much as 150 amps. at 550 volts can be returned to the line, and it is claimed that there are no main-road hills which the trolley-bus cannot safely descend, using only the effective regeneration as a brake. The vehicles are designed for a maximum speed of 30 m.p.h., and Guy Motors, Ltd., tells us that acceleration from rest to 30 m.p.h. is obtained in 14 sees.