• Home
• Used vehicles
• Product news
• Dealer news
• Compliance
• Buying advice
• Archive

LU

in Road Transport

QMMENTING on the contrast between the early use of aluminium cars and its first appearance on corn rcial vehicles in the U.S.A. in the late 920's and early 1930's, Mr. Swoboda aid that the relatively short journeys and ow payloads of those days precluded full ealization of the benefits of weight aving. Also, operators wanting Turninium vehicles either had to build heir own or have them specially contructed.

AS highways were improved and !xtended and traffic grew, vehicles tecame larger and weight reduction tecame increasingly important in achievng profitable running and meeting .tricter legal limits, so that demand grew .apidly and today all trailer and truck nakers in the U.S.A. offered a line of ight-wcight vehicles. By far the greatest imount of aluminium for commercial /Aides was used in trailers (including ;emi-trailers). in 1950, production of iteel and aluminium van trailers was bout equal, but by 1954 the ratio was : 1 in favour of the aluminium type and )5? 1960 was over 3: 1. More than 80 ser cent. of insulated and refrigerated an trailers were now aluminium.

A typical 40-ft. " all-aluminium " van -railer used about 2,000 lb. of aluminium, t.xclusive Of running gear; about one-, third by weight was in sheet and twohirds in extrusions.

One early use was for dump truck Indies, easily made up from simple plates tnd extrusions and commonly offering SO per cent, weight saving. Extensive ise in coaches began about 30 years ago :o meet demands for better performance ind lower upkeep; as buses became .arger. more use of aluminium enabled them to stay within legal weight limits. A modern 40-passenger inter-city coach used about 5.400 lb., but school buses, which outsold inter-city types by 30 :/, Jsed very little since they had low utilization and low loadings.

Aluminium used in commercial vehicles amounted to about 150,000,000 lb. in 1955, rising to close on 200,000,000 lb. in 1961. The expansion, especially from the insignificant quantities used 30 years ago, was largely through ;mstomer demand and not through promotional selling by manufacturers.

Experience on the European Continent ROBERT GADEAU Aluminium Francais ALTHOUGH the Compagnie Generale des Omnibus de Paris used aluminium panelling on wooden framework as far back as 1910, and some small road tankers were also made in the same period, it was not until 1918-20, said M. Gadeau, that any important applications were found for aluminium in commercial vehicles, first as cladding and, more recently, for structural members. But it was not until the 1938-48 period that integrally constructed bodies appeared.

As well as pistons, universally made in aluminium allays, numeroug engine, transmission and running-gear parts were now produced in light metal, offering weight savings of at least 50 per cent. The total passible saving in a modern two-axle lorry with six-cylinder, 150-h.p. engine was more than 400 kg. (880 lb.). The weight -of aluminium used in mechanical components on heavy vehicles had doubled in the past five years, and the ease of machining aluminium alloys could offset the lower price of heavier materials.

Used on buses and coaches, aluminium panelling proved-light and easy to work. Integral construction in the form of a " box beam" gave the greatest weight saving; many European designs had been developed, usually of riveted construction but sometimes with spot-welded sub-assemblies. The present tendency was towardS use of pneumatic suspension with aluminium bodies, not only to improve comfort but also to reduce dynamic overloads on the structures.

All European countries now built aluminium tankers, said M. Gadeau, but the degree of development varied from country to country; in Germany, 85 per cent, of semi-trailer tankers were in light alloy, mainly because German regulations stipulated a minimum thickness for wrapper plates.

In Switzerland, and more particularly in Italy, a market had rapidly developed for truncated conical containers mounted

on lorry or trailer chassis for the bulktransport of powdered goods.

The use of aluminium had developed rapidly in Europe in recent years, both for vehicles with chassis-mounted bodies and for artics, Its employment for the panelling of vans was growing especially quick. Ever-increasing competition and the wider field of operation within the Common Market would place a premium on lower maintenance and operating cask and increased payloads, which seemed likely to extend aluminium's use in road transport.

