DEVELOPMENTS IN LONDON BUSES.
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What Aluminium Wheels, Cushion Tyres and Improved Springing are Doing for Vehicle, Load and Road. New Maintenance Plant.
S0 satisfied are the directors of the London General Omnibus Co., Ltd., and its engineering department with the N.S.-type bus, with its dropped frame and lower deck platform, its single entrance gtep and the features which have BO materially increased the comfort of passengers, that they have recently placed a further order with the Associated Equipment Co., Ltd., for 400 chassis, bringing the number of the type that will have been constructed to 2,000. In order to make the statement quite clear, in the orders for these 2,000 chassis are not included those for components, spares and replacement parts, all of which utilized in the maintenance of the fleet are additional. It
may be definitely stated that no new design of bus is at present on the stocks.
Success of the N.S. Type.
No troubles have developed in connection with the design of this model, the worst that has happened being that one chassis here and there has not been equal to the standard in silence, but only rarely has any noisiness (only a comparative term when the great majority of the vehicles run as quietly as a private car) develop in use. Once a bus has passed the tests applied by the Public Carriage Department of Scotland Yard,Yard, it may be taken that it has complied with the whole of the requirements of the police, and the experience of the company is extensive enough for the engineering department to guarantee that nothing beyond occasional adjugtments will be needed until, at the end of the half-year, the engine is replaced by one from stock, the old one going through a process of 'thorough overhaul.
C20 Almost the only improvements that have been made have been in the use of aluminium strip on the edge of the platform, the brightness of which draws attention to the fact that there is only one step, and in the disposition of the vertical handrail, which serves to give a hand hold to the passengers passing to or from the upper deck. Placed on the edge of the platform, it has a deterrent effect upon the young man who likes to board the bus at speed. Well (as a heckler at a political meeting once said to Lady Astor, in retort to a tren • chant remark of hers): " Who would not?" As passengers do try to jump on the buses whilst they are in motion, any effort to preVent them doing so only adds to the danger, so the handrail has been set. about 8 ins. inwards. It is an improvement, but we still find it a discouragement unless one has both hands free..
The new rubber buffers which have replaced the helical steel springs between the axles and the chassis frame have proved a great success. They operate in cups and actually are more of an auxiliary spring than a buffer, reinforcing the loaf spring and thereby enabling lighter main springs to be used. They absorb a great deal of shock and have improved the riding qualities of the buses.
How Cast.alutninium Wheels are Behaving.
The use of cast aluminium wheels is proving successful. Nearly 300 are now in use on K. and N.S.-type buses, the longest mileage so far recorded being 60,000. No less than 30 per cent. of the wheel weight is saved by using aluminium in place of steel, and this reduction of unsprung weight plays a big
part in the reduction of vibration in the, vehicle and in the road. The castings are extensively ribbed so that the strains are as evenly distributed as possible, and we are interested to learn that no undue tendency to crystallize around bolt holes has been disclosed.
A great deal of research and experiment has been conducted in the effort to secure rubber tyres which shall be more resilient than the ordinary solid tyre, and with so much success that it is ,.hoped very shortly to standardize on a cushion tyre of special shape which will give the effect desired and at a cost not materially above that of the solid tyre. Besides providing more riding comfort, reducing vibration and the consequent cost of maintenance, and also reducing road wear and damage, the quality in a tyre to which a great deal of importance is attached is a minimum tendency to skid. But it is felt that much has yet to be done by road makers in the discovery and use of materials which do not become highly dangerous every time it rains.
New Tools at Chiswick.
Tho repair plant at Chiswick is always being added to. One new tool which can be attended to by one man carries out simultaneously the two operations of boring a pair of cylinder barrels and of burnishing a second pair, much time and labour being saved. There has been designed and installed a high-tension insulation testing set for magnetos. Prior to its use it was always found necessary to call in for overhaul a magneto after it had been in use over a distance of 15,000 miles. By first subjecting all insulating materials to a severe test, rejecting anything which failed to pass, the running period has
now been extended to 30,000 miles. When the test was first instituted the proportion of rejects of moulded insulations was, for a time, as high as 95 per cent. The figure has now been reduced to 3 per cent.
The testing set embodies a high-tension transformer capable of producing a peak voltage of 40,000, the periodicity, of which is consistent with the normal magneto working conditions. The insulator to be tested is fitted into a jig and immersed in a glass tank partly tilled with insulating oil. A sliding cover is then closed and the low-tension current switched on. A variable spark gap inserted in the thigh-tension circuit can be adjusted to suit the various types of insulator under test.
The process of building up worn parts of engines and chassis by electro-depasition has been adopted and a system has been developed in the laboratory of the experimental department, which gives admirable vesults. Some very excellent work in this direction is now being done, and we have had the opportunity of examining specimens, where the steel has been coated to a thickness of over a millimeter on the diameter, the part afterwards being ground down to size between centres. Where the nickel coating has been ground right through and the underlying steel exposed, the perfect adhesion between the two metals has been obvious.
A very interesting miniature motor sweeper has been developed by the Leers Co., Ltd., to rriet the requirements of the omnibus company in the cleansing of the garages. It is about one-half the site of the standard sweeper, is driven by a 9 h.p. two-cylindered oilcooled Bradshaw engine with transmission by e. two-speed gearbox and chain drive.
Another item of garage equipment is a portable pump and measuring device which is employed in supplying lubricating oils to each bus, whilst a number of Bowser petrol supply pumps have been installed, as well as various laboursaving devices.
As we mention in our editorial pages, there has lately been a revival of the rumours in the lay Press of an intention shortly to place on the streets a series of buses with covered top decks. The news is two years old, and was first given all that time ago by The Com.mercial Motor, and the idea is no far
ther advanced. The company has produced in the N.S. bus, the type suitable for such top-deck protection, but Scotland Yard has done no more than look at it and examine the figures indicating the angle at which an N.S. bus with top cover and a full upper deck load of passengers (the interior being empty) must tilt before it would tend to overturn. This angle is 36 degrees. An S. type bus with a top-deck cover reaches the overturning point at 32 degrees. Thus the N.S. covered top-deck bus is even safer than its prototype. It is extremely curious that the authorities should so long delay the sanctioning of so obvious an improvement to comfort and safeguard to health that the top. deck cover would be.