DEMONSTRATING THE HOLLE CHASSIS,
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A Remarkable Series of Tests on a Vehicle with Four-wheel Drive and Four-wheel Steering.
MHE CAPABILITIES of the in
genious chassis, which wee fully described in The Commercial Motor dated October 16th, were convincingly demonstrated before Col. Wilfrid Ashley, of the War Office, and a large party of Pressmen recently. A very suitable site was chosen for these tests, this being the narrow valley situated about, half-way up the well-known Box Hill (near Dorking, Surrey). It will, perhaps, be as well to recapitulate a few details of the design before proceeding with a description of the tests which were carried out.
Incidentally, although the vehicle which .has been oonstructed is more or fees of the pleasure car type, it must be understood that the design throughout is particularly applicable to heavy lorries working under arduous conditions of the Colonial Variety. It is intended to proceed with the construction of a three-tomer on similar lines, and designs have actually been planned for a multiwheel chassis embodying much the same principles.
It will he recalled that a power unit and gearbox of orthodox type are used, the latter unit being placed near the centre of the chassis and incorporating what is known as a distributor box. This box contains a differential and two bevels, meshing with which are four pinions for transmitting the drive through Shafts to each of the road wheels. This design, results in a balanced differential action between the near pair and the off pair of wheels, which is all that is needed for cornering. In addition, by mounting a large transmission brake at the forward end of the gearbox, the virtual effect of balanced four-wheel braking is obtained in a simple manner.
Each of the wheels is carried by jointed links, there being no axles, and is free to move vertically a distance of about 12 ins, under the control of damped cantilever springs, which are adjustable in accordance with the speed and the load. Owing to the independent, action of the wheels, very rough ground can be covered without the transmission of undue shock to the frame.
Another novel feature is the way in which the wheels are coupled together for steering purposes; the gear is so arranged that the rear wheels track correctly with those at the front, so that there is no cutting-in tendency on corners. This is particularly valuable feature for a lengthy chassis, it beinv unnecessary to awing out into the -road when a snarp turn has to be negotiated.
Many designers would have been content with these features, but Mr. Rolle, who invented the chassis, has gone a step farther by providing an extremely ingenious control, by means of which the coupling-up of the wheels can be altered when desired. Shifting a lever results in the lock on the rear wheels
becoming the same as that on the faint, the net effect being that. the chassis can be driven bodily sideways . when required. The crabwise movement so obtained would be particularly useful for moving out of a long line of vehicles.
The tests undertakers last week demon'anted the capabilities of the design in a very thorough fashion. The chassis was driven up, down and around the slippery turf on gradients which must have exceeded 1 in 4; it. was always under the complete control of the driver and remarkably acute turns were made on the grassy slopes without any observable skidding. The writer was given a short run in the car under these conditions and can vouch for the fact that, even when traversing extreniely rough surfaces and ruts, the wheels move up and down without transmitting any unpleasant shocks or vibration to the frame.
A demorkstration was then given, of the crabwise movement, the car running at speed in a direction which was roughly at 45 degrees to the centre Tine of the frame. After this, an adjournment was made to the Burford Bridge Hotel, in-order to take advantage of a very slippery. stretch of tar macadam rood, on which the non-skidding properties of the desien were amply demonstrated.
Violent braking was indulged in, both on the straight. and when cornering, without either locking the wheels or causing the least skidding tendency. Furthermore, a complete turn was made at a speed approaching 20 m.p.h. between kerbs which could not have been more than 35 ft. apart. Although it may sound incredible, no outward skid occurred, a fact that was verified by the writer, who examined the wheel tracks left on the surface without being able to detect any sign of slipping.
The design is truly . one which posseaaes many extremely interesting possibilities, and we were particularly struck by the non-skiddingproperties, which should be very valuable for passenger services. Needless to say, an extremely small turning circle can be obtained when the wheels are all actuated together in this way.
Further'developments with heavier types of chassis will be watched with great interest, particularly those relating to the multi-wheeler. N'Ve understand that the interests of the inventor are in the hands of Mr. B. Hadyn White, 30, Norfolk Street, Strand, London, W,C.2, and that patents covering the main features have been obtained in all the
important .countries. .
In addition to having. interested the War Office with this design, we underStand that -those concerned with the . development of . the chassis have .conducted a special deniOnstration of its capabilities before the technical staff Of the-London General Omnibus Co. Some of the trials were carried out on the Company's testing track, and a stretch was specially prepared with slippery, substances to demonstrate the non-skidding pforiertieS: of the chassis. Mr: White informs us that, the performance'wag a highly creditable one, a fact which we can readily believe' after seeing the trials recorded in this article.