THE VULCAN LIGHT )ILER TESTED
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/N faking over for test this new Vulcan model, we had not a feeling of boarding an unknown vehicle, for the chassis follows lines faMiliar to us in many other VuIcans we have tested and driven in the past few years. The engine is the Dorman-Ricardo type 4DS, which has been on the market long enough, and fitted to road vehicles in
sufficient numbers, to establish its good name. Even the body is a Vulcan product, solidly and simply —although not heavily—built, and embodying practical ideas.
We have had a lot of experience of Vulcan products and works methods, and feel that we ought to interpose a note on what seems to us to be a sensible manufacturing policy —and is, no doubt, the reason for the steadiness of Vulcan sales during two or three difficult years. This policy is nothing more than "to adopt, to adapt and to improve," and expresses itself at Crossens in the use of only well-tried components, and in improving and lightening them rather than turning to unknown units. A new Vulcan type is a known quantity, not elaborate in equipment, but reliable in every component and honest in performance on the road.
Accessible Brake-shoe Adjustment.
On a new Vulcan you may not find automatic brake-shoe adjustment, hut you can be certain that the adjustment is accessible and that no Lrake cross-shaft will be unfairly stressed in torsion. The instrument panel may not be streamlined, but the wiring at the back of it will be easily reached. The cab may not have the curves of one made from mass-produced pressings, but if it be a forward-control vehicle you may. rely upon the provision of quickly detachable wings and floorboards with rattle-proof mountings.
An important contributory factor in the company's policy of design is that all major components are made at the Vulcan works. In the 40-DHN, for instance, the front axle, rear axle, steering gear, clutch, gearbox, propeller shaft, brakes and frame are Vulcan built, with the exception of such items as the David Brown worm and worm wheel for the back axle, and the Marelli servo for the brakes. In the petrolengined models the engines themselves are designed and built by the Vulcan concern.
Robust Design.
The 40-DHN looks and no doubt is very robust for a 2-tonner, but it is not unduly heavy, the lorry weight in licensing trim being only tons 0i cwt. This brings it within the class for which the legal speed limit is 30 m.p.h. , The comfortable maximum speed on a level road is about 36 m.p.h.—not high even for an oiler.
But we would not recommend a higher back-axle ratio because 6.5 is a ratio which makes the lorry capable of taking many main-road gradients in its stride at a speed not much lower than its normal cruising speed (30 m.p.h.). This eliminates a lot of gear changing and on a long journey helps to keep up the average speed.
Quiet Cruising at 30 mph.
The vehicle cruises very quietly at :30 m.p.h., and is noticeably reluctant to lose speed for slight gradients. Another point is that in moderately hilly country there seems to be a large proportion of hills that can be climbed in third gear at 20 m.p.h. To slip into third gear is quickly and easily done, and the hills are climbed without material loss of way.
The net result of this relationship of load, gear ratio and engine-torque characteristics is that on a direct allday run one can maintain a high average speed of about 26 m.p.h., or only 10 m.p.h. less than the maximum speed.
Our fuel-consumption run was fairly conducted, and the figure of 16.4 m.p.g. is satisfactory. The speedometer was checked for speed and distance readings and found to be accurate.
The acceleration characteristics of the loaded vehicle are shown in an accompanying graph and are adequate even for town and short-distance work, despite rather a long pause when changing to each higher gear. This long pause is inevitable with an oil-engined chassis, and nothing short of a massive flywheel brake will eliminate it.
Excellent Performance on Hills.
On hills, for instance, the capability . of the 40-DHX is of a higher order than the level-road speeds would Ouggest. On a 1 in 6 gradient near London we could maintain nearly 2,000 r.p.m. in first gear with full load. On Parbold Hill, in Lancashire, our minimum speed was 6 m.p.h. in second gear—the gradient being about 1 in 8. We climbed the I mile of this hill from a standing start in 41mins., averaging 10 m.p.h., which, from past experience of the gradient, is quite satisfactory. Our radiator temperature at the summit was 168 degrees F. against the normal temperature for that day of 144 degrees F., when the air temperature was 45 degrees F.
If changing up be a slow process, changing down, at any rate, is quick, for the acceleration of the free engine is rather above the average. This fact, combined with the easy gear change and the light and smooth clutch action, facilitates manoeuvring on hills, in loading yards and in traffic.
High Torque at Low Speeds.
Another good feature in this regard is the steam-engine characteristic of the low-speed torque. On the level it is possible to pull away in top gear from 5 m.p.h. slowly but without labour or roughness, and on a hill you can change down to third gear at as low a speed as 12 m.p.h., and to second at 5 m.p.h. without losing steady drive. First gear should only be required on hills of exceptional severity, and the change-down can be easily made.
The Vulcan clutch is good. and the company has an ingenious way of ensuring lubrication of the spigot and splines. The constant-mesh-pinion of the primary shaft of the gearbox is drilled radially-in the 'valley between two teeth, the whole connecting with an axial drilling forward to the clutch spigot, there being another radial hole to the clutch splines. The working of the constant-mesh gears pumps oil to the spigot and splines, and excessive lubrication is prevented by limiting the size of the apertures. Also, two oil throwers are provided as a final precaution against oil reaching the clutch facings.
Powerful Braking.
A new brake layout has been evolved which gives excellent results. The single four-wheel system is actuated either by the 1Vlarelli vacuum servo or by the hand lever, and the latter is long and convenient. An exhauster and reservoir are fitted, the latter being big enough, we found, 10 provide six strong and three moderate vacuum applications after the engine has been stopped.
An accompanying graph shows that the braking results are above the average for any commercial vehicle, light or heavy, and the layout must be good, because on a gradient of I in 6 we could easily stop the vehicle and hold it with the foot brake, even when the servo was inoperative ; it was still easier to hold it with the hand lever.
The worm-and-wheel steering gear is comfortable and positive, and the turning circle quite small enough for any class of duty. The springing is good and the load distribution seems to be about right. We always reckon that if we can make copious pencil notes in comfort while travelling on a. normal road the springing is fairly good. The front springs are 42 ins, long and 2 ins, wide, and the rear springs 52 ins long and 21 ins. wide.
B2S The vehicle is adequately tyred for its weights. There is no lateral instability when cornering at rather excessive speed. Looking over the machine after our run we noted that the strong elliptical fuel tank is accessibly fixed on the off side of the frame and is easily removed from its secure mountings ; the vacuum reservoir balances it on the near side. We also noticed that a new type of spare-wheel carrier, under the tail, is now fitted. The mounting is robust, the screw is easily reached and if slack would not cause undue rattling of the wheel.
Improved Cab Design, The new Vulcan cabs are much improved in appearance, and of particularly strong and practical construction. The roof has a trap door, there is a large glass light in the rear bulkhead, and the Auster one-piece screen is hinged at the top. The driver has a drop window and his mate a sliding half-window. A point about the control of the engine is that the electric starter will not engage unless the heater plugs are switched on. The hand brake and gear lever are on the left, giving the driver a free entry.
We do not appear to have been very critical in our review of this chassis, but that is because the de'sign and performance are sound. The lorry is not ontstanding in matters of top speed or acceleration, but is satisfactory on all counts, and particularly strong as to brakes. It should give reliable service over klk long period with low maintenance costs.