What Will the Future Bus be Like ?
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AN experimental chassisless bus built by the Birmingham and Midland Motor. Omnibus Co., Ltd., during the war had run more than 100,000 miles, and its structure had given no trouble, said Mr. D. M. Sinclair, general manager, in discussion at a Leeds meeting of the North Eastern centre of. the Automobile Division, Institution of Mechanical Engineers.
The discussion was on two recently published papers by Mr. Sinclair, outlining the history and present state of development in bus design and construction, and suggesting future tendencies. The under-floor engine was one of several subjects on which the papers aroused debate.
Under-floor Engines
Mr. Sinclair said that for maintename the under-floor engine was more accessible than in thp forward position. His company's mechanical staff preferred to work on under-floor engines, rather than on those normally mounted.
Mr. F. R. Cowell, of Kirkstall Forge, Ltd., did not agree that independent suspension should be fitted to a vehicle in order to improve its riding qualities.
A34 It was, he said,, possible to design any form of suspension, whether coil spring, rubber or leaf spring, to give similar riding quality.
Mr., Sinclair's criticisms of the leaf spring, by comparison with other forms of suspension, evoked a crisp reply from Dx, W. A. Tuplin, of David Brown and Sons (Huddersfield), Ltd. Remarking that Mr. Sinclair had cited gradual loss of efficiency as one of the disadvantages of the leaf spring, he said: " Other types of suspension have their disadvantages. For example, the torsion bar can have its efficiency reduced to zero in a fraction of a second, without any warning whatever."
On the same point, Mr. Cowell suggested that there was still something to be said for the leaf spring, in that it did not usually fail at once, but gradually, leaf by leaf, so that in a properly run maintenance shop the chances were that the weakness would be detected before the spring was completely out of action.
Mr. Sinclair felt that, if properly developed, independent suspension had something to offer for public service vehicles, and he was of opinion that it
would be largely adopted in that field within 10 years. His point about the leaf spring was not that it gradually became weaker, but that it grew stiffer as it became clogged with dirt and rust, and en buses the loss of resilience resulted in hard and uncomfortable riding.
Mr. Cowell qualified his support of Mr. Sinclair's suggestion that the twoleading-shoe brake appeared to have great possibilities for use on public service vehicles, offering a more efficient brake at a lower weight. There was much to be said for that brake, Mr. Cowell thought, if it obviated the necessity of boost. That was possible in the case of vehicles up to about 8 tons in weight, but on big vehicles the brakes must be boosted in any case.
Two-leading Shoes
Therefore, as the two-leading-shoe brake never had the same consistency of performance as the normal type, he felt that it would be far' better to have a slightly larger boost and use ordinary caliper brakes.
Mr. Sinclair replied that, although use of the two-leading-shoe brake would not obviate boost on the main types of bus, from 35-seaters upwards, the boost could be much lighter than would be required in the case a an ordinary brake. He also thought that, if properly designed, it would give more even wear of brake ,drums.
Mr. Sinclair added that the use of transmission hand brakes would greatly improve the layout of the wheels, eliminate complications and promote efficiency. fle doubted whether there was at present a commercial vehicle on the road in this country with an unboosted hand brake which was of any use except for parking.
Alluding to Mr. Sinclair's forecast that the chassisless bus would ultimately be universally adopted, Mr. Cowell said he had seen many such vehiclesunder construction in the United States, and replies to inquiries which he made there
suggested that they withstood service extremely well. It must not be forgotten. however. that Britain was exporting many buses, and a chassisiess bus would have to be shipped whole as deck cargo. He thought this factor was at the moment influencing British manufacturers against chassisless construction.
Mr. Sinclair replied that the same disadvantage applied to the Americans, our chief competitors in this field. At present. the old method of construction gave us an advantage in certain markets. but he was looking 10 years ahead. On the subject of automatic greasing, which Mr. Sinclair had suggested should be developed, Mr. H. N Tuff, of United Automobile Services, Ltd.. Darlington, thought it i,J,ould be better to obviate the nee(' for greasily: wherever possible.
Mr. Sinclair's suggestion that a much more efficient means for preventing mud-splashing was needed, prompted Mr. Tuff to ask whether any thought had been givento vi.nd-tunnel tests. Mr. Sinclair replied that it would pay to make such tests on mudguarding and he doubted whether the problem would he solved in any other way.