NEWNES PRACTICAL MECHANICS
LAST year I described in a series of articles the construction of a Midget Three-Wheeled Car powered by an air-cooled single cylinder motorcycle engine of a capacity up to 500 c.c. Very many cars have been built from those designs, blue prints for which are still available at 10s. 6d. per set. They have all performed very satisfactorily on the road, and the constructors have written me enthusiastic letters paying tribute to the simplicity of the construction and the reliability of the little vehicle on the road. It was designed to give the performance of a motorcycle but the weather protection of a car, and this object it fulfilled admirably. I have published photographs of some of the cars built from my drawings, and readers will be able to gauge from those as well as from the photographs of my own car the practicability of the design.
It was, however, a monocar, and many readers wrote asking whether they could widen the body to accommodate a passenger. I advised them against this, since the chassis members and other parts would have needed considerable modification to have made the car strong and roadworthy.
Ever since the conclusion of the series of articles I have received a steady flow of correspondence asking me to prepare a design on somewhat similar lines suitable as a twoseater. I have given a great amount of thought to the matter, and decided that such a design would not be satisfactory as a three-wheeler, and accordingly I set about preparing a design for a four-wheeler but adopting a somewhat similar form of constructions as for the three wheeler. Therefore, it will not be necessary for me to go over that ground again, and I would refer readers desirous of building the present design to those articles which appeared in our issues dated March to
August, 1936, back numbers of which are still available.
The Present car will need a more powerful engine, and I suggest one of at least 500 c.c, but preferably 750 c.c. Either a single cylinder or a twin cylinder will do. A motorcycle gearbox of the 3-speed type and suitable for the engine should also be obtained. The top gear ratio should be 7-1, to prevent the engine from overheating, and as with the three-wheeler, an air chute underneath the seats should direct a blast of air direct on to the cylinder.
Additionally, wheels fitted with at least 3-in. tyres should be used. Motorcycle sidecar wheels with internal expanding brake hubs should be employed, and it will be a comparatively simple matter to couple the brake operating mechanism so that all wheels are braked simultaneously. The body is constructed as before from three-ply, but the framing allows of variation in body form to please individual ideas. In many ways this four-wheeler is simpler to build than the three-wheeler, since it dispenses with the rocking bar type of rear suspension, and makes use of standard 1/4-elliptic springs. These may be picked up quite cheaply from car breakers and by a suitable modification of the eye end they can be made to accommodate the live axle. I have not deemed it necessary owing to the comparatively narrow wheel track to employ differential gear. It will be remembered that some of the light cars of a few years ago, notably the Bleriot Whippet, did not employ a differential, although the wheel track was much wider than in the present case.
It will be seen that I have arranged the seating accommodation further back, Which has necessitated a corresponding increase in the wheelbase. The same system of direct steering is employed; this has been found after long experiment quite satisfactory on the three-wheeler. It should be even more so on a four-wheeler. The front suspension is the same, and consists of coil springs with snubber springs underneath.