THE DEVELOPMENT OF THE LIGHT, FAST BUS.
Page 20
If you've noticed an error in this article please click here to report it so we can fix it.
An Interesting Paper by a Weil-known Bus Authority Read During the Show Period.
M. L. G. WYNDHAM SHIRE read a paper before the members of the Commercial Motor Users Association on Thursday and dealt with recent developments as they affect the maintenance of motorbus services. Mr. Shire is chief engineer of the Birmingham and Midland Motor Omnibus Co., Ltd. lie dealt with the position of motorbus operating concerns after the
• war, showing that there was then an excess of 3-4-ton chassis of the goods-carrying type, the manufacturers being stocked with parts and materials and the number of ex-service vehicles being enormous. The result was that there was no manufacturer to whom motorbuSoperating concerns &add look for a passenger-carrying vehicle specially built for the work, as was the omnibus built for the London General Omnibus Co:, Ltd., for work in London.
It was, of course, a question as to whether a specialized omnibus chassis at that time would 'have met with much demand, because the price would have had to be high in comparison with the price of ex-service vehicles.
The Pneumatic-tyred Small-capacity Bus.
As time went on, and towards 1921 and 1922, the area of provincial omnibus services had increased very considerably and vehicles were now operating on roads whieh in the earlier days would have been left alone for many reasons. The road authorities made an outcry with regard to the damhge being done to the roads by heavy vehicles, and about this time great strides were made in America in the production of lightweight chassis operated on pneumatic tyres, a number of these types making their appearance in this country. The chassis of these vehicles were extremely light and the component parts were robust. Passengers found that they were comfortable for riding, whilst they were fast on the road, so that the competition from this—which might be called the 30-cwt. type of American vehicle for passenger work—was being seriously felt by the provincial operating companies, who were themselves running heavy 3 to 4-ton chassis on solid tyres. Mr. Shire's own company purchased a number of the 30-cwt. American vehicles in self-defence, and, after making one or two necessary alterations in brakes and steering gear, these vehicles gave satisfactory service.
With the rapid development of passenger traffic on the roads it became necessary to develop a chassis des:gned solely for the purpose of carrying passengers, and, after a great deal of trial and error, the Birmingham and Midland Motor Omnibus Co. produced a singledeck bus with a capacity for seating 32 passengers,
c36 the sum total weight of the unladen vehicle being well under 75 cwt. Numbers of these vehicles have each now completed close upon 100,000 miles, and Mr. Shire says that he is more than satisfied with them. They have proved reliable and economical to maintain. This vehicle has always been known as the S.O.S., and at the present Show, said Mr. Shire, there is a number of vehicles which appear to have got clear of the wartime lorry type, and at last manufacturers have reached a form of vehicle which should give a service closely approximating that given by private cars.
These new types of buses are going to have a farreaching effect on the passenger transport of the whole country, because of the great comfort that they offer.
Two great points in connection with these vehicles, apart from engineering details and lightening of reciprocating parts and the better power output obtained, are the lightweight body and pneumatic tyres. The bodies have been reduced enormously in weight by the use of light timbering and of sheet-metal brackets in place of heavy forgings, and the cutting down of the size of the under-framing members, pillars and roofs. The pneumatic tyre, apart from its own advantages, has made possible the use of such light coachwork, whilst the action of the tyre appears to smooth out the small, annoying body rattles. Remarkable mileages have been obtained from these tyres, and there is a great advantage in being able to replace a punctured or worn-out cover without upsetting the alignment and 'adjustment of the bearings, and without having to change the entire wheel, which, in the case of rear wheels, often means the fitting of new shoes or brake drums. The 6-in. tyre at the front and the 8-in. tyre at the rear for the 32-seater coach (with an additional eight allowed to stand), although slightly overloaded according to the manufacturer, is quite capable of giving excellent service.
Mr. Shire dealt with the proposed new regulations which would allow a bus of an unladen weight of not more than 31 tons to he accorded a legal speed of 20 m.p.h. He thought that it would not be difficult to produce a vehicle coming within this weight limit, but other limitations suchas in overall length, overhang and other dimensions were not so easy to comply with.
He dealt with various chassis items, such as quietness of power unit, and favoured the single-sleeve-valve engine if it could be designed to give the same efficient running and power output over long periods as the poppet-valve engine. The clutch should have the lightest possible spinning member. This can best be obtained by the use of the single plate.