Volvo Enters the Heavy Market
Page 59
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ADVANCE details of a new range of normal-control fourand six-Ilk-wheeled chassishave, been six -,wheeled to The Commercial Motor" by A.B. Volvo, Gothenburg. Sweden, before the general announcement in Europe. Production is planned to start this year and representative chassis will . be displayed at the Brussels Show next January. r • The . new models have payload capacities ranging from 8 tons-la 12 roils, and features include a 150 b.h.p. six-cylindered direct-injection oil engine, .five-speed overdrive-top synchromesh gearbox and a two-speed hypoid-driven axle as an optional 'extra. • . The 9.6-litre engine, with a toroidal ,chamber machined in the crownof the 'Pistons, develops its maximum power at r.p.m., and 428 lb.-ft. torque is available at 1,100 r.p.ni.. it has a castiron cylinder block With detachable wet liners, the upper seal b.eing made by the head gasket, whilst two washers form a
seal at the base of the block. •
Engine Design .
Through-bolts are used to. secure the block to an aluminium-alloy crankcase, -which is strengthened by extending the casting well below the crankshaft centre
• line and reinforced by drOss-membeni drawn through the forged-bearing caps.
The pistons are of forged aluminiumalloy and have three compression and two scraper rings, the top ring ;being chrornium-plated.
A Toccosha rdened seven:Ilea ri ng • crankshaft is employed and both main and connecting-rod bearings are of prefinished steel-shell pattern with lead• bronze lining. Fins arecast in, the aluminium-alloy base foradditional' cooling. There are two interchangeable cylinder heads, •eich covering three bores and having in4vidual oil-bath air cleaners. Replaceable-type seats, are provided for the exhaust valves.. Apartfrom the fan and water pump, all other auxiliaries are gear-driven from the front of the crankshaft.
The • engine-oil filtration system includes a floating-screen unit in the base, and all oil is pumped through a rotatable self7cleaning element, actuated by the clutch pedal, before reaching the main supply. Fuel is supplied from a 26-gallon tank to the engine by a feed pump actuated by the injection pump. which has a pneumatically. operated governor. The engine,.clutch and gearbox are of unit construction; supported in the chassis on four-point rubber mountings; the two rear mountings being V-shaped members attached to the flywheel housing.
The Borg. and Beck -16-in.-diameter single-plate dry clutch has a frictionface area of'276 sq. ins. The five-speed gearbox, with ratios ranging from 6.07 to 0,78 to I forward, has synchromesh arrangements for the second to fifth ratios.
Transmission to • the rear axle is through mechanically jointed shafts. and in the six-wheeler the final axle is a trailing unit. The driving axle in all models incorporates hypoid-bevel gearing, a standard ratio of 6.5 to 1 being supplied throughout the range. An alternative electrically operated twospeed axle is available, the ratios being 6.14 and 8.36 to 1.
As in other Volvo chassis. a transmission parking brake is fitted, the arrangement comprising two internal-. expanding shoes, so thSt the hand brake can be used without danger of grabbing while the vehicle is moving. A bonded cast-iron lining is fitted to the transmission drum.
Lockheed Brakes
The main system is operated through a Lockheed Hydrovac unit with twin hydraulic cylinders at each wheel. The Volvo is also available with the Air-pair brake -gear for operation with trailers having air-pressure braking systems. Drums of 16-in, diameter are fitted to all axles, the four-wheder.having a total friction-facing area of 518 sq. ins.
The two-axled version is available in wheelbases of 12 ft. 6 ills., 14 ft. 5 ins. and 15 ft. 5 ins. The two six-wheeled chassis employ similar. wheel positions to the medium and long-wheelbase fourwheelers, but with a trailing axle arranged 4 'ft. 1 in. behind the driving axle. Equipped with 11.00 by 20-in. tyres, the overall width of all models ir 7 ft. 8 ins.
In chassis and cab form, cOmplete with -spare wheel, fuel and accessories, the long-wheelbase model weighs 41 tons and is scheduled.for a gross laden weight of 131 tons. From the 'back of the cab to • the end, of the frame it measures 16 FL 2 ins. The larger sixwheeler weighs 5 tons 8 cwt. unladen and is scheduled for a gross load of 171 ions. Its frame length behind the cab is 19 ft. 7 ins.