SWEEPIM HANGES IN BEDFORDS
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New Oil Engine Offered in Latest Bedford Range : Forward-control 4and 5-tonners and New 6-tonner,s' Introduced : Leyland 0.350 Engine for Certain Export Models RUMOURS have been circulating for many months about a new Bedford range and a new oil engine. Vauxhall Motors, Ltd., Luton, made the long-awaited announcement in Britain yesterday.
The more important new features include a Vauxhall-made 97 b.h.p. oil engine and a 115 b.h.p. petrol engine which incorporate many common components, a new 6-ton chassis and new forward-control 4-ton and 5-ton models, All existing models except the 12-cwt. van have been modified.
Vauxhall are now able to offer a full range of 20 truck models, varying in capacity from 25 cwt. to 10 tons.
Undoubtedly, the most important innovation is the new 300-cu.-in. oil engine. This unit, which has been designed and developed at the Luton factory and is being built in the new Dunstable plant, marks the entry of yet another vehicle maker into oil-engine manufacture.
It has a bore of 3.875 in. and stroke of 4.25 in.. and is thus similar to the Bedford 300-Gil-in. petrol engine. The new unit is, however, in no way a 'conversion of the previous petrol engine, The reverse is the case, for the present petrol engine has been derived from the new compression-ignition unit.
This derivation has allowed the use of common components in both units, including the crankshaft, camshaft, rough cylinder block and crankcase casting, crankshaft bearings and oil pump. This design technique helps not only to cut the initial cost of the engines, but to reduce holdings of engine spares.
The new engine is a six-cyfindered it is possible to accommodate large valves within the bore-size limitations.
An in-line C.A.V. fuel-injection pump, with vacuum governor, is used and a simplified type of fuel-line connection has been incorporated to make it possible for a temporary line to be quickly improvised from an existing length of pipe in the event of fracture. A Clayton Dewandre vacuum exhauster is driven in tandem with the fuel pump.
Cast-aluminium pistons carry five rings. The top one is chromiumplated and lapped to half its width to give early bedding-down. Scuff bands are machined into the pistons above the rings to form a heat barrier, with the object of preventing the rings from sticking.
Slip-fit dry cylinder liners are used, and the cylinder head is secured by 14 high-tensile-steel -1'k-in.-diameter studs which pass through the depth of the cylinder block. These studs are bronzeplated as a protection against rust.
The seven-bearing crankshaft is forged from high-tensile steel, and the fillets are cold-rolled to improve the strength at the junction of crankpin and web by, it is claimed, as much as half. Journals and • crankpins are Tocco-hardened and the main and bigend bearings are steel-backed copperlead units flashed with lead indium.
A helical gear train driven from the forward end of the crankshaft provides the auxiliary drives, and provision is made to accommodate a hydraulic pump for power steering. Manganesemolybdenum steel gears are used. A full-flow filter is included in the lubri
eating circuit. and the high-pressure gear-type pump is driven directly from the camshaft.
The maximum gross torque output 01 the new engine is 217 lb.-ft., which is developed at 1,400 r.p.m. The torque characteristics are such that between 800 r.p.m. and 2,200 r.p.m. at least 200 lb.-ft. gross torque is developed.
On full load a specific fuel consumption of less than 0.4 lb./b.h.p./hr. over a substantial part of the speed range is claimed. The makers also say that, when hauling 5-6-ton payloads, the engine has returned more than 19 m.p.g.
In view of the number of oil-engined components incorp&ated in the 300cu-in, petrol engine, its robustness is outstanding and it should be capable of a long trouble-free life. It has the same bore and stroke as the compression-ignition unit, and the compression ratio is 6.85 to 1, as against 17.1 to 1 for the oil engine. A gross power output of 115 b.h.p. at 3,000 r.p.m. is quoted, and the gross torque rating is 240 lb.-ft. at 1,400 r.p.m.
Important modifications have been made also to the 214-cu.-in. petrol engine. This unit, which is used in the 25-cwt. and 35-cwt. models and the 2.7, 3-, 4-, 5-, and 6-ton chassis, has been largely designed with the object of providing a substantial increase in power output without detriment, to long life or economy. The cylinder head, valve gear, induction manifold, carbnretter, pistons and connecting rods have been redesigned.
Research has shown that whilst the compression ratio • of an engine is limited by the quality of fuel used, of 6.75 to 1 (as opposed to 6.22 to 1 of the former unit) to be used with commercial-grade petrol.
The valves are inclined at an angle of 12' 44' to the vertical centre line of the engine, and the redesigned combustion chamber has allowed the use of a larger intake-valve head and port than previously. This in turn gives greater breathing capacity, and the induction.manifold has been enlarged and smootheel out to allow a greater weight of charge to be taken in.