Economic Aspects of Aluminium in Road Vehicles D. L. JONES Aluminium Development Association

IN this paper Mr. Jones summarised the I results of a survey undertaken to establish the magnitude or savings that could be expected for various types of vehicle and operation. It was shown that higher payload capacities, when fully utilized, improved efficiency and led to substantial cost savings. Moreover, maintenance costs or aluminium structures could be appreciably tower than when using more traditional materials.

The point. at which further expenditure on weight reduction was no longer met by an economic return, he said, varied between wide limits with the type of vehicle and the character of the traffic.

The items of operating costs which were affected by the use of aluminium were payload capacity, fuel consumption, tyre costs, licensing charges and maintenance costs. Whilst the price per ton of aluminium could be six to 10 times as great as traditional materials, because of their respective strength to weight ratios the amount of aluminium required to replace steel could increase material costs by two to three times.

An assessment of the benefits of weight saving should preferably be based on comparative data from records of vehicles operating over a fair period of time under normal service conditions. A survey had therefore been undertaken by the Aluminium Development Association in which 38 firms had co-operated, ranging from small private operators to large industrial concerns and public undertakings. It was found preferable to compare groups of vehicles, rather than single ones, to minimize random effects and factors other than vehicle weight.

Relative to payload capacity a firm operating both timber and aluminium bodies on bottled beer delivery obtained 11 per cent, more payload when using aluminium, providing an annual profit of £47.5 per vehicle after. all interest had been accounted for, A sand and gravel company achieved a similar additional payload, but because of the higher annual mileage-40,000 as compared with .20,000 in the previous example--achieved a corresponding annual profit of £113. •

Regarding fuel consumption, there were several extraneous factors which could affect a comparison of fuel costs obtained from either aluminium or traditionally bodied vehicles, and a comparison between large groups of vehicles was preferable to obtain a reasonably accurate assessment. Thus two groups of 50 double-decker buses were examined over a period of 3+ years. There was a weight saving -of 131 cwt. by the use of aluminium, and over a vehicle life of 15 years the annual saving set the upper limit of economic capital investment at £600, or £995 per ton of weight saved.

A tyre manufacturing company has reported that at the 100 per cent. rated load, a 1 per cent increase in load without a corresponding increase in tyre pressure reduced tyre life by an average of 1.3 per cent. Correspondingly for a vehicle of 10 tons gross weight with an annual mileage life of 40,000, and using one set of tyres per year, a weight reduction of I per cent. should result in an annual saving of approximately 1 per cent, of the value of a set of tyres. In . this instance this gave a total saving of , £1.8 per annum, or 18s. per annum per , cwt. of weight saved. Moreover vehicles • running a large proportion of their mileage under partially loaded conditions, Mr. Jones added, could be expected to show more substantial savings.

A reduction in maintenance costs could also be obtained by the use of aluminium. A livestock haulier has recorded body repair costs over a number of years for both timber and aluminium bodies, showing a total saving of £110 per annum in favour, of the aluminium bodies. Correspondingly a brick company achieved a saving of £38 per annum. Under less stringent conditions, for example brewery work, savings of £16 per annum had been achieved.

For any given vehicle type savings could rarely be, recorded in respect of every cost item considered. For that reason Mr. Jones took a hypothetical case which included all such items. Relative to a drop-sided vehicle of 14 tons gross laden weight, Mr. Jones itemized the following savings by the use of an aluminium body which provided a reduction of 10 cwt. in the unladen weight:pay capacity £79, licence charges £10, maintenance £15, fuel consumption £12 and tyre costs £10: total savings £126. This indicated a net annual profit of £99 or a total profit of £990 over the life of the vehicle.

Aluminium in Engines D. DOWNS Ricardo and Company, Engineers (1927) Ltd.

THEprospects for an increased use of aluminium in vehicle engines, said Mr. Downs, depended not only on its technical advantages—light weight and better heat conductivity—but perhaps even more on a solution to the problems of cheap mass production with this material. Though these comments applied• more to the motorcar, with which Mr. Downs was principally concerned in his paper, improved production techniques would naturally encourage greater use' of light alloys in commercial vehicle engines.

