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( and Safety
in Brith
7ehicles
ASthe only commercial vehicle show in Great Britain this year, the Scottish Motor Exhibition, which opened last Fri-day and closes tomorrow, gives manufacturers who have introduced new models since the 1954 Earls Court show a chance to secure a wide public. It also provides those people in the commercial-vehicle world who have technical inclinations with an opportunity to review the progress (or otherwise) that has taken place in the preceding six months. Surprises are not expected, but are, nevertheless, gratefully received.
This year the surprises were principally limited to an Albion 30-35-cwt. underfloor-engined chassis, a tractor version of the Morris 5-ton oiler and a new Beadle 41-seat coach fitted with an A.E.C. five-speed gearbox.
There are several other completely new models, however, including the Dennis Heron 3-tonner, the Commer Superpoise 15-cwt. and 11-ton range, the Guy Warrior 8-tonner and the Thornycroft Swiftsure 6-64-tonner.
Many chassis have been modified with the object of giving improved and safer performance. The new Construction and Use Regulations affecting weights and widths have also produced a few changes, although none of these may be termed startling. The general theme of the Show, therefore, must be taken as greater economy of operation, exemplified by the increased number of oil-engined exhibits and, in certain instances, the reduction of unladen weight. , Greater safety can be seen in the improved conditions for the driver, typified by more powerful brakes which are lighter to operate, power-assisted steering in the same vein and better all-round visibility.
Apart from the surprise 'caused by its appearance at the Show, the Albion Cairn is interesting in being the lowest capacity underfloor-engined goods vehicle produced in the kingdom. Its derivation from the heavier Claymore chassis is obvious, but it differs in respect of a lighter frame and suspension, smaller tyres and the use of a spiral-bevel rear axle—the only current Albion model to use one. as a unit at three points. The mounting position is below the frame and between the two axles, and mechanical linkages •are used from the controls to the unit.
A one-piece propeller shaft takes the drive to the rear axle, which is fully floating, with a pressed-steel banjotype body. Tapered-roller bearings are used for the hubs and for the crown-wheel and differential mountings, and the pinion shaft is carried by double tapered-roller bearings at the front and a double-row roller bearing at the rear. Braking is by the Girling hydraulic system, with twoleading-shoe units at all wheels. An the brake drums are 14 in. in diameter and the front-brake facings are 2-1 in. wide, those at the rear being 3i in. wide. The total frictional area of 324 sq. in. gives a good areaweight ratio when the vehicle is operated at the recommended gross weight of 41 tons.
The Cairn is offered with a 10-ft wheelbase and 6.50-20 (6-ply) tyres. A standard three-seat cab can be supplied with the chassis, and the vehicle is suitable for bodies up to 13 ft. 9 in. long.
A commendable feature of this design is the low cab floor. This is of particular advantage when the vehicle is engaged on delivery service, as is also the good manceuvrability resulting from the short wheelbase and small turning circle of 40 ft.
Although the Albion Cairn is the only 30-cwt. chassis with a horizontal oil engine, there are several other chassis of similar capacity which use a conventional oil engine. These includefloe Austin and Morris LDo.2 30-cwt. models, powered by the B.M.C. 2.2-litre 55 b.h.p unit and the Seddon Twenty-Five, which has a Perkins P.3 2.36-litre 39 b.h.p. engine.
The oil engine is taking a firm hold on this class of delivery vehicle, and its sphere has spread even to the smaller ranges, such as the Trojan 1-ton chassis and the B17 Standard 12-cwt. model. Other than the Albion unit, all these engines have indirect injection, but it is not unlikely that direct-injection, engines of under 3-litre capacity will be forthcoming. It is known that experiments along these lines are at present being conducted. The advantages to be gained in respect of quietness and economy are noteworthy.
Higher up the scale of payload capacities, a new-comer is the Dennis Heron. This is perfectly conventional in design and employs a Perkins P.4 54 b.h.p. oil engine. With the aim of easing the lot of the driver, the fourspeed gearbox has synchromesh engagement. This gearbox ' is Manufactured and used extensively by another concern, so the spare-part problem should be reduced.
The engine mountings of the Heron have received careful consideration with a view to reducing vibration, although the single front mounting, which is a sandwich .unit, is carried on a flimsy-looking cross-member. Hydraulic clutch actuation is becoming a familiar featUre of British commercial-vehicle design and is used in the Heron. .Telescopic dampers—often offered as optional extras—are fitted to the front axle to give a more comfortable ride whether thevehicle be laden or unladen.
