BRADFORD'S NEW SIX-WHEELED BUS.
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Devised to Give a Large Seating Accommodation, with the Load Spread Over Three Axles, Bradford's New Trolley-bus will Help to Overcome the Need for Replacing , Worn Tramway Tracks, 4 6 WHAT is the best. form of multi
sailed vehicle?" This question was asked in The Commercial Motor recently. Mr. R. H. Wilkinson, manager of the Bradford Corporation Tramways has responded by building a six-wheeled trolley-bus, which gives every prospect of satisfactorily meeting the objects which fed to its erection. Bradford has been considered to be in the forefront with its tramway undertaking for a number of years, Mr. C. J. Spencer (now of the London Electric Railways) initiating a forward policy, particularly in the constructional and engineering department, and this has been maintained by Mr. Wilkinson since his appointment as general manager.
Bradford is a difficult place so far as transport is concerned, the city lying in what is really a natural basin., formed by the convergence of several valleys„ and this means that, in whatever direction it is desired to travel, hills.a.re encountered. Apart from the difficulties with vehicles on the gradients, the hills tend to make the demand for passenger-carrying vehicles on the part of the pablic exceptionally heavy-, and the city has a Inlay tramway service converging upon two or three points in the comparatively small area about the centre, at the bottom of the basin. Frequent services make heavy demands upon the track, and now, just when the cost of replacement and renewal is. se high, the permanent way is in urgent need of attention.
To solve the,problem of the expense, Mr. Wilkinson has turned his attention to the trolley-bus, and, whatever may be the experience in other centres, Bradford provides an instance which suggests that, properly developed, there are immense possibilities for this form of transport.
The advantages of an engineering and production department, which has carried out the work in connection not only with the repair, bt also with the building of tramway vehicles and other important work in the maintenance of the tramway service, has been brought to bear upon the improvement of the trolley-bus: Where tramway track has not been laid down, a single-deck type of trolley-bus has been in operatiou for some years, but, when permanent-way renewal difficulties began to show themselves, Mr. Wilkinson turned his attention to building larger-capacity trolley-buses, and a double-deck vehicle, which has since travelled approximately 40,000 miles, was put. upon the road in November, 1920. This vehicle seats 51 passengers, and has proved highly satisfactory.
Not aathffied with this success, Mr. Wilkinson resolved to provide a trolley. bus which still more nearly equalled the capacity of the tramway car, in order that, where it was found uneconomical to renew the track, services which are at present in operation may be maintained, the source of power being already provided, and it being unreasonable to expect that the capital expended upon the generating station shodd be wasted.
The difficulty which presented itself was that, owing to the disposition of the weight of this type of vehicle, the strains
on the back axle were tremendous, and these strains were made all the more, serious by increased road shocks due to. the increased weight of the car.With a. view to overcoming the difficulty a sixwheeled vehicle was considered practic-able,however, and the result has been that Mr. Wilkinson has produced a vehicle which carries-but 50 per cent. of the load upon the rear wheels, the remainder being spread in equal proportion over four front wheels.
Actually, the weight of the new vehicle is less than that of the similar type of four-wheel vehicle which has been on the road for some time, but Mr. Wilkinson explained to a representative of The Commercial Motor that this was not a fair comparison, because experience gained in building the four-wheeler had been used in building the six-wheeler. The four-wheeler, for instance, weighs 7 tons 8 cwt., while the new six-wheeler weighs only seven tons. However, the weight of the new vehicle suggests that the addition . of two wheels does not necessarily add considerably to the weight.
The four-wheeled vehicle carries 51 passengers, while the new vehicle is fitted to carry 59 at present. The front portion of the upper deck of the new vehicle has not yet been provided with seating accommodation, however, but if this is used, as it is likely to be later, the seating will be increased thereby to accommodate 65 persons.
The addition of two wheels has been carried out without revolutionary changes in chassis design. the principal members of the chassis frame -being of H section and perfectly straight from back to front. Mr. Wilkinson told' our representative that he had first thought of designing the vehicle so that It should have what inight-be-termed two rear axles, but the complications which were introduced were too great when compared with any advantage which might be gained, and he instanced the difficulty of providing steering for one of the sets of driving wheels. The steering of both sets of front wheels is a comparatively simple matter. This has not been carried out on the bogie principle, however; the two axles are separate and the wheels run , on stub .axles, being steered from a central steering shaft, and all interconneCied.
The body is suspended upon huge coil springs working in pairs upon the front axles, and although up to the time of writing there has been no actual road test, the fact that the load is distributed to give less weight per wheel than in the case of a four-wheeled vehicle suggests that the running will be light, giving an advantage to the passenger, and also to the tyres and mechanism. The vehicle runs on. eight sets of tyres, it might be mentioned, the rear wheels having twin tyres.
We are anxious to know if the steering is at. all hard or stiff. The increased amount of steering connections and the need for moving four wheels instead of two must make a little difference, but 'more important still in effect is the more forward'disposition of the passenger load. For this reason we are rather sceptical about accommodating six more pa,ssengem on the canopy above the driver. On this point we are hoping to hear from Mr. Wilkinson so soon as he has carried out the road tests which he has in mind.
The drive is taken to the rear wheels from a. 70 h.p. motor through chains running from a countershaft, the differential being on the back axle. The Motor is controlled by a foot controller, and there are three brakes. An electric brake operates through the controller, a foot brake -operates on the countershaft, and a hand brake cheeks both the back wheels and the second pair of front wheels.
At iresent the powers of the City Council allow the operation only . of vehicles up to 5 tons weight, but powers are being sought to alter this, and, in the meantime, the Ministry of Transport has given permission for this new vehicle to be rim experimentally. It will probably be in service on one of the routes within a very short time. The corporation is also applying for an Order to run trolley-buses over a number of tramway routes, largely in view of the state of the track, and to provide extensions to outdistricts in continuation of these routes. If the Order is granted, it will be possible to rim a through service of trolleybuses to the out-districts without a break, and probably big vehicles of this type will be used. It it, of course, possible to run trolley-buses on tramway routes without any addition to the overhead equipment, a shoe being run in the tramline to provide an "earth" in place of using the " return " wire and the second trolley pole. It can be arranged that, when the shoe engages with the rail, the steering of the vehicle will become automatic, the wheels following the direction of the rail, but actually there is no reason for this.