Various possible ways of designing a cylinder block suitable for pressure diecasting were considered, but the best solution depended, among other things, on whether it proved possible to run an aluminium piston direct in an aluminium bore. Experiments in this direction had generally been to produce harder aluminium alloys for the bore, but bore wear itself did not seem to be the main problem. The major difficulties were during cold starting, when tardy oil flow and the washing action of unburnt fuel could lead to scuffing and scoring: it seemed that it would be essential to use chromium-plated piston rings with an aluminium bore.

Referring to present-day engines, the author pointed to ways in which aluminium pistons had contributed 'to the development of the high-speed, high-performance type, but said that in some highly . rated power units, particularly diesels, where local heat transfer was high and the fuel had a higher sulphur content, the limits of thermal loading were approached and trouble might be experienced due to carbon forming in the top ring groove. Oil cooling of the piston could usually overcome this trouble, and although at least one highly rated twostroke commercial engine had steel crowns fitted to cast-iron pistons to provide protection against burning of the crown and top land, this was an exceptional case. It was unlikely that anything other than an aluminium piston would be needed for the four-stroke road transport diesel for some time to come.

With the exception of the Gardner, no large commercial vehicle diesel used an aluminium crankcase but the fact that this engine, which had an outstanding reputation for performance and reliability, used aluminium for such a large and important structural member suggested that there was no insurmountable obstacle to even more extensive use of aluminium in commercial vehicle engines. On some, sumps, covers, manifolds and water connections were made in this material, but the policy differed widely amongst various manufacturers. There was no suggestion at this stage that crankshaft, camshaft, valves or flywheel should he made in aluminium but of the major engine parts it should be possible to make cylinder block and crankcase, cylinder head, pistons and, perhaps, con necting-rods in aluminium allo Although aluminium, was only one-thin the weight of cast-iron, bulk for bulk thickening of sections to compensate fo lower, strength and other factors mean that a head or block would probably b only halved in weight by turning to th lighter material ,

Noise, said Mr. Downs, was anothe problem with aluminium; not only wa sheer weight one of the best soun absorbers but aluminium's low elasti • modulus was also harmful in this respect. This was particularly important with diesel engines, already at a noise disadvantage compared with petrol units, though it might be possible by careful design to offset the inherent noisiness o a light structure and certainly forsuch parts as sumps, valve covers and timing cOvers, cast aluminium should be better than the " tinny " pressed steel components now common.

After dealing in detail with production methods, with special reference to pressure die-casting, Mr. Downs remarked that further development would demand close collaboration between engine designer, metallurgist and aluminium founder.

The London Transport Routemaster J. W. WICKS

London Transport Executive

THE unladen weight of the Route' master was a little more than 16,000 lb. Of this total, aluminium components included in the design weighed 3,700 lb. The reason for this high proportion of aluminium and its alloys was that the body, structure employs this material almost exclusively. The Routemaster was of chassis-less construction and steel members were used only for front and rear. sub-frames which support the mechanical units.

The requirements which influenced the design of the Routemaster were given as passenger capacity (the target was 65 seats), a rear entrance (which experience had shown was most suitable for operation in Central London), staff amenity (an ideal layout for the driver's cab and provision of a suitable position on the platform for the conductor) and passenger amenity (a good standard of seating comfort, clear destination signs and adequate interior heating).

Mr. Wicks gave details in his paper of the fabricating techniques employed in the construction of the body and the types of aluminium alloys used. He did not limit his remarks to the body construction alone and dealt briefly with the mechanical layout of the Routemaster, and explained the method of attaching the front and rear sub-frames for the mechanical components to the bottom frame assembly.

In early considerations of the problems attached to the design of the body structure, it was thought that permanently built-in longitudinal outriggers would ave to be employed to carry the front nd rear axle. It was decided later, owever, that the use of the sub-frames ally decided upon would facilitate aintenance and also reduce stress on the am n structure by utilizing pivot pins for xing each frame.

A new approach to the practice employed by L.T.E. to ensure interchangeability of parts was required for the Routemaster. All parts were manufactured to normal engineeribg accuracy. In addition to a very large number of minor sub-assembly jigs and tools used for the manufacture of parts, 17 main assembly jigs were used and, to facilitate production, care was taken to keep to sheet, angle, extruded sections and die castings where economical.

