Integral Constr in 30 m•p • h.
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81,1-tonner INTEGRAL, all-aluminium construction, an unladen weight of under 3 tons and a horizontal oil engine mounted amidships are some of the outstanding features of a new vehicle which will be seen at the Commercial Motor Show at Earls Court. This maximum-load four-wheeler has been designed and built by Mann Egerton and Co., Ltd., Norwich, in conjunction with the development department of the British -Aluminium Co., Ltd., using Dennis engine, transmission and other running components.
By using lightweight frame-and-body construction and reducing the use of ferrous metals to a minimum, the vehicle weight in taxation condition is less than 3 tons. The designers have allowed for a payload of 8i tons to be carried legally at 30 m.p.h. under existing regulations. Welding has been used wherever possible, the only bolted or riveted joints being at points of wear where replacement may be necessary.
All-welded Framing The framing of this revolutionary lorry has been fabricated from NS5 hard hall-alittilinium alloy and is Argonaut welded, except where short runs and thin material sections have made this system impracticable, in which case Argonarc welding has been used. The main runners are 13 in. deep and of J-section, with the top flange welded in place after the cross-members have been put in place. At the forward end, below the cab, the section is reduced to 8 in., and at the rear the lower flange is tapered up sharply where the floor loading is lowest. The frame members are parallel and have a width of 2 ft. 111 in.
Eleven full-width cross-members pass through the main members, which are slotted. The cross-members also are fabricated from flat plate, with capping strips welded to their top edges and strips welded to their lower edges to form an inverted T-section between the longitudinals. The plates are bent to form an angle section outside the main runners, and some of the cross-members are gusseted to give additional strength at stress points. The front engine support is a U-section pressing, and all the chassis frame members are welded in position.
The brackets for the front semi-elliptic springs are fabricated from aluminium with steel forks for the shackle-pin wearing sections. The aluminium plates are welded to each side of the frame longitudinals and extend below the frame. The forks fit within these plates and are attached by fitted bolts. Malleable iron brackets are bolted to the side members for the real springs and Silentbloc bushes are used at all sprint anchorage points.
A conventional H-section nickel-steel beam is usec for the front axle. It is similar to that fitted to the Dennis Centaur. The rear axle is a new Eaton twospeed unit With an offset differential housing. The standard ratios are 6.14 and 8.52 to 1 and the change is effected by electric solenoid.
The Dennis engine is the new horizontal 5.5-litre uni1 as fitted to the Pelican lightweight coach chassif, described in last week's issue of The Commercial Motor, This engine develops 92 b.h.p. at 2,200 r.p.m. and ha.,, a maximum torque output of 241 lb.-ft. at 1,250 r.p.m. The exhauster for the brake servo is driven from the front of the camshaft, and the water pump and dynamo are drivenin tandemfrom the timing-gear train at the rear of the engine. Mounted alongside the gearbox. where it is readily accessible, is the centrifugally governed C.A.V. injection pump. The single-dry-plate clutch. has a diameter of 131 in. A standard Dennis heavy-duty fly speed constant-mesh gearbox affords ratios of 6.48, .28, 2.715, 1.63 and 1 to 1, with a reverse ratio of 8./ to I. The gear lever is linked to a relay lever moun ed across the frame ahead of the engine and to the s lector mechanism by a rod running above the engine.
Two steel brackets and one aluminium, which are bolted to the frame members, support the engine and gearbox unit. A single Metalast k bush is used at the front of the cylinder block, and t o swinging links from the rear suspension, the attachniejit points being on the clutch housing.
A lightweight radiator is mou4ted on rubber in the frame ahead of the front axle, ith its top level with the upper flanges of the frame side members. It is pressurized to 5 above atmospheric and carries a fan which is driven from the engine crankshaft through a shaft with flexible couplings.
Marks cam-and-double-roller steering gear is used.
The Girling hydraulic braking system incorporates a Clayton Dewandre vacuum servo mounted in the frame at an angle in order to afford a straight linkage from the pedal. A large aluminium reservoir is carried across. the frame behind the cab. The front brake drums are 16 in_ ,in diameter, with 3-in-wid facings, and the rear
drums have a diameter of 15i in , With a facing width of 5 ie. The hand brake is linke rear wheels only. . mechanically to the A 25-gallon aluminium fuel ta is strapped to the near-side frame member. This s also welded, as is the brake reservoir, and such detail has been contributory to the low unladen weight of the complete vehicle. The body floor plates have a t ead-plate pattern and are riveted to the frame, but the extruded-section rave rails are bolted in position for ea e of replacement. A headboard, fitted as standard, is constructed of highstrength alloy to give additional cab protection.
Embossed, unpainted aluminium panels are prefabricated by welding and riveted to the extruded-section cab frame. These embossed panels have been found to hide scratches which occur in service, besides having a slight stiffening and anti-drum effect.
The cab, which is full width and of a modern styling with no radiator grille, is mounted on four Metacone units. The aluminium floor is combined with the cab assembly, thereby ensuring full insulation from frame vibration. A special brightfinished aluminium has been used for the exterior moulding strips.
A stout crash-plate, constructed of 16 s.w.g. alloy, is fitted inside the front panelling of the cab as an additional safeguard. The front and rear wings are also of 16 s.w.g. aluminium and the front bumper is an extrusion of material similar to that which is used for the cab mouldings.
Strain-gauge Testing
The prototype vehicle which will be seen at the Commercial Motor Show will be subjected to extensive strain-gauge testing at the Motor Industry Research Association's proving grotted at Lindley. The underframe has already undergone extreme unloading at vital points and has shown no signs of fracture or distortion.
The low unladen weight, in addition to permitting a heavy payload to be carried, will also make for marked economy when running unladen, a condition still further improved by the two-speed axle and small engine. Another important factor is that the underfloor mounting of the engine increases accessibility for routine maintenance, reduces the time needed for engine changes and makes a short transmission line possible. It is good as an aid to driver comfort, leaving the cab clear of an engine cowl and removing the distraction of noise and fumes; it also makes the cab suitable for a fun-width seat.