Hydraulic Operation of Engine Valves
Page 62
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A Risumi of Patent Specifica. (ions That Have Recently Been Published
NOVEL proposals are made in patent No. 404,426, by A. J. and G. R. Thatcher, both of Atworth, Melkshara, Wiltshire, in respect -of the hydraulic operation of inlet and exhaust valves. The scheme suggested is to use's pair of cams (one for inlet and one for exhaust), and with these actuate a number of pistons arranged radially around them. The pistons are each connected by a tube to one of the engine valves, the motion being hydraulically transmitted.
The specification states that it may be of advantage to have an advanceor-retard control of the valve gear: this system would lend itself admirably to this purpose, the necessary adjustment being obtained by rotating the hydraulic timing case about its axis.
• It is further claimed that a reversing mechanism could easily be fitted, Improvements in the Form of Gear Dogs.
PATENT No. 404,567, from Ilaybach Motorenbau G.m.b.H., of Germany,
shows a form of dog-clutch tooth which will, it is claimed, permit of slight axial misalignment, bearing slack, or other inaccuracy, without tending to work out of engagement.
Referring to the drawing, which shows a few teeth in engagement, it will be seen that the actual area of contact is small, being that between the two dotted lines (1 and 2). The rest of the tooth is relieved in all directions, so that any relative error between the two members causes them to function slightly as a universal joint. The formation of the end faces of the dogs is to facilitate bringing them into mesh and has no direct hearing on the alignment.
Road-rail Transport.
THE transport of railway wagons by road is an interesting subject in these days of co-ordination, and patent No. 404,130, from Gothaer Waggon-. fabrik, A.G., Gotha, Germany, shows a method of solving some of the problems connected therewith,
According to the specification, the weight of railway wagons necessitates a massive vehicle to carry them, which in turn leads to difficulties in connection with excessive overall height. The remedy suggested is to use a road vehicle consisting, in its simplest form, of a number of wheeled trolleys, each with a pan or well to accommodate a wheel of the rail-wagon. These trolleys are coupled with track rods and links for steering purposes, and are to be towed by a tractor vehicle.
The specification is voluminous, containing eight pages, and 29 illustrations, describing various modifications, including a tipping gear.
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A N attempt to combine the wearresisting properties of iron or steel with the lightness and thermal conductivity of aluminium alloys is shown in patent No. 403,390, by W. A. Oubridge, Parklands, Park Road, Coventry.
The object of this invention is to avoid machining and assembly,. the two parts being cast together: An essential feature it that the gudgeon pin bosses shall be formed in both metals in order to help to key together the two portions. To allow for different rates of expansion, a crimped steel ring may be employed to exert a pressure between the upper aluminium section and the low steel part which forms the skirt. Improved Metering for Injection Pumps.
1 T is well known that mechanical devices, although identical in dimensions, may yet differ in their performance; particularly is this so with injection pumps, and patent No. 404,339, by Amal, Ltd., and W. Comery, both of Holford Works, Perry Barr, Birmingham, describes a modifieation designed to eliminate some of these differences.
According to the inventors, an injection pump which starts to compress the fuel immediately the piston has passed the inlet port is subject to slight leakage at• this point. This is due to the very small sealing area available, being practically an edge-to edge contact for a moment. To overcome this, it is proposed to use a non-return valve (4) which functions also as an additional piston. In operation, the main piston (3) rises, and after passing the inlet ports (2) carries a charge of fuel above it, at the same time raising the pistonvalve (4). The point to observe is that compression does not commence until valve 4 has uncovered port 1; by this time the lower piston is Well away from the inlet port (2), thus reducing the possibility of a slight back-leakage.
The travel of the valve (4) is limited by a stop which obviates the need for an excessively strong spring to be provided. behind it.
Gearbox Modifications.
AN unusual method of selecting and engaging gears is described by P. C. Campbell, 6, Park Hill Court, Beeches Road, London, S.W.17, in patent No. 404,365. The design calls for a tubular layshaft, containing the sliding operating member. The latter consists of a dog with teeth which project through slots in the tube and engage with corresponding teeth cut in the bores of the layshaft pinions. This method gives a neutral position between a.ny two speeds: it is reminiscent• of a type of change-speed gear used in the early days of motoring, and known as the " disappearing feathes.".
A further 'claim is based 011 an additional attachment, electrically operated, Which gives the driyer visual
• evidence on tine dashboard of what speed is engaged.