In a final summary, Mr. Wicks said that the result obtained from the development of the Routemaster had indicated that a very practical application of the use of light alloys had been made in order to achieve a positive requirement. All the original demands had been satisfied with the exception of seating capacity which was 64 instead of 65. An outstanding feature of the project, said Mr. Wicks, was that an unladen weight of 7 tons 4.5 cwt. had been achieved. The design has lent itself well to a change to 30 ft. overall length for an experimental batch of vehicles which had been accomplished by the addition of a 2-ft. 5-in, bay into the structure. This gave 72 seats and an unladen weight of 7 tons II cwt.

General Methods of Bus Design and Construction S. THOMPSON Metropolitan-Caramel! Carriage and Wagon Co., Ltd.

THE orthodox present-day method of constructing bus bodywork in this country, said Mr. Thompson, was based on a metal framework of folded, rolled or extruded material. The various parts were generally riveted together, although attention was being given to increased use of welding. Stress panels, again riveted, were fitted where necessary to the inside of the framing and often formed part of the interior finish. The exterior panels were not considered as part of the structure and were designed with ease of replacement in mind.

American practice reversed this arrangement, using the exterior panelling as a stressed part of the structure, and this system was also used on some bodies built in this country for export.

In vehicles with separate chassis, the provision of adequate transverse floorbearers was vital to the construction of a trouble-free body. Both rigid and flexible mounting of the bearer on the chassis and of the body pillars on the ends of the bearer had been tried from time to time. Mr. Thompson considered that the best type of bearer was probably one of simple channel form with rigid attachment to the pillar and insu

lated from the chassis to a limited degree by balata or similar pads.

On a vehicle of integral construction, the sides and roof had to withstand greater stresses than on a vehicle with separate chassis, and particular attention had to be paid to doorway openings to ensure that the framework was suitably reinforced.

A semi-integral construction implied the use of a chassis with outriggers to which the body sides were attached. The substantial floor-bearers used with a normal chassis were therefore replaced by a light framing solely intended to carry the floor itself. This construction, often used in association with a rear engine, was helpful in achieving a low floor height, although removal of the body from the chassis was less easy than with entirely separate units.

An all-aluminium structure was the lightest, other factors being equal, but was more expensive than a steel-framed body. Aluminium alloys were resistant to corrosion, but steel, when properly treated, could give a life of no less duration. A very satisfactory compromise was to use steel for the floor-bearers, pillars and roof canines and aluminium for longitudinal body sections and stress panels.

Aluminium sheet was generally accepted as the covering for exterior panels. Glass-fibre had become popular for certain parts of complex shape in recent times, but sheets which were flat or of single curvature and items produced in sufficient quantity to justify the use of press tools could be more economically manufactured in aluminium.

Road Tankers F. K. FARQUHARSON Shel1-114x and RP., Ltd THE use of aluminium and its alloys for road tankers dated back some 30 years, said Mr. Farquharson. A very successful 3,000-gal. tanker built in 1931, using a 1.5 per cent. manganese material, had since worked continuously, covering more than 750,000 miles and was now running behind its fourth motive unit.

in direct contrast were other pre-war road tank ventures described by the author, these all using 99.5 per cent. pure aluminium and suffering structural failures through lack of experience in using a metal which was too weak and insufficiently stiff.

This had deterred tank users from employing aluminium and until very recently steel remained unchallenged. However, a number of tanks to carry high-purity hydrogen peroxide were built for the then Ministry of Supply, successfully using 99.5 per cent. aluminium (but with 1-in.-thick shells), white a real incentive had come from the oil industry's preference for making full-load deliveries of fuel oil in maximum-gross-weight vehicles. Although weight saving would not provide as substantial a cost economy as appeared on the surface, and fuel consumption when running unladen was probably improved by no more than 0.5 m.p.g., it was possible to save some £1,500 on a maximum weight vehicle over 10 years of operation, plus the substantial scrap value of the tank material.

Aircraft experience with alloy structures had been used to good effect in designing, certain successful fuel tankers. and 4,000-gal. fuel oil tanks on rigid eight-wheeled chassis had provided 2,240 lb. of additional payload, giving a load factor of 67.3 per cent.

