Longer Intervals Between Docks
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ANIETHOD ot determining the optimum period between replacements of parts, was described by Mr. I— Lagarrigue of the Paris transport undertaking during the discussion of his paper, The Organization of Repair shops and Depots for Motorbuses and Trolleybuses." He said that by running a number of buses in a fleet, subject to curative maintenance only it was possible to determine a lower critical mileage limit below which failure of components was rare and an upper critical mileage above which failure was
a certainty. .
Preventive overhauls could then be arranged so that parts that were essential to security, and the weakest parts, were replaced before the bus had covered a distance equal to the lowet critical mileage. Less important corn ponents could be left in service until the vehicle had covered a mileage which was near, hut below. the-upper critical limit.
To reduce the manpower to a mini mum it would be necessary to arrange the longer docking period in terms of tinte units as a multiple of the shorter period.
An Economical Measure
Preventive maintenance, said Mr. Lagarrigue. increased the total expendi lure on parts but reduced breakdowns and the number of vehicle's that would normally be withdrawn from service for repair. The total number of buses in the fleet could, therefore, be increased. ln the Paris undertaking, parts showing signs of wear were renewed immediately. Only high-quality replacements were used. which . was a servicing measure of great importance
Commenting on Mr. Lagarrigue's paper, Mr. A. A. M. Durrant, chief mechanical engineer (road services) London Transport Executive. said that the type of roof-suspended washing machine described by the author had been adopted in London in a garage of 100 vehicles it had been estimated that diet] use enadea the number of cleaning staff to be reduced by four.
By employing pressure in replenishing engine sumps, automatic cut-off fuel tilling nozzles, and large vacuum plants for interior cleaning in conjunction with roofand side-washing machines, buses could be serviced at intake intervals of four minutes. Fuel filling before garag ing for the night was practised in London. war-time experience with petrol-driven buses having indicated that the avoidance of a combustible air mixture in the tank was desirable
Night Staff Unskilled No skilled men, said Mr. Durran•L were employed in London on night work, but semi-skilled staff dealt with drivers' reports and so on at night Skilled work benefited from the improved day conditions and super vision. Since the war, routine inspections had been performed on the day shift when the vehicles came into the garage 'on spreadovcr."
The proportion of skilled to semi skilled and unskilled staff was Ito 8.4 at the garages and I to 0.9 at the works. The skilled men, concentrated at the works, could be employed more
efficiently. Apart from periodic oil changing, the removal of injectors and fuel pumps every 18 weeks, and the very occasional replacement of Cylinder-head gaskets, no work was done at the garages during the average of 2 to 24 years which the engines ran between overhauls, Engines were not removed until it became necessary because of noise, fuming or heavy oil consumption. This did not introduce difficulties in the overhaul of power units by the p roduct i on-flow method.
Mr. Durrant agreed with the author on the necessity of precautionary maintenance, but said that allowance should be made for technical improvements. These often represented a valuable servicing potential that was overlooked. In London there was a special planning section, under the rolling-stock engineer, in which maintenance schedules were continually checked in an endeavour to lengthen the periods between overhauls by eliminating measures which were no longer necessary.
As a consequence it had been possible to increase the period between " rota " inspections from two weeks to three weeks. The period between full-day dock inspections had been raised from 12 weeks to 18 weeks (18,000 miles) for buses operating in congested areas, and from 12 weeks to 24 weeks (24,000 miles) for buses in suburban areas.
Following Mr. Durrant, Mr. E. D. Norton, director and' secretary of Stratstone and Co., Ltd.,' said that three factors should be carefully cobsidered when a bus washer was purchased. These were the height of the garage, the siting of the w,asher and the contour of the vehicles' coachwork.
When winding up the discussion, Mr. Lagarrigue said that heating and ventilating were particularly difficult problems. The preparation of many vehicles for service in the mornings created a large volume of carbon monoxide which might be harmful.
