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A Show to Remember. . By P. G. TUCKER

Interesting Features of Many New Models as Revealed by an Examination of Vehicle Exhibits at Earls Court

THE 1950 International Commercial Motor Transport Exhibition, the 15th of the series, will be remembered not only for the high percentage of new models on view, but for the fact that a number of leading makers has broken away from conventional practice by adopting an underfloor position for the power unit. In the case of the Foden passenger chassis, the engine is mounted vertically at the rear.

That an underfloor-engined model would eventually figure in most makers' programmes was inevitable, and whatever prejudice operators may have nurtured against the type, 'should be completely dispelled now that such concerns as A.E.C., Leyland, Dennis, Guy, Sentinel, Atkinson, Crossley, Maudslay and Commer are offering such models.

It may be of interest to recall that in 1937, TillingStevens, Ltd., created something of a sensation with a flat-engined, six-wheeled chassis in which the power unit was mounted amidships below frame level. This model also incorporated many interesting features, such as a seven-speed, vacuum-operated gearbox, and independent suspension for the wheels of the rear bogie. Possibly the industry was not ready for such a breakaway from conventional practice but, whatever the reason, the model was eventually dropped.

On the other hand, the Sentinel concern has persisted with its underfloor-engine policy and both goods and passenger chassis of this type have been produced for a number of years.

On this and following pages is given a brief review of those vehicles which have been introduced during the past few months, a number of which is entirely new and is being revealed for the first time at Earls Court._

Goods Vehicles

nEALING first with the goods vehicles, the Seddon " Mark 74 represents the smallest oil-engined model in series production in this country. It is a 3-tonner, powered by a .Perkins P4 oil engine. This unit, of 3.14 litres capacity, develops 50 b.h.p. at 2,40 r.p.m., the maximum torque being 123 lb./ft. at 1,000 r.p.m. The design of the chassis is quite straightforward, the specification including a four-speed gearbox, hypoidgear rear axle and Girlirig brakes. A road test of this machine was described in "The Commercial Motor" for August 4

Another model new to the Seddon range is the Mark 8 9-ft. wheelbase tractor, with automatic coupling for use with Scammell semi-trailers This chassis has a Perkins P6, 79 b.h.p. oil engine and a two-speed rear axle. The tractor weighs 2 tons 13 cwt., the payload of the trailer being 10 tons The new Big Bedford marks the entry of this make of vehicle to the 7-ton class, as previous models have not exceeded 5-ton payload capacity. It has a 4.92litre petrol engine developing a maximum of 110 b.h.p. at 3,200 r.p.m. Dry cylinder-liners are used, and these can be withdrawn and replaced without the use of special tools. • In the new gearbox, synchromesh engagement of top, third and second gears is provided, the third and second gear-trains being of the singlehelical, constant-mesa type. Hypoid gears are used in the back axle.

The steering column is connected to the steering gearbox by a universal joint, the steering-column tube at its upper end being carried in a rubber-bushed bracket attached to the instrument panel.. Improvements are noticeable in the design of the cab, which now has corner .lights in addition to a centre back light of generous area A double-skin engine cowl provides a channel through which air is drawn by suction from the engine fan, the air inlet being arranged behind the left-hand louvre at the bottom of the front panel of the cab.

Although the Dennis Centaur is not new in name, it appears in a completely new form, its specification being based on that of the Dennis Falcon passenger chassis. Its oil engine develops 75 b.h.p. at 2,000 r.p.m.; a torque of 222 lb./ft is produced at 1,100 r.p.m. The general specification includes a five-speed gearbox and a two-speed rear axle. With a gross vehicle weight of about 101 tons,the maximum payload capacity is 7 tons.

The Dennis F8 fire-engine is notable for its small overall dimensions, the wheelbase being 10 ft. and the width 6 ft 6 ins. It has been introduced to meet the need for, a fire-fighting vehicle that can, if necessary, operate in restricted areas. All the personnel are able to travel within the body, the complete appliance with a 250-gallon first-aid supply of water weighing under 5 tons.

Sentinel (Shrewsbury), Ltd., has new models with underfloor engines. These are rigid six-wheelers, the main differences between them being that the light model has a trailing-bogie axle, four-cylindered oil engine and live-speed gearbox, whereas the heavy model drives on both bogie axles, has a six-cylindered oil engine and incorporates an auxiliary gearbox in conjunction with a five-speed main unit.

