New Location for the Power Unit
Page 34
If you've noticed an error in this article please click here to report it so we can fix it.
A Resume' of Patent Specifications that Have Recently Been Published
UNORTHODOX design is often a feature of vehicles produced by the Tatra concern, of Prague, Czechoslovakia, and its latest effort, dealt with in patent No. 476,101, is certainly a novelty. 'The scheme is intended for use -with radial-cylindered air-cooled engines, which are, themselves, a novelty so far as road vehicles are concerned.
The Accompanying drawing shows how the engine is housed in an overhung compartment on one side of the vehicle, symmetrical appearance being maintained by mounting the spare wheel in a similar housing on the opposite side. The transmission shafts are clearly shown, but no mention is made of the clutch and the gearbox ; these, presumably, would be incorporated in the rear-axle assembly. The drawing also suggests that swinging half-axles are employed, suspension being by leaf springs.
The patent is extended to cover the application of the design to railcars, in which case the engine would be housed just insidethe body lines.
Two-stroke Engine with Self-contained Pump.
PROBLEMS of uncertain scavenging are claimed to be overcome by a design of two-stroke engine shown in patent No. 476,097, by W Grab, 15 Konradstrasse, Freidburg im Baden, Germany. The engine described is made up in units of two cylinders sharing a charging pump. Referring to the drawing, the two power pistons (5 and 9) work in cylinders equipped with exhaust ports (4) at stroke bottom, and are set 180 degrees apart on the crankshaft. Between the power cylinders is a pumping unit comprising a piston (1) surrounded by a sliding sleeve valve (8). The piston is reciprocated at twice engine speed by means of a secondary geared-up crankshaft (6) and draws in mixture from a port (2). The mixture is compressed and delivered to each cylinder in turn under control of the sleeve valve, which is
moved by an eccentric (7) on the crankshaft.
In operation, the exhaust gases pass Out of ports 4, assisted by a charge of compressed mixture from ports 3. The charging is continued after the exhaust ports have been closed by the rising piston, so that a degree of supercharge can be obtained by timing the sleeve valve accordingly ; this is said to neutralize the loss of stroke due to the length of the exhaust ports.
Internal Cooling for Valves.
PATEN. T No. 476,089 describes an unconventional scheme for cooling valves, and shows a valve operated by compressed air ; although the latter forms no part of the patent, it is, nevertheless, of interest. The patentee is Motoraktieselskapet a.v. 1935. Kongensgate 6, Oslo, Norway. In the drawing the valve itself is hollow. and it contains a twisted strip (5) which divides the bore into two passages. For cooling purposes compressed air enters via the port (3) and passes down one side of the helical strip, around the head, and returns to exhaust from a vent (1).
The valve is operated in a closing direction by air pressure from port 4 acting upon a large-diameter piston (2) carried on the stem, but no details are given of the method by which the valve is to be opened, although cam and tappet operation may he inferred from the remark that the air pressure is intended to replace the usual spring.
Producing an Anti-friction Surface.
AMETHOD of treating cylinders, pistons, valve stems and other wearing parts in order to produce an anti-friction surface forms the subject of patent No. 474,252 from J. 111cLintock, 14, Finlay Drive, Dennistoun, Glasgow. The process consists of the application of a solution containing graphite, gum and water. This is to be applied to the part to be treated, after which it is baked for 24 hours at a temperature of 300 degrees Fahrenheit or more. The resultant finish is claimed to possess the remarkable property of needing no lubricant whatever.
Whilst so simple a means for gaining this valuable end seems likely to be received with scepticism, the scheme may conceivably be practicable.
Alternative Four or Six-wheeled Vehicle.
THE central tubular chassis is much favoured by modern Continental designers, and patent No. 476,091, from
Tatra-Werke Automohil-und-Waggonban A.G., of Czechoslovakia, discloses a scheme by which such a vehicle can rapidly be converted from four-wheel to six-wheel driVe. The method is specifically applicable to vehicles which have not been specially designed with a view to conversion.
In the accompanying drawing, which is purely diagrammatic, the original rear-axle assembly (1) is parted from the engine unit (4), and an extra axle unit (3) _is then inserted in the intervening space, the 'original axle being rebolted to the rear of the new unit with a suitable distance piece for length adjustment. The additional axle is a counterpart of the other, except for the provision of a long drive shaft (2) and a double differential gear. The last named is to balance the drive between the two assemblies, each of which carries its own local differential of the usual type.