Safety of the Single-decker
THE opinion that the design with
underfloor engines would not permit the development of a true low-loading version of the single-decker, was expressed by Mr. Durrant when summarizing, and elaborating on, his paper "Trends in Motorbus Construction." He said that some advanced features were introduced with the primary object of creating a selling point and that he was not sure the underfloor engine did not come into this category.
The reduction of high-frequency vibration when using coil or torsion-bar springing lessened the risk of metal B6 fatigue; the increased comfort with this type of suspension had to be experienced to be believed. Suspension points beneath the side members of an integrally constructed vehicle, said Mr. Durrant, represented a logical design because the members formed deep girders of light weight, and the wide base added to stability.
Independent suspension imposed the least wracking stresses on the shell; it should be possible to provide coil or torsion-bar suspension at the rear, in addition to independent front suspension, which would enable the load to be carried at the extreme sides of the vehicle.
In the discussion on Mr. Durrant's paper, Mr. E. R. L. Fitzpayne, general manager, Glasgow Corporation Transport, said that the single-decker should be generally adopted in place of the double-decker in the interests of safety, if for no other reason. Twenty-live per cent. of all accidents were platform accidents.
In Blackpool. single-deck trams ran a distance six times greater than the double-deck buses in Birmingham with the same number of accidents. A similaraccident average was recorded with single-deck trolleybuses in Darlington and double-deck vehicles in Kingston. although the mileage ratio was 3 to I respectively.
In Glasgow, said Mr. Fitzpayne, the results of using single-deckers with 26 seated passengers and 40 standing were under close observation. At peak periods, the single-decker carried an average of 119 passengers compared with 94 carried by the normal type of double-decker.
Other advantages of the single-decker included reduced body maintenance and easier cleaning.
The single-decker also offered the benefit of ease of standardization, which was of increased importance because of export requirements. Vehicles should be supplied with the opticn of two sizes of engine and two wheelbases. They should be of integral construction and have a combined exit-entrance central door; the ground clearance between the axles should be reduced to provide a low floor height,. Doors of the poweroperated, glider type should be fitted.
A plea ror greater uniformity of construction-and-use regulations at an internaticnal level was made by Coun. W. G. E. Dyer, vice-chairman, Nottingham City Transport committee. He said that this should be considered without delay.
Mr. A. Patrassi, of the Rome Transport undertaking, agreed with Mr. Durrant that the integral construction of single-deckers had not been fully developed. Such a design offered greater strength and reduced maintenance costs.
After describing the normal type of single-decker entrance as being too narrow and too high, Coun. S. P. Hill, chairman, Nottingham City Transport committee, said that there were doubledeck buses running in the Midlands which met the needs of children and old people admirably.
Opposing Mr. Durrant's views on propane gas as a fuel, Mr. W. S. S. M. Vrielynck, of the Brussels transport undertaking, said that the gas could be used successfully. This was shown by the performance of 20 buses running in Bruges which were operated more economically than they had been when running on petrol. They were greatly preferred to oil-engined buses on
account of their silence and because they did not emit odorous exhaust fumes.
The important part played by efficient windscreen wipers in improving driving conditions, was mentioned by Mr. J. A. Clark, technical sales engineer, TricoFri'berth, Ltd., who said that small blades operated by a small-capacity electric motor were inadequate to give the driver a clear vision.
Most public transport vehicles were, said Mr. Clark, fitted with compressedair or vacuum-assisted brakes, and the same sources of power could be used for screen wipers without affecting brake performance. Load increases up to stalling point were automatically compensated by an increase in power without danger of motor failure.
Replying to Mr. Clark, Mr. Durrant said that much windscreen-wiper equipment was too flimsy for rough usage. Commenting on Mr. Fitzpayne's claims for the single-decker he said that it was dangerous to generalize. In London the advantages of the double-decker were established.
Regarding an international standard of construction-and-use regulations, Mr. Durrant said that he agreed with Mr. Dyer, but thought that the costs involved would be very high because conditions varied so widely in different parts of the world. Replying to Mr. Vrielynck, Mr. Durrant challenged the statement that vehicles operated on propane gas ran more silently and with less disagreeable exhaust fumes than oil-engined buses. In special cases, operation might be more economic, but the general application of the gas was not practicable.