Two new models are staged on the Morris Commercial stand, these being 3and 5-tonners in which a six-cylindered overhead-valve petrol engine is used for the first time by this maker. The capacity of the new power unit is 4.25 litres, the output, as installed in the 5-tonner, being 100 b.h.p. at 3,200 r.p.m. A derated version is employed in the 3-tonner, the output in this case being 70 b.h.p. at 2,600 r.p.m. The unit has an R.A.C. rating of 28.81 h.p.

The insulated, all-steel driver's cab embodies an air-circulatory system providing a constant supply of fresh air via elongated vents in the front edge of the cab roof. Another feature to note is the large built-in " well" step to the cab. Room in the cab is not encroached upon by any part of the engine, so that the driver and two passengers can be comfortably accommodated.

On the Morris stand are examples of the new Morris Cowley 10-cwt. chassis which was introduced early this year. .

This vehicle incorporates a similar power unit and a number of other components, as used in the Oxford private car. The four-cylindered, 1.5-litre side-valve engine has an R.A.C. rating of 13.4 h.p. and develops a maximum of 40.5 b.h.p. at 4,000 r.o.m. The suspension at the front end is by torsion bars, with .control by double-acting hydraulic dampers. The drive is taken through a dry-plate clutch of 8-in, diameter to a four-speed synchromesh gearbox, and the semifloating rear axle has hypoid-gear drive.

114 Whilst the basic design of the Karrier models shown remains the same, the 2-ton and 4-ton machines have been given a modern frontal appearance with a redesigned steel cab, which also provides increased comfort and improved visibility. Improvements have also been effected in the frame-construction, and the 48 b.h.p. engine installed now has chromium-finished cylinder bores. These improved features also apply to the Bantam 4-5-ton tractor-trailer machine.

Earlier in the year, Albion Motors, Ltd., introduced a new range of hea‘y-duty goods vehicles which have been in production since last April. The main differences between these and the CX class lie in the adoption of compressed-air braking, a five-speed gearbox, engine bearings of increased area and a heavier timing chain. The HD.53, which is exhibited, is representative of this new mark. As a solo machine, the permissible gross laden weight is 12 tons, or as a.tractor-trailer combina

tion, 22 tons. This chassis is powered by the Albion 9.9-litre, six-cylindered oil engine, its five-speed gearbox being of the constant-mesh type. The HD.57 chassis is also on view.

The Foden FG.8/15 overseas chassis, which is shown for the first time, has a close-ratio four-speed gearbox, to which is bolted an auxiliary epicyclic gearbox enabling eight forward speeds and two reverse ratios to be obtained. The design is such that a gear can be preselected through the epicyclic unit, the change being made by depressing the clutch pedal. This chassis is powered by the Gardner 8LW oil engine, which produces 150 b.h.p. at 1,700 r.p.m.

Employing the Gardner 8LW oil engine which normally develops a maximum of 150 b.h.p., Atkinson Lorries (1933), Ltd., shows a new six-wheeler designed for overseas operation. As exhibited, the engine is in derated form with an output of 128 b.h.p., as this particular vehicle, built for use 'in South Africa, will be operated at 2,000 ft. above sea level. It is intended for a gross tractor-trailer load of up to 50 tons. The specification includes a five-speed gearbox mounted at an angle to give a straightthrough run for the gear-change shaft, and Kirkitall doUble-reduction axles and hub gear in the bogie assembly, giving an overall 'reduction of 10.55 to 1.

In keeping with the general character of this chassis, the parallel and straight -side-members of the frame-are of generous dimensions, being 11 ins, deep, with 3-in flanges and of f-in. gauge steel. Rearward of the gearbox, the frame is braced by five substantial crossinernbers, a bridge-piece linking the side members at a

point in line with the flywheel housing. An enginedriven compressor sApplies the Clayton Dewandre airpressure braking system, 5-in.-diameter cylinders being fitted on the front wheels, whilst those at the rear are 6 ins, in diameter.

New to the Dodge range is an 8-ton tractor incorporating Scammell automatic coupling gear. Based on the maker's short-wheell-ase models, it is powered by the Perkins P6 oil engine, and has a five-speed gearbox and two-speed rear axle The chassis frame has, of course, been redesigned to accommodate the coupling gear.

Powered by a Meadows 6DC 630 oil engine, the Scammell six-wheeled six-wheel-drive chassis represents an addition to this maker's range of specialized types. Double-reduction, spiral-bevel and epicyclic gearing is used in the fully floating front axle, whilst the wormdriven rear axle drives the wheels through a train of gears. Both braking and steering are assisted by compressed air. Suspension at the front is by a transverse leaf spring so mounted as to permit of free articulation of the axle. At the rear, long semi-elliptic springs are employed, the cases housing the gear trains also doing duty as rocking beams.