The present 24-ton maximum gross Vehicle weight was the main incentive for bulk liquid transporters turning to aluminium. But in considering increased payload, tank builders and vehicle operators laboured under a grave handicap since the chassis maker absorbed the largest share of the unladen weight for his own purposes. It was significant, he said, that manufacturers of heavy vehicles were not contributing ie., this discussion. This was lamentable and displayed what seemed to be a universal tack of interest in that quarter for saving weight for the operators' benefit.

In the 4,000-gal. tanks mentioned earlier, no external leaks had occurred and the design appeared satisfactory, except for failures in surge plates and bulkheads which, instead of being dished were flat, strengthened by welded. stiffeners; this combination appeared inadequate. However, many of the failures were due to welding not being up to standard.

Consideration would have to be given to dished bulkheads in future production but at least the fractures and distortion of surge plates proved that the plates were working and modifications could eliminate the few difficulties.

There was no doubt that further investigation of air suspension would be well worth while, particularly in respect of light alloy tank vehicles. Tankers operated at up to 50 per cent, of their mileage unladen and anything which improved the unladen ride would save much of the pounding and vibration that units now suffered.

Post-war experience had supported the case for the use of light alloys in tank construction and it was obvious that further exploration would be made to amend the few deficiencies of the material. There was evidence that a load factor of 71 per cent. could be achieved with a chassis-mounted tank; the frameless semi-trailer tanker should also be investigated further.

Where commodity quality was at a premium, alloy tanks were at an advantage in offering internal cleanliness at lower cost than an epoxy resin lining on a steel tank.

In conclusion. Mr. Farquharson said that to extract the uttermost advantage inherent in its light weight a, light alloy tank must be most carefully designed and equally carefully fabricated; unless the assembly was properly conceived and made, experience would be as disappointing as in the pre-war era and alloy tanks might well be set back again many years.

Aluminium for Earth Moving and Rock Hauling Equipment R. A. SMONDE Aluminum Company of Canada, Ltd.

AFTER briefly outlining the history of the use of aluminium in the construction of dump truck bodies, Mr. Esmonde described in detail the design, development and testing of the first body of this type built by his company.

Construction of this body, which appears to have had a capacity of about 20-cu.-yd., was completed in June, 1959; it was put into service a month later.

Since going into service, the prototype aluminium body has been working 24 hours a day, five days a week, making about 50 4-mile trips a day, carrying an average of 28 tons on each journey. In the two-and-a-half years operation no structural weld cracks have been found. The plug-welded, aluminium wear plate was unsatisfactory due to the liner plate lifting off the 1.25-in.-thick main floor

plate. After six months service the liner plate was replaced by wear bars. Other modifications found necessary were the use of deeper cross-members at some points, increase. of the side member thickness to withstand accidental blows from shovel teeth and the fitting of protective wear strips on the inner edge Of the top jail.

Subsequent developments included units for service in asbestos mines with capacities up to 24-cu.-yd. and some heated bodies. Many of the latter are used in Canada to prevent loads sticking in the body during the extremely cold winter temperatures which are often down to —45° C. (-50° F.). Field tests have indicated that the heat distribution through aluminium bodies is excellent, A year ago a unit was put into service on limestone work by the Canada Cement Co.: after six months satisfactory use, a second body was ordered. Other examples of the use of aluminium-body dump trucks given in the paper were two units used in a gypsum mine in Nova Scotia by Canadian Gypsum. The latest one of these was built using extruded members for the top rail, side. and underbody members. Recently the Aluminum Company of Canada, Ltd., have designed a 27-cu.-yd. aluminium body with a load capacity of 45-tons which is at present being built for the Iron Ore Company of Canada.'

In the final section of his paper Mr. Esmonde gave details of the amount and types of wear found on the aluminium bodies in service and of the aluminiummagnesium alloy chosen for the body construction. This was Alcan 6211 (N.P.6 or A.A.5456) and field tests and service performance had indicated that this alloy was generally more than adequate. As it presented a number of production problems, D54S or A.A.5083 alloys which were only slightly lower in respect of ultimate and yield strength would be used in the future.

