Arran Introduces a Petrol-engined 4-tonner
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T0 its range of .4-ton, 7-8-ton and 12-13-ton oilers, Arran Motors, Ltd., Welwyn Garden City, Hefts, has added a new petrol-engined model. This innovation follows the company's recent move into a modern and commodious new factory. The Arran AP6/4, as the new ' chassis is designated, is rated as a 4-tonner, and will be available in two wheelbase lengths, the unladen weights, with standard lorry body? being 2 tons 7 cwt. and 2 tons 9 OWLrespectively. It is equipped with a six-cylindered power-unit and a synchromesh gearbox, whilst the price is fixed at £495.
This is not an unattractive figure in view of the high-quality components incorporated, the sturdy construction, the up-to-date and well-thought-out design, and the fact that each chassis is erected individually and under the direct and personal supervision of the company's chief engineer, Mr. C. Kilburn, A.M.I.Mech.E., M.I.A.E., who has had an extensive experience of commercial vehicle manufacture With a number of the leading British makers. . Adequate Body Space.
In short-wheelbase form-9 ft. 101 ins. between centres—the standard body-length is 12 ft. With a 12-ft. 10,2-in. wheelbase, the figure is 15 ft., whilst a maximum of 16 ft. 3 ins, is possible without exceeding the legal limit. The frame height is 2 ft. 5 ins., in both cases, giving a platform height of 3 ft. 4 ins.
Composed of good-quality steel, the chassis frame has straight side members, measuring at their points of maximum section 6i ins. by 3 ins. by A in. These are braced by six sturdy cross-members, which. arc. secured exclusively by high-tensile-steel fitted bolts, that member which is in line with the front brackets of the rear springs being well gusseted to the longit udinals.
An Austin power unit is employed, to which is bolted a gearbox of the same make, the whole being supported at three points on rubber. Rated at 23.5 h.p., the engine has a bore and stroke of 3i. ins. and 4/ ins. respectively (3.4 litres), and develops 58 b.h.p. at 2,600 r.p.m.
Side valves are used, and, of course, the head is detachable. The induction system is of the hot-spot type. the manifold being fed by a Zenith down draught carburetter. Ignition is by coil and battery.
A single-plate clutch conveys the drive to the gearbox, which affords ratios of 4.35, 2.45,1.57 and 1 to 1. A long lever, Set to extend well forward, enables the changes to be made by a natural arm movement on the part of the driver.
From the gearbox, a two-piece tubular propeller shaft, incorporating three Hardy-Spicer needle-roller universal joints, and supported centrally by a spherically mounted roller bearing, transmits the power to the rear axle.
This is a Kirkstall component of the overhead-worm type, and of ample capacity for the vehicle in which it is incorporated. The half-shafts are fully floating and the final reduction is 7.5 -to 1. The wheels are of the eight-stud pressed-steel type and are shod with 32 by 6 tyres, twins at the rear. They carry brake drums of the largest practicable diameter and widths.
For expansion of the brake shoes by the pedal, the -Lockheed system is employed and operates on all four
wheels. Only the rear brakes are actuated by the hand lever. This is of the push-on type, and is unusually long to afford ample leverage.
The layout of the mechanical coupling between lever and hubs struck us as being of first-class design. ' The cross-shaft is 2 ins, in diameter and mounted on spherical bearings, whilst, at the rear hook-up, the final rods are pinned at their forward ends approximately in axial line with the springeyes.
Appearance Distinctive.
Reverting to the front of the chassis, an improvement in appearance has been effected by mounting the radiator vertically instead of • sloping it 'backwards as on the original Arraus. It is rubber mounted on a detachable crossmember, which also carries at its centre the front end of the engine.
This member has lipped ends, the projections resting on the frame side channels, which at this point contain box-section distance pieces to afford a rigid fixing where the members arc bolted together. Further stiffness to the front part of the frame is given by diagonal reinforcing pieces in the side channels near the rear engine feet.
The last-named, incidentally, are of aluminium alloy and extremely robust design. They rest upon rubber cushions on the tops of the main longitudinals. The whole assembly is so arranged that the complete engine, gearbox, radiator, etc., can be withdrawn forwards as a unit.
With regard to the suspension 825
system, each rear spring measures 4 ft. 2 int. between centres and contains 13 3-in, by izcin. leaves, whilst at the front, the length is 3 ft. 4 ins., the leaves number seven, and are in. thick and the same width as those at the rear. The four rear spring brackets are interchangeable, as are all the shackle pins. These, incidentally, are secured by locking bolts at both ends, in every case.
A cursory examination of the chassis brought to light a number of note worthy details. An encased flexible cable is used to make a neat connection between the accelerator pedal and the throttle-control gear. All the pedals are adjustable for height.
The batteries are mounted under the near-side seat, where they are accessible and as close to the starter-motor as possible. The large air-cleaner on the carburetter intake is outside the bonnet and thus draws air from the cab. Petrol is fed from the sidemounted 15-gallon tank to the carburetter by an autovac, mounted high on the near side of the dashboard. On the off side, the instrument board is mounted and tied to the column. This model is the third 4-tonner in the Arran range, the others being the well-known Perkins-engined machine, and the recently introduced Gardnerengined chassis. This last is equipped with the 4LK unit and is offered in two wheelbase lengths, the models costing £750 and £765 respectively. Both come within the 50-cwt. limit.
Readers who are interested should apply to the company for a new leaflet —just published—in which the main features of this 4-tonner, together with those of the Gardner-4LW-engined 7-8-tonner, are outlined.