HIGH PERFORMANC: in an Overseas Six-wheele
Page 16
Page 18
Page 19
If you've noticed an error in this article please click here to report it so we can fix it.
IN planning the Albion CX23 six-wheeled chassis, the designers have produced a vehicle which will operate without overheating under the most severe conditions, including climbing a 40-milehill, in areas where the day temperature often reaches 100 degrees F. The model tested was one of a batch at present being exported to South Afrita, and it will haul a trailer up the 40-mile gradient as part of its normal daily route.
The robust construction of the chassis and components is such that the vehicle should be able to withstand the rigours of operation over unmade roads and climb or descend long gradients without need for frequent maintenance. The 10.455-litre overhead-valve petrol engine developing 155 b.h.p. at 2,100 r.p.m., has a cast-iron crankcase and cylinder block, bolted together, and dry cylinder liners are fitted. Twin detachable cylinder heads each cover three bores, and the components, including the air compressor for brake Operation, are chain driven from the front of the crankshaft. An unhardened crankshaft is used in conjunction with white-metal bearings.
Air for combustion, and for the compressor, is drawn through a Visco filter, the metal plates of the filter being connected to the throttle pedal and revolving in an oil bath with movement of the pedal The engine fan operates in a cowl, bolted to the front of the power unit, and has a 1-in, clearance at the tips of the blades. The main air cowl is fixed to the radiator, and is connected to the fan section by a flexible canvas gaiter. .Located at the front of the engine, the coil and distributor are positioned in the air stream from the fan to give the maximum cooling.
Engine, clutch and gearbox form a unit, which is retained in the chassis by a single bonded-sandwich mounting from the front of the unit, and by an Albion bell-crank lever unit on each side of the clutch housing. The flywheel and clutch are totally enclosed.
B8 In the main gearbox, the highest two ratios are dog engaged, whilst the second, first and reverse speeds are engaged through sliding gears. Straight-toothed gears are used in the main and reduction boxes, the third ratio of the main box being in constant mesh. A short, sturdy shaft with mechanical universal joints connects the main and auxiliary gearboxes. The reduction box, operated from a separate selector lever, has a ratio of 1.84 to I, and direct drive.
Hardy Spicer jointed shafts are employed in the transmission between the reduction box and centre
axle and between the two overhead worm drives of the bogie. There is no third differential. Large fiat-based worm pots afford an adequate reservoir of oil for the final drives and give the required ground clearance for cross-country operation.
Twin inverted semi-elliptic springs attached to a dead axle have large ball-ended torque rods to
give the necessary articulation for tra.4ling over bad
surfaces. Brackets from the frame reft...ct excessive
movement of the wheels. All the brake rods of the bogie are also ball-ended. The brake shoes are cam-operated and the single wheels of the bogie, together with wide drums, ensure that the maximum drum area is exposed for cooling. This is an important feature, having regard to the operating territory, and I checked its efficiency.
After ascertaining the gross and distributed loads at the works weighbridge, a short detour was made to warm up before attempting to climb Gardner Street, situated on the outskirts of Glasgow. There was a slight hesitancy from the engine when accelerating during the first mile, but within 10 minutes from starting it appeared sufficiently warm to make the trial.
Starting on 1-in-7, the lower ratio of the reduction box was engaged in conjunction with second gear in the main gearbox, and the machine was driven away to climb to the top of the hill at maximum engine revolutions.
The driver then reversed down the hill to the steepest section, where the Tapley meter registered 1-in-41-. To move a large-tyred, high-axle-ratio vehicle weighing over 19 tons away from this point seemed to be a formidable task. Optimistically, the driver attempted to start in second gear, but this was too great a burden for the engine and transmission. When the lower ratios in both gearboxes were used, the machine pulled away smoothly and without trace of transmission, whip.
Regaining comparatively level ground, 1 drove at a smart pace to Strathblane. With the ample engine power, little time had to be spent in the intermediate ratios, and in second gear the vehicle could accelerate comfortably from rest on level ground. I found that the Albion could cruise smoothly and quietly at 30-35 m.p.h. The light controls and progressive braking made this a reasonably safe speed Because of the gear-tooth formation, there was rather more noise when intermediate ratios were engaged.
