AT THE HEART OF THE ROAD TRANSPORT INDUSTRY.

Call our Sales Team on 0208 912 2120

We are used to trucks looking pretty much alike and

23rd December 1999
Page 50
Page 51
Page 52
Page 53
Page 50, 23rd December 1999 — We are used to trucks looking pretty much alike and
Close
Noticed an error?
If you've noticed an error in this article please click here to report it so we can fix it.

Which of the following most accurately describes the problem?

having similar features under the skin, but in the early years of the 20th century there was a bewildering variety of vehicles on the road. Few of these live on—but who can say that some of them won't come back?

Peter Lawton trawls through the specs.

petrol, steam and electrically-powered vehicles were all on sale by the time Commercial Motor went to press for the first time in 1905. Although Rudolph Diesel patented an engine in 1892, it would be more than 40 years before his compression-ignition system caught on, and decades more before "oil engines" became the norm in commercial vehicles.

Commercial Motor often debated the relative virtues of steam, petrol, electrical and petrolelectric systems with an early editorial favouring the last as the area "exhibiting the greatest possibilities for development".

In the first issue petrol featured in a twopage spread detailing its advantages over steam for powering fire engines. With response times critical, it was felt petrol was by far the most appropriate fuel. But not everyone agreed, including the managing director of Pickfords who felt the risk of fire from petrol left steam as the only way forward. Perhaps this risk of fire is the reason that a steam tractor was used to haul a load of petroleum (see picture, next spread).

The arguments continued, with Commercial Motor backing no horse in particular. We could see no reason why combustion engines should come to dominate the entire field of commercial vehi des, but still felt the need to defend steam in 1907, telling readers about the latest advances with superheated steam and flash boilers.

In general the internal combustion engine was confined to use on omnibuses, charabancs and lighter loads, while the heftier jobs remained with steam tractors, turned out across the country by manufacturers such as Mann, Coulthard and Foden,

Gearboxes were generally confined to a maximum of four speeds, while braking had to be planned as most vehicles had only rear wheel brakes. Electrical and hybrid vehicles were much in evidence as light trucks and buses, but users would eventually complain of limited range and power.

Although most vehicles had chain final drive arrangements to the rear wheels, there was also interest at this time in live axles, both front and rear. Power was distributed to the axles by means of bevels, worm or spur gears. CM avoided the controversy of deciding which system was best, but the bevel appears to have won.

The edition of 2,6 January 1911 was a landmark issue; we ran a piece with the headline. "Diesel Oil Engine for Motorbuses—A Striking Development of a Highly Efficient Internal Combustion Engine".

It read: "Of late years the diesel oil engine has come very much to the front for all purposes; it is now rapidly replacing steam engines, and in many cases gas engines, being by far the most economical prime mover now manufactured and probably one of the most reliable."

Why we should confine its use to the motor bus is unclear, but we told readers that engines were being built in France and Germany by companies like Maschinenfabrik Augsburg-Nurnberg (MAN). Stationary engines and those for use in the marine field were already well established, we said, before describing the engine's four-stroke action. Incidentally, MAN is still making advertising copy of the claim that it built the first diesel.

One drawback of the new breed of engines was their weight and size—described at the time as "unduly large"—and their limited power. Other drawbacks to be ironed out included the starting of the engine and methods of injecting the fuel. "Large engines are started up by compressed air stored in cast steel bottles whilst a further vessel is needed for the fuel injection," we wrote.

Given the low cost of diesel at the time—we quoted a figure of 45 shillings (p2.25) a ton— economy could only be called "remarkable".

The article appeared next to another on an internal combustion innovation which failed the test of time. This used finely broken up bituminous coal. We said: "Very promising. Whether it will ever be practically applied to motor vehicles, however, is a question to which we hold an open mind."

Despite the ringing endorsement we gave diesel, steam was to survive for a good many years yet, with manufacturers reporting they had never been busier—Foden even produced a 10-page booklet dealing with the economical repair of steamers. Interest in the compression-ignition engine was slow to pick up in England in particular and there is little mention of it in the pages of Commercial Motor until 1916; then we reminded readers of its advantages, saying that sooner or later it would have to be adopted.

Meanwhile, in 1913 we ran a piece called the "The Coming of the Four Wheel Drive", in which we recommended English manufacturers keep an eye on the technology being developed by the French army. Four-wheel drive was a by-product of the "great reliability trials" of the Great War which made and broke a good many reputations. Four-wheel drive had won through as a future contender and in August 1915 CM carried extensive details of an American five-tonner. With live axles front

and rear, the design allowed front, rear or allwheel drive though dog clutches. While the differential lock was necessary in the Great War, we wondered whether it was necessary for commercial vehicles in peace time.

