Atkinson to Show Seven Eight-wheelers
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OF the nine vehicles to be displayed by Atkinson Vehicles, Ltd., on their stand at the Commercial Motor Show, at Earls Court, London, five will be eight-wheeled models. Two further eight-wheelers are to be Seen in the demonstration park. One will have a new type of hydraulic engagement for its lockable third differential.
Other models on the stand will comprise two 24-ton-gross tractive units, a recently introduced lightweight 14-tongross four-wheeler, and a 40-ton-gross six-wheeled tractor With Cummins 2l2-b.h.p. oil engine.
All the eight-wheelers have wheclbascs of 17 ft. 81 in,, and in every case but one the power unit is the Gardner 6LX. The exception is a 4,000-gal. insulated tanker, with A.P.V. bodywork, built for Monk ton Motors, Ltd., Uxbridge. This is powered by a Gardner 6LW 112-b.h.p. unit, and has a trailing-axle rear bogie, with Kirkstail spiral-bevel and helical-spur double-reduction driving axle. The gearbox is a David Brown five-speed directtop unit. Vacuum-hydraulic braking, using a tandem Hydrovac servo, is fitted, and the wheels have 9.00-24-in. (12-ply) tyres.
light-alloy Tipping Body Apart from the use of a -6LX engine, a similar specification applies to the exhibit to be seen in the colours of R. Hanson and Son, Ltd., Wakefield. This eightwheeler has a Comberhill 23-ft. 30-cu.yd. light-alloy tipping body and doubledrive rear bogie with overhead-worm axles. Milshaw tipping gear, with a racktype stabilizer, is employed.
A Homalloy 24-ft. light-alloy platform body will be mounted on an eightwheeler for Cawthorne and Sinclair, a model with a lightweight specification. It has a 107i-in. by *-in. chassis frame and lightweight springs on all axles, A saving in chassis weight of approximately 3 cwt. is obtained,
A Z.F. six-speed overdrive-top constantmesh gearbox is employed in this model, and it drives into a single-drive rear bogie with double-reduction axle. Two fuel tanks are fitted, one of 68-gal. capacity and the other of 30 gal.
A Yewco 4,000-gal. spirit tank is to be mounted on an eight-Wheeler built for Petrofina (Great Britain), Ltd. This chassis also has lightweight springs. The double-reduction axle of the single-drive rear bogie has a reduction ratio of 5.2 to 1, and the gearbox is a Pavid Brown five-speed direct-top unit.
The fifth eight-wheeler to be seen on the stand has been built for Bass, Rateliff and Gretton, Ltd. The new David Brown 657 six-speed overdrive-top gearbox and the new Kirkstall four-spring bogie are incorporated in this chassis. The unit has a top ratio of 0.717 to 1, with a 6.61-to-1 bottom gear, and drives into both triple-reduction axles of the rear bogie. The Marks steering gear has a hydraulic servo.
Air-pressure braking is fitted, and the wheels carry Dunlop 9.00-20-in. R.K.9 braced-tread tyres. The cab has a de-luxe specification, including tartan upholstery, and a radio. Lightweight rear springs and a 13-ton towing. jaw are other details. This exhibit will be displayed without a body.
Largest and most powerful of the Atkinson exhibits will be the BT 1366 CA six-wheeled tractor, which is similar in specification to 18 such vehicles recently supplied to Smith Africa, This 14-ft.wheelbase normal-control chassis has a Cummins NH 220 B six-cyfindered oil engine with a gross power rating of 212 b.h.p. at 2,100 r.p.m., and the recommended gross train weight rating is 40 tons.
The engine produces 585 lb:-ft. torque, and this is passed through an 18-in.-diameter single-plate clutch with hydraulic actuation into a Z.F. AK6-75 six-speed overdrive-top constant-mesh gearbox. The twin worm axles of the rear bogie have reduction ratios of 8.25 to .1, and arc driven through a third differential With air-operated locking mechanism. A split-circuit air-pressure braking system is fitted.
Z.F. steering with integral hydraulic power assistance is used. This unit has no external power rams or valves. A Crane semi-automatic fifth-wheel coupling is fitted, and there are twin fuel tanks with a total capacity of 99 gal. The tractor is 23 ft. 3 in. long and 7 ft. 11* in. wide.
Two Tractors
The two tractive units on the stand will both be T 746 X models with 6LX power units. Both have whcelbases of 8 ft. 9 in. and Z.F. six-speed overdrive-top gearboxes, but whereas the example built for Alfred Dexter, Ltd., has vacuumhydraulic braking, that for Sutton and Sons, Ltd., has air-pressure brakes. Double-reduction rear axles are fitted to both vehicles, and both examples will be seen with fifth-wheel 'semi-trailer couplings.
The ninth exhibit will be a fourwheeler introduced in November last year. It is a lightweight 14-ton-gross model derived from the L 644 11-tongross models, and is type-numbered the L 645 series. A Gardner 5LW fivecylindeted 94-b.h.p. oil engine is standard equipment with no alternative power unit, and a David Brown five-speed overdrive-top gearbox is incorporated.
A hypoid-bevel driving axle is used, and vacuum-hydraulic braking is standard. The example to be exhibited has been built for Peter McCallum and Sons, Ltd,, Bannockburn, and will have a 21-ft. platform body.
Double-drive Bogie
Of the two eight-wheelers to be demonstrated by Atkinson, one—for Holt Lane Transport, Ltd.—has a standard specification, with 6LX engine and air brakes, but the other, which is for G. A. Sinfield and Son, Ltd., has a double-drive rear bogie with hydraulically operated third-differential lock. The hydraulic actuation is necessary because the chassis has vacuum-hydraulic braking, and therefore no compressedair supply.
To avoid having to install an airpressure system specifically for operation of a conventional third-differential locking mechanism, it was decided to develop a hydraulic method of actuation, using Lockheed components.
It is believed that this is the first time that such a system has been dvolved for a commercial vehicle. The hydraulic circuit is self-contained and makes a neat installation. Like the Bass eight-wheeler, this chassis has the new David Brown 657 gearbox,