One-man Buses : Opinions Divided
TEN members of the congress took I part in the discussion on the paper "Operation of One-Man Cars in the United States," prepared by Mr. E. D. Merrill, chairman of the Board, Capital Transit Company, Washington. Many of the observations referred to the operation of motorbuses and trolleybuses.
Mr. E. Nielsen, director of Copenhagen Tramways, spoke from personal experience of American and Canadian public service vehicles, following a recent tour of those countries, He said that in all the towns visited he had deliberately paid the incorrect fare and had not been detected.
He considered that the fare-box system could not be used without severe financial loss.
The differential fares system, as employed generally in Great Britain, was, according to Mr. B. H. Harbour, operating manager, country buses and coaches, London Transport Executive, incompatible with one-man operation except in certain sparsely populated areas. The system encouraged passengers to travel short distances, and the Executive were convinced that buses operated by two men were the best for urban and suburban areas. The oneman bus would cause intolerable delays in towns.
Deputizing for the author of the paper, Mr. D. Q. Gaul, engineer of the Transit Research Corporation, New York, said that accidents had been reduced by the use of one-man cars and that the objections of the labour unions had been met by wage differentials. If improved living conditions in Europe prevailed, said Mr. Gaul, and competition by the private car increased, development of the one-man bus and tram would be inevitable to reduce costs.
Speaking for Mr. Perdrcau of the Lyons transport undertaking, Mr. M. Casson, of Le Mans, said that in France the one-man system was satisfactory in towns of less than 100,000 inhabitants and was justified in congested areas in off-peak periods. In Lyons, 120-seat vehicles operated by two men were advantageously employed.
Treadle-operated exit doors which required no attention by the driver, were represented by Mr. F. Delany, manager of international sales, National Pneumatic Corporation, Inc., New York, as contributing to the success of the one-man system in America, Mr. Delany emphasized that free circulation inside a vehicle was of first importance.
A speaker from Buenos Aires said that a micro-bus had been evolved by bus and taxi owners in the city to meet an urgent public need. Each vehicle carried 10 to 12 seated passengers and 10 to 12 standing, and of the total passengers transported by the various forms of conveyance, 22i per cent. used micro-buses.
The discipline of the general public was stated to be an important factor by an executive of Madrid Transport, who said that the system should be tried in conjunction with special instruction in schools. The occupation of the centres of towns in Great Britain by the working classes was given by Mr. W. B. I. Hofman, of Amsterdam Municipal Tramways, as the reason for the application of the differential fares system, which, he said, invited congestion.
According to Mr. A. V. E. Barquin, of the Brussels transport undertaking, the stopping time with one-manoperated buses would be more than the average of 5.6 sec. recorded by the existing two-men-operated vehicles. The average speed of the existing vehicles was about 10 m.p.h., whereas the introduction of one-man buses would reduce the averar to about 8 m.p.h. If the latter were used, loading should be at the rear and a fares-collection machine should be located in the centre.
Commenting on the speakers' observations, Mr. Gaul said that twoman operation added 25 per cent. to the cost of running a vehicle.
Madrid to Provide Overlapping Zone
IN the discussion on the paper "Pen tration of Surburban Services into Urban Transport Systems," prepared by Mr. Giupponi, of, the Turin transport undertaking and Mr. M. Paribeni, of Rome Transport, Mr. A. Patrassi. of Rome Transport, said that there should be complete separation between urban and suburban systems. Many different termini should be provided and a circular road built to connect the termini.
A zone in which urban and suburban services overlapped was recommended, by Mr. T. De Corral, divisional chief of Madrid Transport, who said that this arrangement offered the best solution to the problem. It would be adopted in Madrid.
The problem of providing for small residential areas was discussed by Mr. R. Maestrelli, —of Milan. The cost of providing each district with its own individual transport would, he said, be prohibitive, but if the population were content with buses serving urban termini, the cost would be reduced and there would be a greater degree of choice.