Good Driving Position When seen as a chassis and cab only, the Heron looks a little ill-proportioned by reason of the large cab. This
effect disappears, however, when a body is fitted-, and the cab shape can then be appreciated as one which gives excellent all-round visibility and easy access to the driving seat. The driving position is relatively high, but because there is an enclosed step ahead of the front wheels it is not difficult to get into the seat. Awkward blind-spots caused by the cab rear .corners have been almost eliminated by the deep and wide corner lights.
There. have been three new arrivals in the 3-ton and
5-ton class during the past 12 months. These are the Austin, Commer and toiorris ranges, all of which have conventional chassis. layouts but more comfortable cabs.
When the Cornmer models were announced, a new overdrive unit was also introduced, this now being avail able in the 5-ton. and 7-ton forward-control chassis..
The use of overdrives is spreading rapidly throughout i318 the car world, but not so quickly among the commercials, and usually only as a fifth ratio to the box, rather than as an auxiliary gear which can be used in conjunction with any of the main gearbox ratios. The alternative to this system is to employ a two-speed axle, such as the Eaton, which, provided that the correct ratios are specified, can function as an overdrive to provide economical running costs.
A new oil engine with a high governed speed is incorporated in the new Thornycroft Swiftsure
goods chassis, This engine, known as the .1.12.6, is a six-cylindered 4.18-litre unit, rated at 80 bh.p. at 2,600 r.p.m,, with a maximum torque output of 184 lb.-ft. at 1,600 r.p.m. it is reasonable to suppOse that. 'this engine will give the chassis a performance more akin to that of a petrol-engined vehicle, although retaining the customary oil-engine economy.
The general specification of the Swiftsure includes a five-speed, direct-drive-top gearbox, spiral-bevel rear axle and hydraulic brakes with a vacuum servo. The frame is a pressed-steel bolted assembly with a flat top line, thus simplifying the task of the bodybuilder.
Two wheelbases are offered-11 ft. and 13 ft. 6 in.— and the chassis arid cab weight is approximately 21 tons, bringing the licensing weight of the complete vehicle well into the "under 3 tons " class. In standard form the Swiftsure is supplied with an all-steel cab, but an all-plastics cab has been designed, and the Show model has this assembly.
The Guy Warrior, formerly the Big Otter, provides a good example of current British design in the 8-ton payload class. It is powered by a Meadows 4DC 330 85 b.h.p. oil engine, which is used in conjunction with. a Meadows five-speed gearbox and, as s.hown, it is equipped with an Eaton 16,500 two-speed axle. A single-speed hypoid-drive axle is 10 be offered as an alternative, but undoubtedly better performance will result from the use of the Eaton unit. •
Air-hydraulic braking is found in the Warrior. This system, which has all the power, hut none of the complications or time-lag of full air operation, has been shown to give excellent braking performance. The air
hydraulic actuator and master cylinder are rigidly mounted on a frame cross-member, as opposed to the more common arrangement of carrying the power cylinder, servo or master cylinder outside the frame. Other features of the Warrior point to its robust construction. Among these are the 9-in.-deep frame members and the all-bolted construction of' the frame, the heavy-duty cam and double roller steering gear and the use of helper springs at the rear. ,
-A fresh face among the many B.M.C. exhibits is the Morris oil-enginecl prime mover, suitable for use as an articulated unit at 12 tons gross weight. The tractor is an adaptation of the 5-ton chassis and has a 13.M.C, 5.1-litre oil engine rated at 90 b.h.p., and a full-forwardcontrol cab, the wheelbase being 7 ft. 1 in.
This exhibit has a single-speed axle, but when the tractor is fitted with a two-speed axle its permissible gross weight is increased to 15 tons. It is shown with Scammell automatic coupling gear, but will later be available with other proprietary makes of coupling or turntable. The provisional price fixed for the 12-ton tractor is £985, to which must be added £199 Is. 2d. purchase tax.
While on the subject of articulated vehicles, the new Brockhouse coupling gear should be mentioned. This was introduced last month and one of the features claimed for it is that it is interchangeable with the standard Scammell gear Of similar capacity.
