THE HOBART ELECTRICAL TRAMWAYS.
The Hobart Tramway Company is to be congratulated on having tho finest electrical street railway installation in Australasia, perhaps in the Southern Hemisphere. The work is now completed, and the running of the trams is daily acquiring smoothness and punctuality, The interruption to the telephone system is but slight, and is really very little cause for complaint. The system adopted is that known as the over-head wire system. In this the electrical current is taken to the cars by means of a wire suspended longitudinally along the track. This wire is carried by other wires stretched across the streets, and supported on poles placed on the edge of the kerbstone. The poles are also used to carry the feeder wires, which are necessary to keep the strength of the current uniform along the whole length of line. The conducting wire, as used by Messrs. Siemens, is made of galvanised steel, so that great i strength and durability is attained ! with a small, and consequently light, wire. This fact enables the overhead wire to be stretched tightly and . uniformly, the effect being less unsightly than is usual with this system. The total length of the tracks is i about ten miles. In some places the curves and gradients are rather severe, the steepest grade being on i the Newtown lin where for about fifteen chains the rise is about 6 per cent., or lin 16£. The rails have been laid by the Hobart Tramway > Company, and are ordinary 40-pound Vignoles rails, and guard rails are used along the whole length of the lines. The joints in the ir,on rails are bridged over with copper strips rivetted to the rails, so as to ensure good contact and thorough electrical connection. The circuit is completed through the rails, which are used as the return lead. Sidings are provided where necessary, and are arranged for a ten-minntes' service, which it is proposed to run along the various lines. The cars, which are particularly neat, are constructed principally of teak and ash, with mahogany window - frames, etc. They will seat twenty-four passengers inside, and accommodation is provided on top for twenty-four more. The roof is reached by a spiral staircase at each end. The current is taken from the central over-head wire by Siemens and Halske's rubbing contact arrangement. Two of these project above the roof of each car; the current is then, carried through insulated wires to the switch boxes placed on the platform occupied by the driver, to which are fitted appliances for starting or reversing the motor, and also to its . armature, which is geared to the car-axle, thence through the wheels to the rails on which the car runs, and so back to the power house, thus completing the circuit. It is the office of the motor-man to break this • circuit when no wishes to stop the car, or to complete it when he desires to proceed. The speed is regulated by means of a series of resistance coils, through which the current can ■ be made to pass on its way from the over-head wire to the motor. The resistance can be regulated, and the speed controlled, from each end of the cars. The cars are each supported on spiral springs with indiarubber cores. The brakes are mechanical, and can be' worked by the driver from either end. Two motors are provided for each car. They are Siemens' fifteen horse-power, and are geared to the axles with single reduction gearing working in oil. The motors and gearing are enclosed in suitable casings, which render them both dust and waterproof. There are three engines of Williams and Robinson's well-known patent central -valve, high-speed compound type. They are provided with a steam separator, and fitted with very sensitive governors specially designed for the work. The engines work at a speed of 350 revolutions per minute, and are directly coupled to the dynamos, which are designed to give the required output at that specd — engine and dynamo are fitted on the one bed plate. A tachometer is mounted to show the rate of speed at all times. There are three dynamos of Siemens' H.B. 36-21 compound wound type. They run at a speed of 350 revolutions per minute, giving off- 500 volts, and 250 amperes at terminals. The shaft of the engine and dynamo armature are directly coupled together, and carry a heavy fly-wheel 4ft 2in in diameter. The current from the dynamos is taken to a suitability - arranged switchboard, on which are mounted the necessary switches, cutouts, resistances, and instruments for measuring current and electro-motive force. Thence the current is carried by means of large insulated wires to the outside circuits. The approximate cost of Messrs. Siemens Bros.' part of the work is £34,000. and the whole of it has been carried out under the personal supervision of Mr. A. C. Parker, engineer -in - charge for Messrs. Siemens Bros.
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