The. most powerful tractor in Earls Court is the Thornycroft Mighty Antar, powered by a Rover Meteorite 250 b.h.p., 18-litre oil engine. This huge machine; with a maximum gross-laden-weight rating of

up to 100 tons, has a four-speed main gearbox and a three-speed auxiliary box, double-reduction bogie axles, and power-assisted steering, braking and clutch actuation employing Clayton Dewandre equipment.

In a vehicle of this size and power, the design of the rear bogie presented a number of new problems to Kirkstall Forge Engineering, Ltd., maker of this unit. The design was based on a ground-reaction load of 36 tons on 14.00 by 24-in, twin tyres. The overall width of the bogie is 10 ft. 3 ins., and the angle of articulation allows for the simultaneous rise of diagonally positioned wheels to the extent of 15 ins. The tractor shown is one of a number being built for operation in Iraq.

At the other end of the scale is the Thornycroft Nippy 3-tonner, fitted with the maker's six-cylindered, 4.14litre oil engine. This unit is a direct-injection version of that employed in earlier Sturdy chassis. The Nippy hitherto has been available with only a four-cylindered petrol engine, and whilst the b.h.p. of the two engines is roughly the same, the torque of the oiler is higher.

Of the lighter types of vehicle there is the Helecs Intruder battery-electric, a 25-cwt. delivery van. The control unit comprises a four-speed contactor assembly, a compensated differential link controller (the subject of a recent patent), and a five-bank resistance unit.

The battery-electric vehicle shown by Tilling Stevens, Ltd., is a new model. It is a 5-ton low-loader, the motor fitted being of 17 h.p. It has an under-slung, worm-driven axle and Lockheed continuous-flow braking system. This model is complementary to the maker's existing straight-frame 5-tanner, a common feature of both models being the rotary solenoid-operated, quickbreak controller gear with a damper time-delay arrangement -between the pedal and controller

Recently introduced into the Vulcan range is a 7tonner which was fully described in "The Commercial Motor" for August 18. This new chassis is powered by a Gardner 4LW oil engine, which is suspended on rubber-bushed links at the forward end and Silentbloc units at the rear end. The gearbox, which was designed and produced in the maker's Maidstone works, is in light alloy. It provides five forward ratios with constantmesh gears for third and fourth; first and second are of sliding-spur design, with the direct-drive top ratio engaged by a sliding dog. A two-piece, open propeller shaft conveys the drive to a hypoid-gear rear axle of Tilling-Stevens design.

Universal Power Drives, Ltd., shows an example of the Unipower Hannibal four-wheel-drive tractor specifically designed for forestry work. The Hannibal is a more powerful version of the Forester, which is also

shown. It can haul a gross trailer load of up to 15 tons, or it can give a sustained pull of over 28 tons through the medium of its winch gear. The substantial land anchor at the rear prevents the vehicle rearing up when heavy timber is being roped. The main gearbox provides five forward speeds, the auxiliary gearbox fitted making 10 forward speeds available. Spiral-bevel gear is used in the front and rear axles, Rzeppa constantvelocity high-angle joints being provided at the driving and steering ends of the front axle.

The Unipower 4 by 4 general-purpose, cross-country chassis is also new to the maker's range of specialpurpose vehicles. In this case, a Perkins P6 oil engine is installed, and the Moss gearbox provides five forward speeds, 10 forward speeds being made available by a two-speed transfer box.

Driven and Steered on All Wheels

There are many points of interest in the Latil 120 b.h.p. tractor, in that it incorporates such features as four-wheel-drive, four-wheel power-assisted steering, and a full range of ratios in reverse. It has two steering wheels and duplicated controls, so that it can be driven forward and in reverse with equal facility. The engine has a capacity of 8.35 litres, its maximum b.h.p. being developed at 1,850 r.p.m. From the transfer box the drive is taken to frame-mounted differentials, from which mechanically jointed shafts convey the power to internally toothed rings in the wheels via straight toothed pinions Brake application and steering are assisted by compressed air at a normal operating pressure of 80 lb. per sq. in.

The Electrojan strikes a new note in battery-electric vehicles in that, with the exception of the power unit, it follows the design of the Trojan petrol-engined machine. Not only does this assist production, but it means that a driver can change from one type of vehicle to another with every confidence, as the major controls are identical. Both the clutch and gearbox are retained and their use means the smoothest possible get-away; a change-down on a severe gradient reduces the demand on the battery.