A new-comer to, the field of heavy goods. chassis this year is the Thornycroft Trusty eight-wheeler. This is shown as a 24-ton-gross vehicle with double-axle drive, but is to. be made available alternatively with a single.
drive arrangement. • •
The new OR.6 six-cylindered oil engine used in this chassis develops' 140 b.h.p. at 2,000 r.p.m., with a torque rating of 420 lb.-ft.. at 1,000 r.p.m. The four-speed main gearbox is used With a two-speed 'auxiliary box, these being mounted in unit with the engine. The auxiliary box on the chassis shown has a power-take-off drive above the main propeller shaft, and it is assumed that this is to drive a pump when the vehicle is used as a tanker.
Four-spring suspension is employed for the rear bogie, the inner ends at each side being connected by rocking beams. This system is much lighter than the two-spring articulated type and is perfectly satisfactory for vehicles which are not expected to do much off-the-road running. For this reason, also, a third differential is fitted to the leading driving axle. Continuous-flow hydraulic powerassisted steering is available as an optional extra. The power rams act directly on the drag-link relay lever.
Heaviest of the goods vehicles is a Leyland-Dyson 20-25-ton articulated outfit, to be seen among the demonstration vehicles outside the hall. The tractor is
the.Beaver 14.B10 model, which has an 8-ft. 6-in. wheelbase, and is representative of the redesigned Leyland range introdited to take advantage of the new Construction and Use Regulations. It has a 125 b.h.p. oil engine, five-speed gearbox and 9-iti. worm-driven rear axle. Air'' brakes are fitted as standard and 10,00-20-in. (14-pIy) tyres are employed.
Leyland also show the redesigned Titan PD2/25 passenger chassis. As exhibited it is equipped with a 60-scat double-deck body, .made by Walter Alexander and Co. (Coachbuilders), Ltd., and the complete vehicle has an unladen weight of 7 tons 14.i ewt. It is one of an order of 125 for Glasgow Corporation Transport.
In addition to having the specially reinforced front springs specified by Glasgow Corporation, this chassis has a four-speed Pneumo-Cyclic semi-automatic gearbox. The Bendix-Westinghouse diaphragm-type airbraking system includes a 10-cu.-ft. twin-cylindered compressor, dual air reservoirs and a two-stage DI brake valve.
The rear axle of the Titan is an 8-in. underslurig-worm unit and, because Of the location of the' gearbox, the rear propeller-shaft centre bearing has been 'dispensed with. The cylindrical fuel tank is common to other Leyland goods and passenger vehicles—a' small .point but one which, helps to reduce manufacturing costs.
At the Show it was disclosed by Leylands that a fivespeed Pneurno-Cyclic gearbox had been developed and would shortly be going into production. This box is already specified fqr the new RT3/2 Royal Tiger Worldmaster coach chassis, which has a I6-ft. 3-in. wheelbase and an overall length of 25 ft. 11 in., the rear overhang being only 3 ft. 41 in.
The other double-decker at the Show' is a 66.-seater based on a Daimler C.V.G.6 chassis. This has a Willowbrooks full-height body, and the overall height of the bus has been kept down to 14 ft. This has been achieved principally, by lowering the gearbox so that it does not protrude above the frame side members, and mounting the body directly on the chassis so as to farm a semi-integral tyPe of construction.
Seen with this bus is the latestFreeline underfloorengined single-deck chassis, which has air brakes andair-assisted steering. This equipment is now offered as an alternative to the power-hydraulic brakes and hydraulically assisted steering.
A new Beadle 41-seat integral-construction coach makes its first appearance at this Show. It is the T.S.3 Mark 0.E.11 model, and it differs principally in 'respect of transmission. The .0.E.5 version, which is still in production, uses a Commer four speed synchromesh gearbox and 13-in.=diameter cIutch, whereas the later marque has an A.E.C.five-speed box' and a 151-in.diameter hydraulically operateffelutch the size of this box has necessitated an additional mounting for the engine-gearbox unit
Both models are powered by the Commer T.S.3 twostroke 105 b.h.p. oil engine, which has been modified slightly to meet the demands of the Beadle designers. A solenoid slop control is now used instead of a Bowden cable and a 7-in.-diameter dynamo is fitted.
Because there is insufficient room on the engine for such a large dynamo, it has been mounted behind the engine and is driven through a two-piece propeller shaft and 2-to-1 step-up gearbox. The drive for this shaft is taken from the old dynamo position and a triple V-belt is used,