New Dumper and Tractor Added to Atkinson Range
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More Powerful Engines and Improved Braking Mark Design Trends in Heavy-vehicle Makers' Range: Wider Radiators Enhance Appearance
GENERAL design trends indicated by the range of models to be shown at Earls Court by Atkinson Vehicles, Ltd., Walton-le-Dale, Preston, include the use of more powerful engines and improved braking systems, and in a number of cases the type of gearbox employed is of special interest. A sixwheeled dumper represents an entirely new model, and a four-wheeled 11-ton tractor is another notable addition to the company's standard products. • Representing a new project for the concern, a de luxe cab will be exhibited having plastics panelling.
Known as the DT1366CA, the six wheeled dumper is similar to a 12-cu.-yd. model developed for South African Railways, of which 47 have been exported. This vehicle will be shown equipped with a Cummins HU-6B oil engine developing 158 b.h.p. at 1,800 r.p.m. and a torque of 490 lb.-ft. at 1,250 r.p.m., but will be available with a Gardner 6LX 150-b.h.p. engine or a Rolls-Royce C.6NFL unit. The Rolls-Royce produces 200 b.h.p. at 2,100 r.p.m.
Outstanding features of the Cummins engine• include four-valve cylinder heads and a pressure-time fuel-injection system. It is a naturally aspirated six-cylindered unit with a bore of 124 mm. and a stroke of 152 mm.
Power is transmitted through an I8-in. single-dry-plate clutch to a. ZF six-speed gearbox which provides. a direct top gear and a bottom gear ratio of 8.98 to 1. The high torque rating of the gearbox is ample for the increased output of the Rolls-Royce engine, and the range of ratios enables a "crawling speed" bottom gear to be employed without sacrificing performance at higher road speeds or necessitating the use of an auxiliary box. In standard form the gearbox is of the constant-mesh type; an allsynchromesh unit is also available.
From the gearbox, the drive is transmitted through a propeller shaft with Hardy-Spicer universal joints to both rear axles, which are of the worm type with c40 8+-in, centres giving a final-reduction ratio of 8.25 to 1. Alternative ratios are available.
The single rear wheels carry Michelin X 14.00 by 20 20-ply tyres, whilst similar 11.00 by 22 14-ply covers are fitted to the front wheels. An air-pressure dualbraking system is employed which is supplied by an engine-mounted compressor, the brakes of the front wheels and the twin rear wheels being operated by separate air circuits. A generous brakefacing area is provided by 16+-in. by 4-in. drums at the front and rear drums of 161 in. by 6 in.
A particularly robust chassis frame is based on 14-in. by 6-in. joist-section main members, which give a flat mounting surface to the rear of the engine bulkhead. Approximately 21 ft. 1 in. in length, the chassis has an overall width of 7 ft. 51. in. A heavy-duty front bumper is equipped with a towing bar, and there is a towing jaw at the rear.
Power Steering
Other chassis components include a Manes continuous-flow power-steering system of the integral type and a 54-gal. fuel tank. A 24-volt double-pole electrical system is used in conjunction with high-capacity batteries carried in side crates.
A one-man half-cab is a standard feature of the dumper and the Show vehicle will be equipped with a conventional all-steel dumper body operated by twin hydraulic rams. The chassis is available with twin rear wheels and is readily adaptable to the mounting of cranes or other mobile equipment requiring a heavy-duty carrier with ample power. Based on a conventional drop-frame type of chassis, the ST1045 11-ton tractor is essentially a new model designed for a Scammell automatic coupling. This will be a Mark 2 vacuum-operated unit.
A relatively high power output for this type of vehicle is provided by a Gardner 5LW unit, which develops 94 h.h.p. at 1,700 r.p.m. and a torque of 300 lb.-ft. at 1,300 r.p.m. Performance of the vehicle is further enhanced by the use of a David Brown 557 five-speed gearbox giving an overdrive ratio of 0.77 to 1 and a bottom gear ratio of 6.06 to 1. Power is transmitted to the gearbox through a 16-in. single dry-plate clutch, the slipping torque of which is 510 lb.-ft. A 14-in. Kirkstall hypoid rear axle has a ratio of 5.83 to 1.
