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ALTHOUGH it has been known for two years that the builder of Foden goods vehicles had entered the field of passenger machines, only those intimately connected with the company were aware that the prototype, effectively disguised as a goods vehicle, was running some years ago. It was in our issue dated August 31, 1945, that a full description of the new passenger chassis was given.
With the concern's extensive and successful experience in the design and manufacture of heavy goods vehicles, it is not surprising to find that the passenger chassis is an engineering product of exceptional merit. So far as the power unit is concerned, the choice is given of a Gardner 5LW or 6LW oil engine. The vehicle which I recently road tested was equipped with the larger unit.
It has a bore of 4i ins, and a stroke of 6 ins., the six cylinders giving a total piston-sArept volume of 8.4 litres. It develops 105 b.h.p. at 1,700 r.p.m., has an R.A.C. rating of 43.5 h.p., and produces its maximum torque of 345 lb-ft. at 1,100 r.p.m. It is of the direct-injection type, the Gardner multi-hole sprayer discharging fuel into a dished piston-crown4 Insulating Engine Vibration The three-point flexible mounting for the engine is particularly effective in insulating engine vibration from the frame, a feature which assumes some importance in a passenger vehicle. Engine removal in the Foden is carried out by running the unit forward on a suitable wheeled jack, the front cross-member of the frame being easily removable.
A 15i-in.-diameter single-plate clutch takes the drive to a four-speed gearbox, and in the case of the vehicle I tested there was an additional super-low ratio, which gives approximately double the normal low-gear reduction. From my experience, however, I should say it would have to be an outsize in hills that would call for its use.
From the gearbox the drive is taken by a two-piece 34 Hardy-Spicer propeller shaft, each section having a sliding end to eliminate end thrust. The rear end of the first shaft is carried on a ball bearing, which is rubber-insulated from the cruciform-braced cross-members of the frame. A one-piece steel-alloy drop forging is employed for the rear-axle casing, the underslung worm drive of which is offset to the near side.
The bed of the front axle is of high-tensile steel, and the king-pin load is taken on taperroller bearings, with ball and roller bearings supporting the road wheels on 21-in-diameter swivel axles. There are 11 leaves, 3i ins, wide, in the front springs, and 14 leaves of the same width at the rear Respective eye centres are 4 ft. 2 ins. and 5 ft. 2 ins., both sets of springs having machined backplates.
Both axles are provided with Luvax hydraulic pistontype shock absorbers, and rubber pads are introduced to prevent the axles from meeting the frame members Front and rear brakes are of the Foden two-leading. shoe pattern and are hydraulically operated. There is an oil booster which gives a steadily progressive and compensated boost to all wheels, according to the degree of pressure applied to the pedal. As is usual practice, the hand brake takes effect on only the rear wheels; the linkage is mechanical.
The speedometer, clock, oil tell-tale and horn buttons are mounted in the centre of the steering wheel on a panel, which is, of course, located independently of the wheel.'
One of the outstanding features of this chassis is the cruciform construction of the main frame, which gives maximum rigidity and resistance to torsional stress. -Indeed, the whole chassis conveys an impression of immense strength I will now deal with its performance on the road The weighbridge showed DS that the gross weight was 9 tons 9 cwt. 3 qrs., to which must be added 2i cwt representing the weight of the driver and observer While the chassis was on the weighbridge, the fuel tank was filled to the top of the spout. The object was to refill to the same level on our return, having obtained a fuel-consumption figure embracing all the tests and the total mileage covered during the run.
Before leaving London for Sandbach, I mapped out a fairly stiff course on part ot which many hundreds of Army drivers were trained and tested during the war. Short Of introducing real cross-country terrain or freak hills, it would be difficult to devise a more strenuous trip for a normal production passenger-vehicle chassis, but I was soon to find that the Foden would have welcomed something even stiffer.
The first leg of the journey took us through Congleton to Dane-in-Shaw Bank, a climb of about mile, with a maximum gradient of approximately 1 in 5. Not being quite certain of our bearings, we found ourselves well towards the summit before we realized it was the test hill that we wanted. In returning to the foot, I discovered that the brakes were something above the average.
The hand brake, far too often, is looked upon more as a means for holding the wheels during parking; but here we had one that was capable of pulling up the vehicle from 20 m.p.h. on a 1-in-5 downgrade within a distance that would not disgrace some foot brakes. It may be mentioned that the total frictional area of the facings-701 sq. ins., or 72.9 sq. ins, per ton gross weight as tested—is somewhat exceptional.
Small Temperature Rise
Having regained the foot of the hill, noted that the atmospheric temperature was 52 degrees F., and the cooling-water temperature 140 degrees F., we started the climb on What was a second-gear stretch. For the whole of the ascent the road speed varied between Id m.p.h. and 12 m.p.h., first and second gears being used alternately according to the grade. For a short distance we reached 15 m.p.h., but Dane-in-Shaw Bank gives little relief to an engine from start to finish.
The climb took 4 rnins. 10 secs., but as the distance covered is not known precisely, I cannot give the average speed. A rise in cooling-water temperature of only 15 degrees F was registered, which speaks well of the cooling arrangements.
It was unfortunate that we failed to keep strictly to our routed course, as we missed a tit-bit of a climb, but it is probable that the Foden was quite as disappointed as ourselves!
From the top of the hill—about 1,000 ft. above sealevel—we made a circuitous route, and, again passing through Congleton, we now took the A54 road towards Church Hulme. We soon found a stretch of road suitable for braking and acceleration tests, with a slight rise towards the end of the outward run. This rise caught the Foden at between 25 m.p.h. and 30 m.p.h., as is shown in the figures obtained for acceleration.
From 0 to 30 m.p.h. and passing through the gears, the vehicle took 30 secs. in one direction, and on the return 25 secs., gear changing being carried out with full respect for the gearbox. From 10 m.p.h. to 30 m.p.h. on " top " took 38 secs, and 31 secs. respectively, the engine and transmission giving a smooth and propressive pick-up.
I was promised some exceptional figures for braking, and they were obtained. I usually ignore stopping-distance tests in connection with the hand brake alone, but, having had previous experience of the effectiveness of the Foden's brake, I was interested to see what figure could be obtained. On the first run the measured distance from 30 m.p.h. was 81 ft., and on the return 73 ft., giving a mean figure of 77 ft., representing an efficiency of about 39 per cent. sidered impossible of attainment. From 30 m.p.h., results of 33 ft. and 41 ft. respectively were obtained, the mean figure showing a degree of efficiency of about 80 percent.
The surface was gravel-covered tar macadam, and on all but the last foot-brake test the vehicle came to rest with the rear wheels about 1 ft. 6 ins, out of line with the front. This was, no doubt, caused by a slight lack of compensation due to the brake facings not having yet settled down evenly in all the drums. The run back to Sandbach was covered at a smart pace, as a comfortable gait for the Foden is about 45 m.p.h. I found the machine nice to handle, excellently sprung, as stable as a rock even when cornering fast, and free from transmitted vibration.
On replenishing the fuel tank, I found that the chassis had consumed 4.3125 gallons for a total distance of 40 miles. The fuel-consumption figure thus worked out at 9.04 m.p.g. on a journey which embraced all the tests, and included a number of really useful climbs.
There is no doubt that, in its passenger chassis, Fodens, Ltd., has a machine that will add to the prestige that the company has built up from its range of goods vehicles.