A completely new carburetter is employed. Its advantages include an arrangement of the fuel passages relative to the final discharge orifices to eliminate percolation. Thus, hot starting in high ambient temperatures can be achieved without difficulty. A modification to the float-chamber bowl has improved the spill angle, which means that the vehicle can operate effectively on steep slopes ivithout fuel spilling from the jets into the manifold.
Two basic types of carburetter are offered with this engine; one is ungoverned and is normally employed in the lighter range of vehicles, whilst the other has a gas-velocity governor built into it for use with engines in the heavier models.
The pistons have been entirely redesigned and are of aluminium alloy, replacing the former cast-iron pistons. A fully floating gudgeon pin is now incorporated. The lighter weight of the pistons contributes towards the reduction of their inertia and thus reduces the big-end-bearing, load. •A new design of Scraper ring exerts .6 a20 higher cylinder-wall pressure and thus promotes oil economy.
A gross power output of 100 b.h.p. at 3,600 r.p.m is developed by the new 214-cu.-in, engine, compared with 90 b.h.p. at 3,200 gun. for the earlier model. Similarly, the maximum torque output of 184 lb.-ft. at 1,200 r.p.m. represents an increase of 6 lb.-ft. torque.
A modified gearbox design gives improved synchromesh action and faster gear changing, whilst greater tooth-contact areas should promote increased life.
A new hypoid rear axle, which is fitted to all models of 4-ton capacity and above, ha i been developed. Its most important feature is a fourpinion differential_ It .is rated at 17,000 lb.-1,000 lb. • heavier than the previous unit. The half-shaft diameter has been 'increased by ,k in. to 1.* in., and the splined ends have been altered, there now being. 42 shallow splines instead of 16 deep splines.
.With the introduction of the new forward-control models, front-axle loadings have increased. A new 5,700-lb. front: axle has been deVeloped for 4-, and' .6-ton •modeli, but the 6-ton forward-control 152-in.-wheelbase chassis 'and the 132-in.-wheelbase oilengined model have 8,200-lb. front axles. A detail improvement which affects all forward-control models is the addition of a hub step ring to assist entry to the cab.
Telescopic dampers are fitted as standard—at least at the front—to all the new models, but in eases where they are not provided as standard equipment at the rear they are offered as optional extras. Certain models have Thompson self-adjusting bail joints in their steering linkages and the 25-35-cwt. and 2-ton chassis have been equipped with moulded brake facings to increase fade resistance.
The cabs on all models have been modified. The new mounting arrangement of the normal-control cab is particularly noteworthy. As before, the cab and front-end assembly is carried on a sub-frame, but this has been strengthened and a revised form of three-point mounting has been adopted.
This consists of one rubber mounting at the rear and single rubbers at each side of the sub-frame amidships.
These forward mountings are close to where the control pedals pass through the floor, and the arrangement reduces movement between the cab floor, pedals and gear lever when travelling over rough ground.
Forward-control cabs have strengthened floor and door-pillar structures, and the new form of three-point mounting is again employed. A redesigned radiator grille has been introduced on all the forward-control models, whilst the 4-, 5and 6-ton normal-control vehicles also have a new radiator grille to give a greater air flow to the larger radiators used.
Taking the complete Bedford range, model by model, the smallest vehicle is the CA 12-cwt. van, which remains unaltered in specification.. Next up the scale is the 25-cwt. chassis, which is offered with the new 214-cu.-in. petrol engine or with the Perkins P.4 oil engine. The normal-control cab supplied with the chassis is unchanged in appearance, but the redesigned mounting arrangement is incorporated.
A special pick-up chassis, similar to the 25-ewt. model, is offered for export. It has a gross weight of 5,000 lb. The 35-cwt, chassis is.basically similar to the 25-cwt. model, but has heavier . rear. springs.
• Two 2-tonners Two 2-ton chassis are offered, both being lightened versions of the former 3-ton model. As with the 25-cwt. and 35-cwt. models, petrol and oil engines are available. The long-wheelbase 2tonner, which has a wheelbase of 11 ft. 11 in., is for export only, whereas the short-wheelbase model (9 ft. 11 in.) is offered on all markets. An-11-ft. 11-in.wheelbase 3-tonner is also available.
The middleweight range of chassis consists of 4-, 5and 6-tonners, all of which are available with either normal or forward control. Three wheelhases of 4-tonner are available: normal control, 10 ft, and 13 ft. 11 in., arid forward control 11 ft. These wheelbases apply also to the 5-ton chassis, the principal difference between the two models being in the tyres.
Four basic 6-tanners are offered. Two are normal-control models with 10-ft. and 13-ft, 11-in. wheelbases, and two are forward-control chassis with II-ft, and. 13-ft. wheelhases.