War time also meant fuel shortages—petrol in particular—and attention was focused on steam and gas, with vans carrying huge balloons of town gas on their roofs.

But "more progress needs to be made in adopting diesel engines", we said in 1916, and again described the system. Because of the heat needed to fire up on oil, we predicted that a combination engine using petrol until the required heat was reached would be the most likely design to succeed rather than the hot bulb type.

We said: "It seems probable that if an engine is to be developed suitable for use on commercial vehicles, it will not run on the pure diesel cycle, but probably some sort of engine will be evolved that can be started as an ordinary petrol engine, and afterwards changed over to running on diesel or the hot-bulb system, or some combination of these methods."

The difficulties were great, we thought, but "the proposition is far from hopeless". The great Ettore Bugatti made a patent application for a petrolcum-diesel engine in 1924 but this was never to be. With separate cylinders for spark and compression-ignition opera tion, perhaps this was just as well.

The popularity of electrically powered vehicles was beginning to wane as users realised their shortcomings in terms of power, range and speed. Edison Accumulators stood their ground and defended the technologies but it was only a matter of time before they were relegated.

A "very great step forward" for diesel was hailed in 1919. Because of their

weight and slow speed, they had lived in the shadow of petrol engines, but a new diesel called the Hvid cut the weight penalty to just ro%. By spreading ignition over a longer time at lower pressure than normal, cylinders no longer had to be as reinforced as before, with consequent savings in weight.

By 1920, air cooling was touted as the next likely trend in lorry construction, and lives on in Deutz engines to this day.

Steam powered on and was much in evidence at the 1924 Business Vehicles of the British Empire Show at Wembley in April, 1924. Foden and Atkinson both showed 0 steamers, admittedly alongside a six-cylinder Halley petrol engine.

Six-wheeled vehicles, mainly buses but some automobiles, were also appearing at this stage, most with live axles and worm or bevel gears—but others were still chain-driven.

Braking had by now been added to the front wheels. Disc brakes were still a long way off for use on truck wheels, and were long avoided because of disc warping. But in 1924 we unveiled an American La France design for a driveshaft-mounted brake disc, set between two asbestos-faced discs.

Eventually it was required by law that a motor vehicle had to have two separate brakes. It was ruled in the High Court that the engine-braking action of a petrol engine did not count, because the action could be interrupted by the application of the clutch pedal. Although the same ruling was not applied to steam engines, their days were soon to end.

By 1926 Benz had developed a two-cylinder diesel giving 3ohp at 800 rpm using a pre-combustion chamber. Now there was no turning back for compression ignition. Editorials charted the progress of the technology in France and Germany, but there was still little interest from the normally inventive British. Daimler-Benz, Peugeot and MAN featured regularly, and in June 1928 we felt compelled to write: "It seems strange that the engineers of a manufacturing country such as ours have not devoted more time to the development of the diesel engine.

"There would appear to be great potential for this type of power unit, and there does not seem to be any really great difficulty in constructing a satisfactory engine now that a suitable fuel injecting pump is available."

This unit in question was made by Bosch and became available in England in 1927. The pump was the most important development so far, and now diesel fuel injection is almost synonymous with Bosch. Although diesels for lighter vehicles were still a little way off, the basics of the compression-ignition engine were to change little over the next Go years. Future developments were more a matter of detail: refinements and improvements to fuel delivery systems, materials, pressures and cooling.

Foden famously dung to steam, launching new models and building steam engines into the 193 05. The unwillingness to embrace diesel caused a rift in the Foden family and ER Foden left to start his own company, ERF.

The economic realities could not be avoided by Foden which started building diesel-powered vehicles in 1931—CM tested a rapid sixtonner with a Gardner engine in 1932 (see box). The last steamer was built in the same year as diesel took hold and all but eliminated petrol and electric vehicles from commercial use.

CM wrote: "In the firm's opinion, there is no better proposition on the road for goods transport than the oil-engined vehicle. It gives fuel economy, quick acceleration, cleanliness, and can be driven for hours without the dizziness so often occasioned by the fumes of a petrol lorry." However, even in 1936 a new Albion to-tonner was being offered with an Albion petrol or Gardner diesel engine.

Pneumatic tyres were now more reliable, materials were becoming lighter and drivers were spoilt by range-change boxes.

There were many ideas for exploiting engine braking: as early as 1918 we discussed Saurer's system of shifting the camshaft phase by 90°.