The longest hill I could find in the area was on the Strathblane-Stocklemuir-Drymen road, which skirts Campsie Fells. Although not a spectacular climb, the road rose steadily over three to four miles, the gradient reaching one in eight. I took the temperatures before starting the trial, obtaining an atmospheric reading of 56 degrees F. and a radiator top-tank temperature of 164 degrees F .100 1 found scope for gear changing on this part of the course and did not fail to get the utmost power out of the engine. Despite this treatment, the water temperature rose by only one degree—a good mark to the efficient cooling system. Axle temperatures, taken at the top of the hill, were 151 and 153 degrees F The engine and axle cooling arrangement are obviously adequate for much warmer climates than that of Scotland. • On the final part of the journey into Drymen, I drove against the brakes for a mile to test for fade by overheating. If there were any deterioration in efficiency, it was so slight that it could not be noticed by the driver Because of the expansion of the drums, there was slightly more pedal travel than before starting the test, but there was still ample pedal movement if required.
The brake tests recorded in the data panel were made on the road between Arnprior and Stirling. A brief period was allowed before starting the tests, to permit the drums to cool to a normal operating figure. The road surface, althouah level, was rather soft, and during all emergency brake applications the wheels locked over a considerable distance. Even so, the stopping distances of 54 ft. from 30 tn.p.h. and 22 ft. from 20 m.p.h. would be adequate for this class of vehicle. A notable point is that these stopping distances could be reproduced with hot as well as cold brake drums.
During the acceleration trials, second gear was engaged when moving away from rest, and then a rapid
change was made to the third and direct-drive ratios. To reach 30 m.p.h. from rest in 338 sees. with a vehicle weighing over 19 tons is no mean achievement, but this was the average time taken from a number of tests in each direction. "che ,flexibility of the engine is also demonstrated by the figure of slightly under 30 secs. for acceleration from 10 to 30 m.p.h. in top gear.
By the end of these tests we were almost into Stirling and faced with a long journey back to Glasgow. I made use of this journey by running a consumption test at Maximum speed between Stirling and Bucklyvie. This course was hilly and required frequent use of third and sometimes second gears. Wherever possible I drove at the maximum advocated speed--37-38 m.p.h.
A speed of 28.8 m.p.h. was averaged over the 18-mile journey and the fuel consumption was equivalent to 3.6 m.p.g. A second consumption trial was made between Drymen arid Ballock. This also was a comparatively hilly course for a consumption test and could be well defined as having less give than take. The maximum speed of 33 m.p.h. on this run gave a marked improvement in fuel consumption without any great loss in average speed-5 m.p.g. at 26.4 m.p.h. Operating temperatures taken at the end of the two consumption tests showed that the water had remained constant at 164 degrees F., and the axle lubricants had settled at 133 degrees F.
I would have taken the machine over a cross-country course, but, unfortunately, there is no proving ground in the Glasgow area, and the surrounding countryside does not afford a suitable surface for testing a heavily laden chassis.
To obtain an impression of the suspension efficiency, I drove over an unmade road surface at 20 m.p.h. and 30 m.p.h. This was the nearest approach I could find to overseas conditions. The large tyres fitted to the Albion smoothed out most of the potholes, whilst the remaining bump or rebound was effectively controlled by the springs. A corrugated surface failed to find a periotheity in the suspension.
The results of the 85-mile trials suggest that the
Albion is one of those vehicles which will be found operating, with satisfaction, in a large number of overseas areas for many years to come: The design of the chassis will earn praise by users in the warmer climes of the world, and trouble free operation should serve as a recommendation for sound British design
As a chassis, it j5 notable for the accessibilq to all parts requiring adjustment or other maintenance. Such items as brake adjusters are positioned externally of the frame, and oil or water filling orifices are well positioned and have large necks for easy use.
Another detail I noticed was the totally enclosed multi-pull hand brake. I found that with normal driving only half the lever travel was required to apply the brake fully. The designers have specified this arrangement to make allowance for when the drums have heated and expanded