The Straker-Squire Petrol Tramcar.
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The First 12 Machines are in Service at the Imperial International Exhibition at Shepherd's Bush.
The probable value of the independent, motor-driven, rail vehicle has for some years past. been a subject of considerable interest to the designers and constructors of road vehicles. It will be known to many readers of this journal that various efforts have been made in the past to produce machines of this class which should, in special cases, perform as satisfactorily under railway or tramway conditions as has the motor wagon, in all its various guises, on the common highway. In. stances of such enterprise may be found in the gas-engine-driven tramcars which met with a certain measure of success in this and other countries, in various designs of petrol-propelled and steam-driven tramcars, and in the incorporation of the internal-combustion engine into the designs of small railway locomotives. Various circumstances have hitherto combined to retard the full development of this class of work, and not the least of these has been the innate conservatism of many railway and tramway engineers and managers. As a practical exposition of the constructional possibilities of a self-contained, motor, rail-ear system, Sidney Straker and Squire, Ltd., of Nelson Square, Blackfriars, S.E., has afforded a workmanlike and satisfactory example in the recently-designed machines that have been delivered to the Exhibition Pleasure Car Co., and which are now running in the grounds of the Imperial International Exhibition at Shepherd's Bush.
From an inspection of the service in question, it would seem that these machines are not likely to enjoy ideal conditions under which to display their special advantages, as the authorities at the Exhibition have certainly not been too lavish in their expenditure upon the track, and, as yet, the attendances at the Exhibition are disappointing. It is certainly to be hoped that the " traffics " will increase as the season progresses and excursionists begin to arrive, so that
substantial data may be forthcoming with regard to these new StrakerSquire machines, which, under reasonable conditions, will, we Teel sure, give first-class financial results.
There are now 12 tramcars in the grounds at Shepherd's Bush, and they are all of the same type. We reproduce herewith line drawings of the plan of the underframe, and of the elevation of a complete car. Some delay was experienced at the outset, owing to the fact that it was uncertain as to which was the authority that should issue the necessary licences. Such constructions as the Mountain Railway, the Scenic Railway, and other combined transport and amusement undertakings in the Exhibition are licensed by the London County Council, but the licensing of the new tramway system has, after the necessary consultation, been taken over by the Metropolitan Police authorities, who limited the speed at which the machines were to run to 8 m.p.h.
The under frame of this new car is of channel steel, 6 in. by 3 in., and it is supported, at one end, by a centrepivot bogie of the usual tramcar type, and at the other end by a pair of driving wheels whose axleboxes are carried in hornplates in the conventional way. The driving wheels are 22 in., and the bogie wheels 20 in., in diameter. The general disposition of the engine, gearbox, radiator, and other units is similar to that which is now common
practice on the chassis of motor road vehicles. The engine is rated at 32 b.h.p., and is the latest StrakerSquire, four-cylinder, vertical type, with cylinders of รถ in. bore, and piston stroke of 5t, inches. This type of engine is in use in such numbers on omnibuses and vans in the streets of London and elsewhere, that a description of its mechanical features is unnecessary here. The drive is taken from the engine through a clutch, which is operated by a long hand lever, and this latter has a onenotch position on its quadrant, by which the clutch is held out of engagement. The speeds in the gearbox provide for two gears forward and one reverse. The cars are driven from one end only, and the control is conveniently grouped on the off side of the front platform, whilst the engine and driving gear are located symmetrically along the centre of the frame. It will be understood that this arrangement necessitates the employment of turntables at the ends of the lines, but we learn from Messrs. Straker and Squire that the designs are well in hand for further machines, in which a gearbox will be embodied that shall provide exactly the same range of speeds for both directions of travel. As adapted to the requirements of the licensing authorities, the tramcars have forward speeds of four and eight miles per hour respectively. Of course, there is no differential, but the drive is taken from the gearbox to the driving axle by means of a Morse silent chain of
in. pitch, and this arrangement can be clearly seen in the drawings which we reproduce. Any adjustment of the chain is effected by the sliding of the gearbox bodily forwards or backwards. The driving shaft, to permit extension, is finished with a castellated end, The gearbox is held down to the supplementary frame by bolts, which pass through slotted holes, and, in order that these bolts may not be kept under shear, locating adjustable setscrews are fitted, by which the correct radius may be maintained for the chain. The change-speed operating gear consists of two hand levers, one of which controls the two forward speeds and the other the reverse gear. The speed of the engine itself is controlled by a small accelerator pedal, which acts on the governor. The radiator is of the plain-tube type with cast top and bottom headers, and a fan of ample proportions is belt driven from the crankshaft. The whole engine is neatly covered in with a planished steel casing, and an additional cooling effect on the engine has been secured by the neat disposition of the exhaust pipe. This is carried vertically upwards from the roof into a silencer which is fitted overhead on the canopy. Surrounding this exhaust pipe is a brass tube, and through the annular space between these two pipes an induced draught of air is carried away from the inside of the engine easing during such time as the exhaust pipe is heated. The brakes are of tramcar type, and are operated by the usual screw-on hand lever ; the driving wheels are each provided with a pair of slipper brakes, and each bogie wheel is under the control of a separate brake block. The neat body-work is of the open type, which is so much in evidence in Continental tramway practice, and seating is provided for 30 passengers besides the driver and conductor. Suitable life guards are fitted, to the requirements of the licensing authorities, all round the vehicle, as may be noted.
These trams present a thoroughlyworkmanlike and carefully-designed appearance ; they bear no evidence of having been adapted from some other form of vehicle to the present requirements. Particular credit is due to Sidney Straker and Squire, Ltd., for the expeditious manner in which it has put through the work for these 12 machines, as the order was not definitely placed until the end of January, and, in spite of further delay in the matter of the settlement of details which should satisfy the licensing authorities to whom we have already referred, all the machines were delivered by the end of May. This energetic construction and the satisfactory working of the cars has already resulted in the receipt by Messrs. Straker and Squire of a very large number of enquiries, from all quarters, for vehicles to be constructed on this system, with various adaptations to suit local conditions in various parts of the world. In our issue of the 27th May, we published a short notice of these vehicles and then reproduced a number of photographs which were taken specially for this journal during the first week of Mr. hare Kiralfy's Exhibition at Shepherd's Bush, and after a trial run upon them.