Service brakes saw further improvement in the move from hefty cable operation to hydraulic systems, and combinations of rod, cable and Lockheed hydraulic units were corn

monplace in the thirties: brake compensation became an issue and ingenious (or just plain complicated) devices appeared, such as the Bendix Auto Control. During the late twenties, air or vacuum-operated power assistance had become available, Clayton Dewandre being the most common make. Theed even made a retro-fitting kit to add vacuum assistance to a conventional system.

Disc-against-disc brake designs emerged in

the forties, but there appeared to be a breakthrough in 1949 when American firm Crosley developed the Hydradisc. This used a single cast iron disc against which were damped two small friction plates each the size of a silver dollar". It was claimed that the large exposed area of the disc gave excellent cooling. "We have often wondered why such a brake has not been developed here for commercial vehicles. It seems simple and effective with few wearing parts and, consequently, reduced maintenance and less liability to chatter," said CM.

In 1957 four disc-brake applications were detailed, including one from Goodyear, and in November we announced that "air-operated brakes, together with an independent transmission hand brake, are to be fitted to all Foden vehides for the home and overseas markets". Five years later, Dunlop offered its Mark IX disc brake for fitting to air, vacuum or hydraulic systems.

Anti-skid or anti-lock brake systems made many appearances through the years: in 1937 we featured an anti-skid device for vacuum-assisted brakes, which relied on a centrifugally operated "leak port" which opened when a wheel stopped rotating. A similar, but electrically operated device for hydraulic brakes appeared in 1942. Twenty years later, Dunlop pioneered a practical system, and we said: "Although the system is too costly for application to production vehides it provides a technical standard by which conventional systems can be judged."

Synchromesh gearboxes did not become common in trucks until the eighties (and are still very much the exception in the US), although ZF first built one in the late twenties and Alvis was fitting synchromesh to sports cars in 1933. In 1925 Renault demonstrated a hydraulic clutch which changed gear when torque produced was more than resisting torque. Twelve years later, Maybach of Germany patented a pneumatic device which controlled engine speed and a transmission brake, permitting synchronised shifting in a heavy truck—but this idea did not progress much until ZF introduced an electronic equivalent (AS-Tronic) three years ago.

Automatics are longer-established: Daimler and Leyland buses were being fitted with fluid flywheels in the thirties and fully automatic boxes were available soon after. In 1941 CM covered a patent application from General Motors for an automatic gearbox using a direct drive and a fluid torque converter. We reported: "Pneumatic servo cylinders are controlled by electrically operated governor-controlled valves. Heavy pressure on the throttle will result in a down-change and switches are provided to assume manual control."

But we remained to be convinced and in 1952, we wrote: "Whilst the problem of providing an automatic transmission system for cars has been solved, the complete solution for commercial vehicles is still the subject of intensive research. Any new transmission would have a difficult job to equal or exceed the performance of the present sliding gear system."

And half a century later, plenty of operators would still agree.

Many ideas that were around at the beginning of the century are once again in the spotlight-a case in point was described in the second issue of Commercial Meter (23 March 1905). Dougills offered a Fhp van priced at 145 guineas (£152.25), featuring an early form of continuously variable transmission: "Upon the engine shaft is a large cast Iron driving disc which comes into contact with a disc or discs at right angles thereto, composed of compressed leather, "The shaft carrying the driven discs is parallel to the driving disc, and swings on hanging brackets. From this shaft the drive is conveyed to the rear live axle by a roller chain, this chain running inside the frame. The frictional contact between the driving and driven discs is maintained by adjustable springs anchored to the vehicle framing, "The driven disc can, by means of a convenient level, be carried along its own shaft so as to be in contact with any portion of the driving disc (always in a horizontal plane) from either periphery to the centre. The gear ratio is usually arranged to give the maximum of 5 or 6 to 1."

Engine progress

1906

Vehoe, 40hp Critchley-Norris 4x2 omnibus Ertrie Water-cooled, naturally-aspirated patrol engine, with Simms-Bosch low

tension magneto ignition.

Cylinders: tour, in line.

Bore x stroke: 435in x Bin (121mm x 152mm).

Capacity: 5,953cc

Compression ratio: 5.11 Power output: 30hp (22kW) at BOOrpm.

Torque: 1971bft (267f1m) at BOOrpm.

Transmission: Crftchley-Norris four-speed constant-mesh gearbox.

Clutch: Leather-faced cone.

Flnai drive: Cearbox-mountod differential driving rear wheels via twin open chains.

With a low operating speed and low compression ratio, this petrol unit claimed only 30hp from six litres and a top speed of just 12mph.

1919

Vehicle: Daimler 2-3-ton 4x2 lorry Gross vehicle weight 5.59 tonnes.

Engine: Daintier sleeve-valve naturally-aspirated petrol

engine.

Cylinders: Four, in line.