The 4-tonners have 7.00-20-in. (10-ply) tyres the 5-tonners, 7.50-20-in. (10-ply), and the 6-tonners, 7.50-20-in. (12-ply).
Choice of Engines
The 4and 5-tonners are offered with the choice of either the 214-cO.-in. petrol engine or the 300-cu.-in. oil 'engine, although the 300-cu.-in. petrol Unit' is primarily for export. The 6-tonners haVe either the 214-cu.-in. or 300-cu,4n. petrol engines or the 300-cu.-in. oil engine, but the 214-cu.-in. petrol unit, is not available with the 13-ft. wheelbase forward-control 6-ton chassis, which is for the home market only.
Flitch plates are standard on all the 6-ton models and are offered as optional on the 4and 5-tonners. A normalcontrol 8-ton tractor, basically similar to the 4-tonner except for springs and tyre equipment, is available. This is offered with either the 214-cu-in, petrol engine or the 300-cu.-in oil engine.
The Big Bedford 7-ton forwardcontrol range is marketed with the Bedford 300-cu.-in. petrol engine or the Perkins R6 Mark 2 340-cu.-in. oil engine, but on export models the Leyland 0.350 oil engine is offered. This is an interesting departure.
Mechanically, the 7-ton chassis are little changed, other than in respect of the power units, modifications being confined to suspension, gearbox and rear axle.
As a tipper, the 7-tonner has a wheelbase of 9 ft. 8 in. and has 8.25-20-in, (12-ply) tyres, The other 7-tonner is a 13-ft. wheelbase model with 9.00-20-in. (10-ply) tyres, A 10-ton tractor unit is also available, it has a 7-ft. 2-in, wheelbase with 7..50-20-in. (8-ply) tyres.
The Big Bedford passenger chassis, which has a wheelbase of 18 ft, and is suitable for 41-seat luxury bodywork, has the Bedford 300-cu.-in. petrol engine as standard, with the option of the Perkins R.6 Mark 2 oil engine. Similarly, the Bedford R-type 4 x 4 chassis is now powered by the new 115 b.h.p. petrol engine.
It is impossible to give a complete list of the prices Of the new models, but it can be taken generally that the petrolengined normal-control lightweight models are between £25 and 131 more expensive than the previous production models and the oilers are between £31 and £38 dearer. The 4-ton and 5-ton petrol-engined vehicles cost about £35 more, but the oilers are at least £50. cheaper.
Various accessories for the new models are offered by Vauxhall Motors at extra cost. These include a range of fresh-air heaters, a 60W. fog lamp, windscreen washers, reversing lamp. an extra driving mirror, a petrol-tank lock and a sump guard.
A two-man passenger seat is. offered on all forward-control cabs' as an optional extra costing a mere 1.3.
A 6-ton forward-control I o rr y, powered by the new 214-cu.-in, petrol engine, was offered to The Commercial Motor for test this week. Its performance, writes John F. Moon, was extremely satisfactory and particularly emphasized the improvements made to
the power unit. The vehicle handled well and was in no way tiring to drive. Suspension was good over all classes of road surface, and the brakes were safe and positive. Fuel economy and engine power were outstanding.
The vehicle tested was an 11-ft.wheelbase chassis, with standard 14-ft. drop-sided body. It had a 7.4 to 1 ratio rear axle and 7.50-20-in. (12-ply) tyres, and had covered over 8,000 miles before the test.
. Unladen kerb weight was 2 tons 17 cwt. 3 qr.; payload, 6 tons 1 cwt. 3 qr., and driver and passenger, 3 cwt. 2 qr., giving a gross vehicle weight of 9 tons 3 cwt.
" C.M." Test Figures
Test results Were as follows:
Fuel Consumption; (a) Low speed. undulatingr ou t c, 10.8 m.p.g. at 25.7 m.p.h. average speed; (b) high speed, undulating route, 9.7 m.p.g. at 30.5 m.p.h. average speed.
Acceleration; Through gear, 0-20 m.p.h., 14.25 sec.; 0-30 m.p.h., 29.1 sec.; direct drive, 10-20 m.p.h., 24.7 sec.; 10-30 1-n.p,h., 50 see.
Braking: From 20 m.p.h., 23.25 ft. 118.6 ft. per sec. per see.); from 30 m.p.h. 50 ft. (19.4 ft. per sec. per sec). 'Braking area, 41 sq. in. per ton gross weight.
Gradient Test: On a 1 in 61 gradient the vehicle made a smooth restart in bottom gear, using half throttle.
Weight Ratio: 0.545 b.h,p. per cwt. gross weight as tested.
Turning Circles: 44 ft. both locks. Price: £981, including cab and body, plus £185 9s. 6d purchase tax.