A CUB OILER UPHOLDS the
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LEYLAND REPUTATION
0 UR first impression on leaving the Leyland Co.'s Ham works on board the Cub KG03 oilengined demonstration lorry on which this road test was conducted was that its six-cylindered power unit behaved more like a petrol engine than any oil engine we, have yet tested. It is quieter than usual for its type, it is singularly free from vibration and it accelerates with unexpected liveliness. The rate of consumption, however, is in keeping with oil-engine characteristics, but the impression of resemblance to the petrol unit is sustained by less
prcinounced ability to " hang on " at low engine revolutions.
The KG3 models are listed as 21tonners but, in view of the fact that they are habitually laden in excess of this figure and that, in the opinion of their maker, they are well capable of carrying 3 tons under normal conditions, ballast of this weight was employed for our test.
This model, even with a platform body, scales inore than 2i tons unladen, but its appearance does not suggest this—an important point, because it is actually capable of a speed of 40 m.p.h. Although by no means the most expensive chassis of its type, the Leyland Cub is fairly high in price. Quality of materials and workmanship, durability and numerous refinements are what the buyer obtains for his money, and it is in keeping with the policy, presumably adopted by the Leyland concern, that slightly higher first cost and a few extra pounds in taxation are of trifling importance to the operator who seeks trouble-free and lasting service.
It was, perhaps, the thought of the enviable reputation of Leyland products that induced us to put the Cub to a hill-climbing trial of unfair severity, namely a stop-and-restart test near the summit of Nightingale Lane, the steepest road ascent of Richmond Hill. From a halt where the gradient is slightly steeper than 1 in 5 the machine was just unable to regain sufficient speed in restarting to continue the ascent.
Had the recommended pay-load been carried or had the machine been equipped with the alternative lower back-axle ratio, no doubt it could have accomplished the task. As it was, a non-stop climb was subse quently made with complete ease at a minimum speed of between 4-5 m.p.h., and the machine wa successfully started from rest on a slope of 1 in 6.
Readers will have noted that our usual stop-andrestart tests are conducted on hills of no greater severity than this, and will agree, we are confident, that under normal working conditions a lorry rarely has to get away on a steeper gradient. If it works in harder circumstances, special provision must be made.
We did not spare the Cub in ascertaining its rate of fuel consumption. From Ham Common a circular course was chosen and was covered in three sections of 11.3, 10.8 and 12.3 miles respectively, on each of which half a gallon was consumed. Over the whole route of 34.4 miles the rate was equal to nearly 23 m4g.
The first section followed the main Portsmouth road and included the thick traffic of Kingston and the series of hills commencing at Esher and ending with that between Cobham and Wisley; all were surmounted easily in top gear, Cobham Hill being the only one that brought the speed down to appreciably below 20 m.p.h. The second section included Ripley, where we left the main road, and the long climb thence to West Horsley. Along the narrower roads between these two places consider ably lower speeds, with frequent use of third gear, were necessary.
The final stretch took us through Leatherhead, up the acclivity just beyond the town on the Hook road—this brought us down to third gear—and back, through Kingscon, the test tank becoming exhausted almost within sight of our starting point. The return is excellent in view of the fact that the engine is a "six," and the route may be regarded as representative of average running conditions.
in both acceleration and braking the Leyland showed up extremely well. A speed of 30 m.p.h. was attained from rest in 30 seconds. Averaged results of past tests of machines in the same class give 40 seconds.
The retardation tests demonstrated B29 that, from 30 m.p.h., the vehicle could be stopped in about 60 ft. Our ' corresponding actual average is 90 ft., whilst a theoretical analysis shows 64 It,
The foot brake deserves high praise and its efficacy should be at least proportional to its durability, in view of the large area of frictional surface per ton gross weight. It is of importance that, besides being effective, brakes should be smooth in operation. In this respect those in question were among the best we have ever tested. They afford a retardation that appears constant from the moment they are applied until the vehicle comes to rest. Thus, the minimum disturbance to the load and discomfort to the driver are caused, whilst skidding is not promoted.
Little advantage is afforded by using the hand brake as well, although this is quite serviceable for the purposes for which it is intended.
The machine is very light to steer and the steering lay-out affords just enough .self-centring action to relieve the driver of labour in straightening up after a corner. An inspection of the power unit revealed several interesting points, a number of them being of recent incorporation. The flat face of the cylinder heL7c1 gives a fiat-topped combustion chamber, whilst a deep cup is formed in the piston crown, into which the fuel is obliquely injected. The inlet valves are shielded; that is to say, a thin wall of metal protrudes from the underside of the head of each along the smaller circumference of the seat-bevel, for about a quarter of its length, concentric and parallel with the valve axis. Thus, when the valve is open, air can enter from, as it were, only three sides of the port. This creates turbulence, and, we were informed, greatly . influences the performance of the power unit.
Big-end difficulties have been n30 solved by designing the aluminiumalloy connecting-rod to bear directly on the crank-pin journal, there being no white-metal or bronze lining. The crankshaft is provided with bolted-on balance weights to each web. Unusual construction is found in the piston. The gudgeon-pin bosses are carried solely by struts projecting from the crown, holes in the skirt receiving their outer ends.
On the model we tested the standard fixed injection is employed, but if specified a control can be incorporated. A detail—important, none the less—that merits description is the spare-wheel carrier (illustrated on the
We were much impressed by the liveliness of the power unit. Our impression is corroborated by these acceleration curves.
preceding page). The wheel is mounted on a frame provided at its forward end with two rollers, which. run on rails mounted under the rear extremities of the chassis longitudinals. The back end of the wheel.
carrier is secured to the rear chassis cross-member by a bolt and hand
nut. Thus, the operation of shipping and unshipping the spare wheel requires little effort and is accomplished, with rapidity. • The chassis generally is of straightforward and conventional design,
and of first-rate construction; -the model is too well known for it to need description here. The appearance of the complete machine is pleasing, the proportions being good and the lines those of a thoroughbred. It is easy to drive, the controls, including the gear change, being light in operation.
As we remarked earlier, quality has not been sacrificed nor weight cut down to save a few pounds in cost and taxation, but the longsighted, prospective purchaser need not be deterred by these consi4Eflans ; the additional capital outlay involved is surely soundly invested.