TESTING THE LATEST CROSSLEY
Page 52
Page 53
Page 54
If you've noticed an error in this article please click here to report it so we can fix it.
DELTA 4-TONNER in Hilly Country
A Hard Day's Work Reveals Excellent Road Characteristics. Ease of Handling arid Economical Running Are Notable Features of a Good All-round Performance
WHEN we took over the Crossley Delta 4-ton chassis for road test we were told by the Crossley concern to take it anywhere and to drive as hard a8 possible. Such an instruction bears the stamp of confidence and we can testify, after submitting the vehicle to an exceedingly strenuous day's work, that such confidence was not misplaced.
Amongst other things we climbed The Snake—a hill nearly three miles long—in second gear, averaged the maximum legal speed for 20 miles over indifferent roads, and ascended another long hill with a maximum gradient as steep as 1 in 4. Despite such strenuous work, the fuel consumption worked out at over 84 gross ton m.p.g.—a good figure for a substantially built chassis of moderate carrying capacity.
Our impressions at the conclusion of the ran were quite favourable, and it is clear that the Crossley concern has evolved a machine which should find favour with both large and small operators. The chassis tested was one of the long-wheelbase (14-ft.) models with forward control . B3S and 34-in.. by 7-in. tyres and an auxiliary gearbox providing eight speeds altogether. With the auxiliary ratio of 1.96 to 1 in operation, the lowest gear provided is 66.4 to 1; consequently it is able to negotiate practically any hill, in this country, on which it is possible for the tyres to obtain an adequate grip.
As has already been mentioned, we successfully negotiated a hill having a gradient of 1 in 4, and as we were able to use the second gear (in conjunction with the auxiliary ratio) it is apparent that a driver should not experience difficulty in making a restart on any acclivity with a " made " surface.
Although capable of such arduous work, the Delta chassis is also suitable for long-distance main-road haulage, and from our consumption figures it should be apparent that economy of operation would be a prominent characteristic. It might here be mentioned that the figure of 11.2 m.p.g. obtained dnring our test represents the overall consumption on a 50-mile journey which included climbing The Snake, a 12mile tour into • the hilly district around Hayfield and a prolonged spell of stopping and starting, during wtich the acceleration and braking figures were obtained.
The steering is light and accurate, the clutch and brake mechanisms respond to delicate movements of the pedals, and gear changing is a simple matter.
The suspension, too, appears to be well suited to the requirements of the chassis and gives the driver (who, in the forward-control position is situated immediately above the front axle) a comfortable journey, whilst the rear suspension, although by no means hard, does not allow notice
able rolling or swaying. .
Considering the fact that the engine has a swept volume of only slightly more than 34 litres, the acceleration is remarkably good. In
top gear 30 m.p.h. can be attained from 10 m.p.h. in 45 seconds, whilst the normal cruising speed of 25 m.p.h. can be reached from rest in under 40 seconds—good going for a vehicle having a gross weight of over 74 tons.
As the hill-climbing capability of
vehicle is exactly related to the performance, as shown by its capacity for acceleration, we might here interpose a few remarks concerning the performance of the Delta during a climbing test. One hill used for this performance was The Snake—a pass running from Glossop to Sheffield over the Pennine Range.
The gradient is not particularly evere, but the hill is some three miles long, with an average rise of .1 in 19. There are several places, however, where the gradient is between 1 in 13 and 1 in 14. The Crossley made a steady climb throughout in second gear, completing two miles of the steepest section in 11 .mins. 45 secs.—giving an average speed of slightly more than 10 na.p.h. On the steepest sections there was no doubt as to the capacity of the engine for maintain ing speed without recourse to a lower ratio.
For most of the time the engine governor was restricting the speed, so there was clearly power in hand. Temperature readings showed that during average running on reasonably level roads the mean engine temperature worked out at about 160 degrees F. After climbing The Snake non-stop, there was no sign of boiling, he thermometer registering a cooling-water temperature of 196 degrees F.
Our second hill-climb test was carried out on a by-road near Hayfield. There, the Tapley meter recorded a gradient of 1 in 4 when we stopped to engage the auxiliary gear. An easy start was made in the first speed of 66.44 to 1, so we tried second gear (with the auxiliary ratio in operation) and obtained an equally smooth get-away ; the ratio in this case was 40 to I.
The narrow lanes in this district gave us an opportunity to assess the value of the steering lock and the brakes. On several occasions corners which appeared to be too sharp to be. negotiated in one lock were easily rounded without the need for reversing, whilst the brakes were always equal to the occasion.
Thanks to the vacuum-servo, the pedal pressure required for an emergency pull-up is very light, little heavier, indeed, than that of many private cars. Even on the 1-in-4 section of the hill used for our climbing test we did not experience the slightest qualm concerning the capacity of the brakes to hold the vehicle. A further point we noted is that both hand and foot systems are quite effective when the vehicle is moving backwards ; the rear brakes, applied by the hand lever, are just able to hold the vehicle from running backwards on a gradient of 1 in 4.
Slung across the chassis amidships is a vacuum tank from which the B39
is withdrawn by an exhauster built into the engine unit. Even without the engine running, the pedal can be applied about a dozen times without bringing the vacuum tank up to normal pressure, so that in the event of the engine stalling, when coasting down a hill, adequate servo action would be available for at least eight applications of the pedal. Under the most favourable Qircumstances the wheels just fail to lock.
Before concluding it might be opportune to record our impressions of the engine. The unit is of distinctly moderate cylinder capacity, but as it possesses a high volts metric efficiency the power output is satisfactory for a medium-sized vehicle such as the Delta chassis. The maximum power output of 50 b.h.p. at 2,150 r.p.m. is developed without smoke from the exhaust, and there seems to be no limit to the length of time during which full power can be used—our hill-climbing test proved this point.
Another factor, the maximum. torque (200 lb.-ft. at 1,200 r.p.m.), is sufficiently high to enable one to maintain the cruising speed on an undulating road, thereby precluding constant gear changing.