A New Sturdy Two-tonner in Hilly Country
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The She glex DL-type Chassis, Which Has Recently Undergone C:onsiderable Modification, Proves to be a Solidly Constructed Machine Capable of a Good Performance
"LIOR many years Shefflex chassis have been known as being solidly built and capable of giving long service. In recent months, important modifications have been made, one of the outstanding results being enhanced accessibility of the engine for decarbonization purposes. Our road test was carried out on the new 2-ton DL model, the chassis we tested being actually the second of this kind to pass through the shops of Shefflex Motors, Ltd., Tinsley, Sheffield, and it had only done some 75 miles prior to the start of our trial.
Before describing the test we may as well outline the recent modifications. The engine has been changed and is now a .four-cylindered Dorman of 85-mm. bore and 140 mm. stroke with a Ricardo-type detachable head of the turbulent pattern, . stainless-steel exhaust valves, nickelsteel inlet valves and thermo-siphonic circulation with a belt-driven impeller ; the fan also is
belt-driven. The crankshaft runs in three bearings, the same remark applying to the camshaft. The submerged oil pump is driven by an inclined shaft from the camshaft. On the off side of the engine are the carburetter, 1nagneto and dynamo.
A fabric-faced cone clutch is employed in conjunction with a massively proportioned stop. Our comments upon the operation of this component will be found in a later paragraph. A four-speed, four-point-mounted gearbox takes the drive, which is conveyed by a Hardy Spicer propeller shaft to the overhead-type worm axle.
Reverting to the subject of our road test. The vehicle—for the chassis was equipped with a tipping body and cab—was ready for delivery to a customer, who had specified a narrow-width cab to permit the carriage of long loads on each side of the body. This cab gave rise to a large amount of noise, but as our test concerned only the Sheffiex chassis, this element ' was not considered in our judgment of the machine. The vehicle weighed 2 tons 8 cwt. 2 qrs. unladen; this is considerably above the average for the model, owing to the type of body and the tipping gear insteled.
Around Sheffield there are many severe hills, all, more or less, difficult and capable of subjecting every component of a chassis to a gruelling test. One of the most trying is Jenkin Road, leading to Higher Wincehank, Sheffield. It commences with a gradient of 1 in 10 immediately after a right-angle bend, followed by 1 in 8, 1 in 7, 1 in 541 and a final section of 1 in 10, being in all 11 mile long. This hill cannot be rushed.
B44 Our ascent began on third gear from the corner, and second gear sufficed for a long portion of the climb until we reached the section of 1 in 7, On the worst section of the gradient the engine was not quite on full throttle and pulled manfully all the way up the slope.
At the top of the bill it was found that the water in the radiator had attained boiling point. This was due to the initial stretch of the fan and impeller-driving belts causing slip. When this matter had received attention the working of the cooling system was satisfactory and the normal water temperature during the rest of the day was 164° F.
During the climb halts were made and we found that a restart could be effected or the gradient of 1 in 10 on second gear, whilst the engine and clutch proved well up to the work of restarting on the 1-in-5 gradient, The fabric-faced cone clutch required moderate pedal pressure for disengagement ; it gave rise to no " bucking " of the chassis and showed no tendency to slip.
Once the operation of the stop had been learnt gearchanging was easy, and a feature which conduced to this was the butterfly adjustment for the idling position of the accelerator pedal; it enabled the tick-over speed to be set nicely, either for cold or hot conditions.. This could be done either when the driver was in his seat or on the ground. After the hill-climbing test we returned to the works and having assured ourselves that the fuel tank was empty, a measured gallon was poured into it. From Tinsley a hilly route was taken on the road to Worksop and 011erton. The gallon sufficed for 10.4 miles, which were covered in 27 minutes. The route involved the use of third speed on four occasions, and second speed once, whilst one enforced traffic stop required the use of all gears for getting away from rest. The conditions were arduous and such as might be anticipated only in a few hilly parts of the country.
A second gallon was poured into the tank and this, over more level country, was sufficient for 13.4 miles— covered in 36 minutes, involving two changes down to third gear and no stops. These conditions were representative of comparatively easy going.
As a basis for the figures shown in the accompanying panel, we have taken an average consumption of 11.9 m.p.g., which is the mean of the two previously quoted rates of use of fuel.
On level roads in the vicinity of Worksop, the topgear speed range proved to be 5 m.p.h. to 42 m.p.h.
The engine, which is of the " pulling " type, as opposed to one of high "revs." required only a small amount of care in the use of the ignition control at low rates of revolution. A little experience in the handling of this control—working laterally upon the dashboard —enabled improved acceleration to he obtained up to about 20 m.p.h. on top gear. The need for gear changing at low rates of revolution was pleasantly small, but, of course, improved get-away could be obtained by the use of the indirect ratios.
Owing to the noise due to the coachwork difficulty previously mentioned, it was not possible accurately to form an opinion upon the degree of silence attained in the functioning of the gearbox.
'Braking trials were carried out on a first-rate stretch of road, which offered a surface of the roughened type, that gave rise to no trace of skid, however fierce the brake applications. Bath hand and foot-operated brakes take effect in the drums of the rear wheels. They worked smoothly and without shriek. A Mareill vacuum-servo device reduced to extremely small proportions the amount of physical effort required. To obtain the best result when using the hand brake, a fair amount of strength was needed.
Worm-and-segment steering is employed. The gear ratio is fairly high, there being only 11 turn of the wheel from full right lock to full left lock. This type of steering proved easy upon main-road work, but rather stiff for inanceuvring.
Conventional semi-elliptic springs are used for fore and aft suspension, and these gave very comfortable riding; there was no tendency to pitch or roll. Frame flexion did not appear to set up any difficulties with regard to the engagement of the gears.
Our inspection of the chassis, subsequent to the test, showed that the interests of the user have been fully studied in the direction of accessibility. For example, the engine is carried upon two angle-section members, being located by four bolts. When the front crossmember of the chassis has been removed—the work of a few moments—and the clutch disconnected, the entire engine can be slid out forwards.
The gearbox, being separately mounted and slung below the frame cross-members, can be dropped after the disconnection of the transmission line at both ends, and of the selector controls ; the differential can be removed upwards, so that the three main assemblies of the chassis can be dismantled in a comparatively short period of time.