A PETROL-DRIVEN TRAMCAR.
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A Novel and Simple Transmission System which Overcomes Many Difficulties and Enables the Vehicle to be Run by the Non-mechanical Driver.
THE USE OF the internal-combustion engine for the propulsion -of railed traffic is developing rapidly. It offers many advantages over steam power in any country, and particularly wherever imported coal is expensive and supplies of native fuel do not exist, and also wherever the talent for managing a steam-driven plant is not readily available. It is one of the great claims of the petrol-driven engine and transmission that it can be managed by anyone assessing common sense, even if he lacks„mechanical knowledge and training. The electric vehicle is even better suited to the lower order of mechanical intelligence, because of the absence of the need for -gearchanging; but a supply of electric power involves many diffidult considerations, and, in the design of the transmission of the petrol motor tramcar, which we are about to describe, the gear-changing difficulty is reduced to such small proportions by the use of friction clutches as almost to warrant the assertion that, to all intents and purposes,-it does not exist.
The tramcar has been built for the Nasik tramway by IlInEwa,n, Pratt and Co., of Baguley Works, Burton-on Trent, and 13, South Place, London, E.C. 2. It is fitted with an open body to carry 45 passengers, the Canopy being suppvrted on 12 steel tubular columns and equipped with roll-up side curtains for inclement weather conditions, The backs of the seats are binged, so that the Passenger may face the way in which the vehicle is travelling, and a set of controls is arranged at each end of the vehicle so that the driver shall always be in front. A cowcatcher depends from each end cross-member of the frame and a wire mesh frame extends along either side below the frame and comes within a few inches of the rail level, a running footboard being hinged on either side of the vehicle to brackets on the side members of the frame.
The engine is four-cylindeeed, of 5 in. bore by in. stroke, capable of developing 45 to 50 b.h.p. at 1,000 revolutions per minute. It has duplicate ignition— magneto and coil and accumulator—and is -watercooled, a radiator being mounted at each end of the vehicle, interconnected by piping.
The transmission system has been patented, and in brief detail is as follows:—The gears a...e in constant mesh, simply being reduction or driven gears. There are two speeds, each being engaged by means of a disc clutch, each clutch being fitted to a separate shaft, the high-speed clutch being connected by a tubular shaft to its pinion in mesh• with the gearwheel on the bevel shaft, and the low-speed clutch being connected by a. solid shaft, revolving in the tubular shaft, to its pinion in mesh with the low-speed gearwheel.
In the starting Of the load the driver first operates his direction lever, which moves a dog clutch on the splined end-of one of the driving shafts, and thereby engages the forward or the reverse crown wheel, as may be desired, thus locking the crown wheel to one of the driving shafts. The other crown wheel runs idly in bearings on the other driving shaft. The driver now puts his speed lever from neutral to the one extreme which engages the low-speed clutch, and, having got his load under way, he immediately pulls his lever to the opposite extreme, thus changing from low to high speed without the disengaging or re-engaging of any gears whatever. This
avoids all the shocks and risks of shocks that occur in the use of the ordinary change-speed gear.
In climbing a glias dient whilst the high speed is engaged, should the load overhaul the power of the engine, the driver has merely to move his speed lever from the one position to the other, when the change is made without any difficulty, because the two clutches are always revolving in the same direction, one at the higher speed and one at the lower. The gearing gives speeds of 12 miles per hour and 6 miles per hour in both directions.
From the gearbox shafts (there is of course,. no need for a differential, as only one shaft is driving) the power is transmitted by silent chains to the road axle, the iron wheels being_of 28 ins. diameter' fitted with steel tyres:, 2-k ins, wide by ins. thick. The vehicle is mounted on the axles on laminated steel springs, which are carefully tested for the weights they have to carry.
e tanks have a capacity of 40 gallons of water and 20 gallons of petrol. Hand brakes are fitted to all wheels, the brake shoes being of cast iron and capable of being easily renewed. Such a vehicle should meet the difficulty experienced in towns and places where overhead wires are considered incongruous—the town of Hastings, for example.