TESTING THE FODEN RIGID SIX-WHEELER.
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Extraordinary Ton-mileage Results. Details Hitherto Not Available.
ONE of the latest and most interesting of the products of Fodens, Ltd, Sandbach, Cheshire, the well-known , maker of steam wagons, is the Foden rigid-frame six-wheeler. Brief details and an illustration of this were given in our issue dated May 24th, and particulars of some of the results obtained with this new model 'are now available ; also a few further details of 'the design, particularly as regards the semi-bogie arrangement of the rear wheels, for so far as the forward part of the vehicle is concerned it is in practically every respect similar to the latest model 6tanner to which we shall also make reference.
Two tests of particular interest were those which took place on the route Sandbaeh, Holmes Chapel, Knufsford and return. These tests were made under practically identical conditions, except for speed, which in the first test averaged 12.301 m.p.h. and in the second 17.272 m.p.h. The extraordinary feature is that the ton-mileage per cwt. of fuel was almost the same in the two cases, although one would have thought that an increase of speed of nearly 5 m.p.h. would have had the effect of greatly increasing the fuel consumption. The front-axle weight was 3 tons cwt. and the total back-axle weight 15 tons 3 cwt. 2 qrs., giving a gross load of 18 tons 11 cwt. 2 qrs. The net load was 10 tons 6 cwt., so that the tare weight of the wagon is 8 tons 5 cwt. 2 qrs. The following are the figures of the actual tests :— It should be pa iticularly noted that in the first test the ton-mileage per cwt. of fuel works out at 198.7, and in the
second test 190.6, giving a difference of under 9 ton-miles per cwt.
Now as regards the arrangement of the semi-bogie. Driving is effected only through the forward wheels of the bogie, through the medium of a long, powerful roller chain. It will be realized that with this form of drive it is essential to be able to adjust the chain tension, not only when the vdhicle is first built, but as wear occurs. Consequently, the forward axle, of the bogie must be able to move slightly in relation to the chassis, and a means for securing this is provided by the employMent of two adjustable radius rods, which also serve to convey the drive to the powerful frame brackets, which are dropped low, so that the radius rods are almost horizontal, this constituting a distinct ' improvement over those vehicles in which radius rods are carried upwards at a fairly steep angle so that the drive is more of a wedging action than a direct push.
ei Very stoat, single, sem"-elliptic springs are employed for the su ension of the bogie. Each spring is s ired at its centre by means of a link to a slipper working in horizontal guides carried indimmensely strong brackets attached tr the side members of the chassis frame. Short radius rods extend backwards from the forward bogie axle to the slippers, and a further pair of radius rods extends from the slippers to the rear axle of the bogie. Thus the position of both bogie axles is dependent upon the main forward radius rods taking the drive to the frame, and when the vehicle is running over rough ground it can clearly be observed that the spring slippers are afforded free movement.
It is the special slippers which take the whole of the weight of the rear portion of the vehicle and transmit it via the semi-elliptic springs to the bogie axles. The present platform space is 20 ft. long, but it is probable that this will be reduced to IS ft. in the production model.
This new steam-propelled chassis 'is easily capable of carrying 12 tons useful load. We actually saw it under test with over 11 tons and it ran with remarkable smoothness, even over a somewhat potholey road. Later it was mameuvred about in a confined area for our inspection, but without its /load; it was, however, easy to see that its control is almost the acme of simplicity, whilst easy riding over rough ground is permitted, as each wheel can rise 8 ins. above its fellows and is allowed perfect freedom, so that the bogie action, when the wheels are running over humps or into potholes, greatly reduces the hocks on the chassis.
The company is firmly convinced that everything points to the carrying of bigger loads in the future, despite the proposed regulations of the Ministry of Transport. As Mr. S. Tremlow himself remarked : "This has come on the railways, and is bound to on the roads."
While referring to Foden products, we may mention that several important improvements have recently been incorporated in the design of the 6-tonner. This now has Hoffmann roller bearings for the crankshaft, in addition to bearings' of this type on the eccentrics. The tubes are now welded in the firebox. Only a thin weld is required, but this makes maintenance far easier, for it obviates any danger of leakage at this point.
The rear brakes are now 4 ins, wide, with internal-expanding shoes in the rear-wheel drums. There is an improved type of hand brake on the main axle and another band brake on the compensating centre. Both the latter brakes are operated by a single pedal. The brakes in the rear wheels are also pedaloperated, and the driver, by placing his foot midway between the two pedals, can operate all the brakes simultaneously.