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-but GAME Road Test Albion Chieftain Super Six Scammell 18-ton-gross artic
By John F. Moon,
IT is understandable that national pride should make Albion products popular with Scottish operators (Albion quality, of course, makes its products popular all over the world for that matter, including the U.S.A. and Asia) but what is surprising is that hauliers living in such a relatively mountainous country as Scotland should prefer the low power-to-weight ratio frequently encountered with Albion vehicles. However, there is no getting away from the fact that small-engined Albions have been popu
lar in the land of the haggis for a great number of years.
This being so, it is not all that surprising to find that one of Albion's more popular tractive units has an engine of only 106 net b.h.p. output despite its gross train weight rating of 17-75 tons, giving a designed power-to-weight ratio of fractionally under 6 b.h.p. per gross ton_ This is the CH17TR Chieftain Super Six, with Scammell automatic coupling gear and Leyland 0.370 6-075-litre diesel engine. Tests made with this model show that it has, by normal Albion standards, a rather heavy fuel-consumption rate. This is certainly so when compared with the figures I obtained in 1960 with the Albion four-cylinder-engined version (CH7TR) which remains in production and which• gave a fuel figure of 12-5 m.p.g. at 27.75 m.p.h. average speed over the same 20mile route along which the Leylandengined version gave 9-9 m.p.g. at 34 m.p.h. average speed.
Admittedly, the six-cylinder tractive unit was cruised at 40 m.p.h. or so, compared with just over 30 m.p.h. for the four-cylinder model, but even allowing for this it is obvious that the Albion 5.5-litre system has adequate capacity for this engine, particularly as the climb was made with a following wind for most of the time. The minimum speed during the ascent was about 5 m.p.h., whilst the lowest ratio used was second, this being engaged for four times all told, the total time of use being 7 min. 30 sec.
The minimum speed and prolonged use of second gear indicates that this Leyland-engined model is probably not as good a hill climber as • the Albion-engined version, because during the 1960 tests the lowest speed recorded during this climb (which was made in an identical ambient temperature) was 7 m.p.h., and second gear was used for 6 min. 16 sec. only. The Leyland engine, however, was not being unduly overworked (as shown by the absence of exhaust smoking) whilst, when making the climb with the Albionengined outfit, slight exhaust smoking had been noted when running on the governor in second gear.
Maximum gradient ability was tested on Murrayfield Drive, the gradient of which is 1 in 5. While facing up this slope, the tractive-unit handbrake was shown to be not powerful enough to hold the outfit, even when applied with the footbrake held on, whilst the semi-trailer brakes when put on by use of the hand valve in the cab were not powerful enough either, although the semi-trailer parking brake was powerful enough when helped on by use of the foot brake. A bottom-gear restart was just possible with deliberate slipping of the clutch, but this get-away was made difficult because the engine refused to idle when facing up the hill, probably due to the injection-pump rack falling back.
Facing down the hill the tractive-unit handbrake and the semi-trailer brakes were shown to be powerful enough to hold the outfit, although the footbrake had to be applied first in order to get -the tractive-unit handbrake to hold. Restarting in reverse on this gradient proved impossible, reverse ratio being slightly higher than bottom. I would say that for normal purposes, when running at the Albion recommended gross train weight, slopes of 1 in 6 would be about the maximum on which restarts could comfortably be carried out in either direction. Of course, overloading would naturally mean that even 1-in-6 gradients are beyond the ability of the engine if stops have to be made on them, Five Fuel Runs As can be seen from the results detailed in the data panel, five fuel-consumption runs were made with this outfit, three while fully laden. The first was carried out over my usual Albion test course, which is 20 miles long and lies between Buchlyvie and Stirling. Half of this distance is of an undulating nature, whilst the rest is level, and the conditions approximate to those likely to be found on any normal main road in Britain.
I cannot help feeling that had the Leyland 0.400 125b.h.p. diesel been selected for this tractive unit, a far better fuel figure would have been forthcoming; this statement being based on the fact that an Albion Super Reiver rigidsix tested over the same route in 1961 (and powered by the 0.400) gave a fuel figure of 12-3 m.p.g. After all, whilst the use of a small engine can give good economy up to a certain gross weight, above this weight figure the engine has to work too hard to give good fuel results.
The two short-distance laden fuel tests were made over a 5-mile stretch of undulating dual carriageway in the -Glasgow area, and from these it will be seen that there is comparatively little difference between the consumption rates when cruising at around 30 m.p.h. mark and when observing a maximum of 40 m.p.h. This same stretch of
road was used for the two unladen runs, which w46re made with the semi-trailer attached at a gross weight t3f 5 tons 18 cwt.
Acceleration tests showed the six-cylinder engine to give the outfit a slightly brisker performance than was obtained in 1960 with the four-cylinder artic, the time taken to reach 30 m.p.h. from a standstill being 7.5 seconds bett r, whilst the time between 10 and 30 m.p.h. in direct drive (fifth gear) was 3 seconds better. Although a long, fiatF piece of road was used for these tests it was not possible to reach 40 m.p.h. comfortably in each direction, so times lwere not recorded up to this speed. When making the di ect-drive runs the engine and transmission were quite smo th when pulling away from less than 10 m.p.h.
Checks on the gear speeds showed that the following figures were obtainable in each ratio: 3, 7, 13, 22, 35 and 45 m.p.h., and the spread of ratios undoubtedly suited the engine's characteristics well and made it possible to get the optimum performance.
Despite the low engine power, the Chieftain Super Six tractive unit is not at all unpleasant to drive, although energetic use has to be made of the gearbox if the vehicle is to be kept moving at a reasonable pace. Furthermore, because of the need to keep the engine revs high when in the indirect ratios, the cab is not exactly quiet to travel in. A quilt over the engine cowl would probably help to reduce the noise level.
The ride is not too bad for a short-wheelbase tractive unit; but pitching is fairly prevalent, as is to be expected. With the semi-trailer empty, the ride does not appear to* deteriorate too badly. When travelling normally the Chieftain steers quite well, but prominent road bumps and harsh braking do affect the steering to a certain degree. Indeed, the front-spring wind-up probably accounted for some of the instability when making the braking tests, and I understand that attention is to be given to this point in the very near future.
The air-hydraulic braking system is a vast improvement on the vacuum-hydraulic system of the four-cylinder vehicle, and the braking is entirely proportional to pedal effort. However, 1 did have an opportunity of driving the unladen outfit on wet roads, and in this condition it did not feel too safe.
The Albion Chieftain Super Six tractive unit as tested, but less spare wheel, has a list price of £2,010. The Scammell 25-ft. semi-trailer which was used for the tests costs £655, including the flat platform body. Thus, for an outlay of less than £2,700 the purchaser of this articulated combination obtains a well-built vehicle capable of carrying 12 tons under most normal haulage conditions, but with below-average fuel economy. However, it is not likely that any other tractive units with this size of engine, or smaller, would be any more economical and so, taken in this light, the Chieftain Super Six shows up quite well.