Bores stroke: 95x 140mm.

Capacity: 3,969cc.

Power output: 30hp (22kW) at 1,000rpm.

Torque: 158Ibft (214Hm) at 1,000rpm.

Transmission: Daimler four-speed constant-mesh gearbox.

Clutch: Fabric-lined cone.

Final drive: Overhead-worm axle.

Maximum geared speed:14.5mph.

Power-to-weight ratio: 5.4hp/tonne.

Petrol was still king, but speeds and outputs had increased

steadily, while Knight-type sleeve valves made this engine

quieter. Final drive was now via a geared axle.

1932

Vehicle: Foden oil-engined 6-7-ton 4x2 lorry

Gross vehicle weight: 11.85 tonnes.

Engine: Gardner 61.W naturally aspirated direct-injection

diesel.

Cylinders: Six, in line.

Bore x strokr 108 x 152mm.

Capacity: 8,369cc.

Compression ratio: 13:1.

Power output: 102hp (76kW) at 1,700rpm.

Peak torque: 348Ibft (472Nm) at 1,10Orpm.

Transmission: Foden eight-speed range-change constant-mesh

gearbox.

Clutch: Single dry plate.

Final drive: Overhead-worm axle.

Maximum geared speed: 37rnph.

Power-to-weight ratio: 8.6hp/tonne.

Powering one of Foden's first diesels, this high-output Gardner "oil engine" featured a decompressor for hand starting.

1949

Vehicle: Atkinson L644 4x2 goods chassis

Gross vehicle weight: 9.71 tonnes.

Engine: Gardner 4LK naturally aspirated direct

Injection diesel.

Cylinders: Four, In line.

Bores stroke: 95 x 133mm.

Capacity: 3,801cc.

Power output. 57hp (43kW) at 2100rpm.

Peak torque: 1611bft (218Nm) at 1100rom.

Transmission: David Brown 542 five-speed constant

mesh gearbox.

Final drive: Overhead-worm axle, ratio 6.5:1.

Maximum geared speec 44mph.

Power-to-weipht ratio: 5.9hp/tonne.

By now electric starting was common, the operating speed of this smaller diesel was higher, and a five speed gearbox was offered,

1965

Vehicle: Albion Super Clydesdale four-wheeler.

Gross veh, 16.47 tonnes.

Engine: Leyland 0.400 naturally-aspirated direct injection diesel.

Cylinders: Six, in line.

Bore x stroke: 107 x 121mm.

Capacity: 6,532cc.

Compression 16:1.

Power output: 125hp (93kW) at 2,400rpm. Peak torque: 30016ft (407Nm) at 1.600rpm. Transmission: Albion six-speed constant-mesh Gearbox.

Final drive: Albion double-reduction axle, ratio 6.93:1. Maximum geared speed: 52mph.

Power-to-weight ratio: 7.6hp/tonne.

More gears, more power, higher compression ratios, shorter piston stroke and higher speeds diesel technology progressed steadily.

1982

Vehicle: Ford Cargo 1615 4x2 rigid

Gross vehicle weight:16.22 tonnes.

Engine: Ford 150 direct-injection turbo-diesel.

Cylinders; Six, in line.

Bores stroke:105 x 115mm.

Capacity: 5,950cc.

Compression rui.'1.t 15.5:1.

Power output:148hp (110k1V) at 2,400rpm.

Peak torque: 355Ibft (481Nm) at 1,700rpm.

Transmission: Ford 8-570-$ eight-speed range-change synchromesh gearbox.

Final drive: Eaton single-reduction spiral-bevel axle, ratio 4.88:1.

Maximum geared speed:60mph.

Power-to-weight ratio:91hp/tonne.

Turbocharging was a significant advance: engine output grew, fuel efficiency grew even more, and power-to-weight ratios went up considerably.

1999

Vehicle: Volvo FM? 250 4x2 rigid

Gross vehicle weight:18.0 tonnes.

Engine: Volvo D7C charge-cooled direct-injection

turbo-diesel.

Cylinders: Six, In line.

Bore x sti• • 107 x 135mm. Capacity 7,284cc.

Compression r 19.5:1.

Power output. 247hp (184kW) at 2,200rpm. Peak torque: 775Ibft (1.0506m) at 1,100-1,400rpm. Transmission: Volvo R1400 eight-speed rangechange synchromesh gearbox.

Final drive: Volvo single-reduction hypoid axle, ratio 3.111:1.

Maximum geared speed: 73mph.

Power-to-weight ratio: 131hp/tonne.

Now charge-cooling, electronic control and improved materials have again transformed truck performance and they are easier to drive than ever.


comments powered by Disqus