The Prairie estate car shown by Renault. Ltd., is new to this country. It is powered by a 17.9 h.p. petrol engine, as used in the Renaelt private car. The design of the chassis is straightforward and includes a fourspeed gearbox and hydraulic braking. It has a payload rating of 15 cwt., or will carry six-seven passengers.

With its two-cylindered flat engine, which drives to the front wheels, the Dyna-Panhard presents a conventional external appearance. Of 9-cwt. payload rating, a claim is made to a fuel consumption at the rate of 56 m.p.g. Independent front-wheel suspension and hydraulically operated brakes figure in the specification.

Passenger Vehicles

HE highlight of the Show is the number of under' floor-engined passenger chassis, six makers having entered this field since the 1948 Exhibition.

The Foden represents a complete breakaway from conventional practice, in that the engine is mounted transversely at the rear. As exhibited, the maker's 4.1-litre, two-stroke engine is installed vertically, this unit, with clutch and gearbox, being flexibly suspended on the three-point principle. Interposed between the clutch and the gearbox, the latter being mounted at right angles to the crankshaft axis, are spiral-bevel gears which take the drive. From the gearbox a short, universally jointed shaft conveys the drive to the wormdriven rear axle.

Both the Crossley and Maudslay concerns, members of the A.C.V. group of companies, show underfloor engined chassis which have many features in common with the A.E.C. Regal Mark IV. The A.E.C. 9.6-litre oil engine is used, but in the case of the Crossley a single-plate friction clutch and synchromesh four-speed gearbox are incorporated, whereas the Maudslay has a fluid coupling and four-speed preselective gearbox.

Utilizing the Gardner 6HLW engine, Atkinson Lorries (1933), Ltd., shows a new four-wheeled passenger chassis in which the engine is mounted amidships.

The Dennis Dominant underfloor-engined passenger chassis is powered by the maker's 7.6-litre oil engine, which is a modified version of the Dennis 0.6. The unit is mounted amidships, and in unit construction with it is a four-speed, semi-automatic gearbox made under licence from Hobbs Transmission, Ltd. This unit operates on the planetary principle, the changes of ratio being controlled by wet-plate clutches and torque reaction brakes. So smooth is the take-up that changes of gear can be made, either up or down, with the throttle fully open. The complete vehicle shown is the home model, the export version being exhibited in chassis form. The latter has a supercharged engine, in which form 130 b.h.p. is produced, as against the normal 100 b.h.p.

The 44-seater single-decker bus shown by Sentinel (Shrewsbury), Ltd., is an 8-ft.-wide export vehicle employing a 9.1-litre six-cylindered, underfloor engine, This unit develops 135 b.h.p. at 2,000 r p.m. A lightalloy body is used, the main members of which form an integral part of the chassis frame.

Of the trolleybus chassis shown on the Sunbeam stand, model MF2R represents a recent addition to the maker's range. It is of the two-axled type, built for overseas operation. A feature in the construction is its rear-mounted traction motor. The chassis was designed for single-deck bodies to carry 40 seated and 20 standing passengers.

On the Tillings-Stevens stand can be seen an Express Mark II passenger chassis with Meadows 80 b.h.p. oil engine. This model has a five-speed gearbox and hypoid rear axle.

Back in the Passenger Field Dodge Brothers (Britain), Ltd., has re-entered the passenger field with a 15-ft. 10-in. wheelbase 32-seater, chassis with a drop extension at the rear of the frame. This model, which for the present is available only for export, employs the Perkins P6 oil engine, which develops 79 b.h.p. at its governed speed, and the transmission includes a five-speed direct-drive-top gearbox and a hypoid drive to the rear axle.

The Leyland Royal Tiger chassis, 620 of which have been ordered for Cuba, is another of the horizontal underfloor-engined chassis. A representative model of the range, which comprises 16 underfloor-engined models of varying lengths, widths and positions of controls, is shown, this being a 17-ft. 6-in. wheelbase. 8-ft.-wide chassis for an overall body length of 31 ft. 6 ins. The power unit is the Leyland 9.8-litre, 125 b.h.p oil engine fitted with Aphonic injectors.

An underfloor-engined, single-deck chassis of Guy manufacture makes its first appearance at the Show, and this model employs the new Gardner 6HLW horizontal oil engine, which was first announced in "The Commercial Motor " dated September 1. The chassis shown is one of a range and has a hydraulic coupling and four-speed epicyclic gearbox operated by compressed air. As the crankshaft is offset from the centre line of the chassis, the axle also has an offset overheard-worm drive, so maintaining a neutral angle in the propeller shaft in both planes when under full load.