Tyre equipment comprises 7.50 by 20 10-ply covers, which are fitted to all the wheels. Vacuum servo-assisted hydraulic brakes are employed to actuate brake shoes with a width of 3 in. in the front drums and of 6 in. in the rear drums, respective drum diameters being 16 in. and 15in. Steering gear is the Marks cam-and-double-roller type, and other details include a 24-volt double-pole electrical system and a 45-gal. fuel tank. Approximate chassis dimensions include a, length of 14 ft. 6 in. and a width of 7 ft. 21 in. It is claimed that the L1786XA eight-wheeled chassis, to be shown fitted with maximum-capacity tipper body, is the first load-carrying standard vehicle of its type to be equipped with a fluid flywheel and semiautomatic gearbox. This should be a boon to many tipper operators eugaged on rough site work, to whom the performance and reliability of the transmission components is of major importance, The chassis is powered by a Gardner 6LX oil engine, and torque is transmitted from the fluid flywheel to a Self Changing Gears RV.38 air-pressure-operated epicyclic five-speed gearbox and to twin driving axles of the worm type. The final-drive units have 84-in. centres and provide a reduction of 61 to 1. An engine-mounted compressor is used for operation of 164-in. by 4-in, front brakes and 16I-in. by 6-in, rear brakes. Both front and rear wheels are equipped with Michelin X 900 by 20 covers.
A buzzer is incorporated in the system which gives warning of reduced air pressure. Air operation is also employed in the windscreen wipers.
This vehicle is equipped with the concern's de luxe cab, which is produced in the workshops and comprises glass-fibre panels mounted on a composite hardwood and metal framework, the timber being pre-treated with Cuprinol. The cab is built in five main sections; these include two near-side and two off-side units and a roof section, the Wings being formed in two parts integral with the vertical sections. Steel reinforcing members include two wheel-arch brackets and two corner truss plates.
Integral Headboard
Two layers of chop strand mat are employed for the panelling, reinforced with two extra layers at highly stressed points. The roof is reinforced with longitudinal ribs of plastics moulded to the Panel: A headboard is formed in the roof section and if required can be glazed to protect the nameplate of the operator and illuminated by a separate lighting circuit. The windscreen is of the-full wrap-round type and provides a total glazed area of 174 sq. ft., whilst another feature aiding visibility is the use of twin screen wipers, the near-side wiper being mounted on the lower side of the glazing. This gives the driver an improved view of the kerb in rainy weather.
Standard cab equipment includes a Iheater fitted with a four-duct demister system and seats upholstered in Tygan having Dunlopillo cushions.
An increased output is also provided by the Gardner 6LX engine in the case of the L1786TA eight-wheeled chassis having a trailing axle, which will be shown fitted with a 3,500-gal, twin-compartment stainless-steel tank. This vehicle is equipped with an air-pressure braking system, and the cab is of the de luxe type.
The cab will be shown sectioned in the case of an L1786 standard eight-wheeler, together with a sectioned platform body. Power is provided by a Gardner 6LX engine, and new features include a Hydrovac power-operated braking system, which is also fitted to the L1786T eightwheeled trailing-axle chassis. The latter is powered by a Gardner 6LW engine. Both models are equipped with the de luxe cab.
Fully described in the March 7 issue of
The Conunercial Motor, the DT745 fourwheeled dumper is powered by a Gardner 5LW engine and will be shown carrying a 5-6-cu.-yd. scow-ended body. Features of the vehicle include Marles power steering, a Hydrovac braking system and a spiral bevel double-helical rear axle.
Largest vehicle on the Atkinson stand will be the Omega 6 x 6 tractor (The Commercial Motor, November 15, 1957), designed for desert operations in Saudi Arabia. Reports from that country show that the Rolls-Royce C.6NFL 250-b.h.p. oil engine, in conjunction with a Self Changing Gears eight-speed epicyclic gearbox, is providing a fuel consumption of 4.3 m.p.g. under unfavourable desert conditions. This represents a saving of 40 per cent, compared with the consumption of other vehicles of the same capacity, and affords a substantial increase in the payload that can be carried when long ruts are entailed. .
• Although designed as a tractor, the Omega chassis is _admirably suited for carrying dumper bodies up to 24-01.-yd. capacity and could be producedas a 6 x 6 or 6 x 4 vehicle. It is available with a Cummins N.R.T.O. turbocharged
Oil engine developing 335 b.h.p. at 2,100 r.p.m. and a torque of 900 lb.-ft. at 1.500 r.p.m.
All the standard vehicles shown incorporate front brake drums giving a larger facing area than that provided by their predecessors. Radiators of increased width are employed throughout the range, which is a favourable feature with regard to appearance and has enabled cooling capacity to be increased for a given number of tubes; cores containing 30, 60, or 90 tubes may be specified. Multiwheelers in the range are normally equipped with the standard type of fourspring bogie but are available with the Kirkstall fully articulated bogie for offthe-road work.
A notable detail of those chassis fitted with Gardner 6LX engines in unit with the gearbox is the use of Metacone double-pad mounting feet. These are bolted to both the engine and gearbox.
A T746 7-ton four-wheeled tractor will be shown in the demonstration park at Earls Court. This is powered by a Gardner 6LX oil engine and is equipped with a double-reduction spiral-bevel rear axle.