In conclusion Mr. Esmonde said that provided aluminium suppliers and body a26

manufacturers strive continuously to improve the design of aluminium bodies for earth moving and rock hauling equipment, make sure that adequate welding is used on the construction and study operations where aluminium units are to be used, the development of the use of aluminium for off-highway bodies in Canada and in other countries will certainly increase rapidly.

Semi-trailers of Integral Construction E. W. OGLETHORPE Duramin Engineering Company THISpaper dealt with . British experience to date of integralconstruction van or van-type semitrailers. The many advantages of the use of aluminium-alloy in this field were particularly stressed.

After dealing with the development of semi-trailer vans and the economic benefits of semi-trailer operaticin, Mr. Oglethorpe discussed the advantages of the use of aluminium-alloy—including reduced running and maintenance costs and improved life—for the construction of boxvan semi-trailers.

Encouraged by the trend to this type of semi-trailer Mr. Oglethorpe's company had decided to produce a range of integrally-constructed boxvan semitrailers using high-tensile aluminiumalloys for the entire structure, including the main floor frame. No attempt was made to adapt existing North American designs, although. these were studied in the course of gathering data.

The design and development of a prototype van were described. The prototype vehicle which was completed just over two years ago measured 25 ft. 5 in. inside length x 7 ft. 6 in. overall width and 7 ft. 6 in. height. Unladen and without spare wheel or carrier the unit weighed just over 2 tons • 16.5 cwt., of which 1 ton 5 cwt. was represented by the attached running gear. Subsequent modifications have reduced the body weight by a further 1 to 2 cwt.

Extensive trials of the prototype included tests on the M.I.R.A. track at Nuneaton. The semi-trailer suffered no structural damage, which proved the astonishing resilience of aluminium-alloy in severe conditions.

In describing other integral semitrailer vans made in this country Mr. Oglethorpe said that at least four versions had been introduced in the past three years. Three were built • of aluminium throughout, but so far as was known these were not produced in any quantity. The fourth model of which several hundreds we're in service drew its inspiration more directly from North American practice and employed a welded-steel main floor frame in conjunction with an aluminium-alloy superstructure.

A comprehensive range of designs was now available from one or other of the leading manufacturers and examples of how basic designs could be varied to suit particular requirements were given. Speaking of the future, Mr. Oglethorpe said that the indications were that integral construction would play an increasingly important role in semi-trailer design. A further impetus to the development of such units would be given on Britain's entry into the Common Market.

Aluminium in Municipal Transport D. FOSTER Dennis Bros., Ltd.

THE main uses for aluminium in the field covered by this paper were given as refuse collector bodies, fire-engine bodywork, ambulances, street orderly trucks, paper salvage trailers and coachbuilt constructions generally. Aluminium alloys were used both as extrusions and as castings as well as for exterior and interior panelling on these vehicles to improve payload to gross vehicle weight ratios, for appearance, for corrosion resistance and wherever low weight was essential.

The main problems with refuse bodies were given as corrosion, abrasion, electrolytic and stresses brought about by compression loading. The use of aluminium in conjunction with suitable design and adequate maintenance overcame these problems.

The effects of sea water on vehicles with polished aluminium bodywork which were exported by sea could be troublesome and although deck stowage was accepted in very rare cases only, Mr. Foster said that as a precaution against attack, the whole body was sprayed with a protective coating such as Ensis fluid which could be removed easily after the voyage. It was pointed out that it appeared that a fair amount of direct contact with sea-water was required for much harm to be done. Many coastal towns had had refuse collectors with unpainted aluminium bodies in service for many years and there was little evidence of ill effects from sea breezes.

Though considered to be somewhat outside the scope of the paper, Mr. Foster made reference to the large containers used for handling refuse in bulk. An example of such a vehicle having a power hoist to lift and discharge containers into its body was given. The general practice bad been to manufacture these containers in steel, galvanized after fabrication, but the use of aluminium had obvious advantages. Originally these containers were riveted but they were now tungsten-arc welded, the base being a suitable extrusion, butt-welded to form a ring.

In concluding his paper Mr. Foster said that because municipal transport had such a variety of specialized vehicles it was impossible to cover all the applications of aluminium and its alloys. Developments in the field were 'quite rapid because of the flexibility of production, and one of the chief ways in which further advances were expected to be made was in the use of aluminium castings.