A Novel Valve-guide Assembly
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A Résumé of Recently Published Patent Specifications
DATENT No. 406,815, by Oliver D. 1 North, Percy G. Hugh, and Scamme! Lorries, Ltd., 52-54, High Holborn, London, W.C.1, describes an interesting method of assembling a valve and valve guide so that the valve may have an enlarged portion at the end of the stem and yet avoid the difficulties in" the production of the split valve guides. The mailed suggested is to assemble the guide upon the valve stem, the end of the stem then being enlarged by heating and "upsetting." The valve and guide are henceforth inseparable, 'and in this condition must be inserted in the engine. The drawing shows one method of fixing the guide in position, a taper portion seating into a corresponding bore in the engine casting. A groove is turned at the bottom of the taper into which a powerful spring ring is pressed. An advantage of this method is that the valve may be ground to size, using its own guide as a bearing. This procedure ensures absolute concentricity of the head with the stem.
Overcoming Excessive Fuel Injection. A CCORDING to patent No. 406,956, Pt by Robert Bosch A.G., Stuttgart, Germany, recent research has shown that the pintle type of spring-loaded nozzle suffers from the defect that the rate of fuel injection is excessive at the commencement of injection, which gives rise to heavy running, especially at low engine speeds. This is due, it is believed, to the fact that at the moment of opening, the compressed fuel acts upon the additional area offered by the valve seating and unduly accelerates the needle. To overcome this trouble, it is proposed to use a much stiffer spring than hitherto, the dimensions suggested being 4-mm. diameter for the spring wire and 16-mm. outside diameter for the 4i-turn spring. In addition, the tip of the needle is made to fit its bore with a slight clearance, so that at the early part of its movement the fuel is considerably throttled. As the needle rises, however, a smaller conical portion is uncovered,„ thus hastening the flow of fuel. Detachable Rim Refinements. TROM Michelin et Cie, Clermcnt Ferrand, France, comes patent No. 406,904, describing improvements in the form of detachable rims. This patent refers to the type of rim in which a retaining split-ring is locked in position by the pressure of the tyre. The drawing shows the detachable rim proper (1), which is forced outwards by the tyre pressure against the split-ring (2). The angle of engagement between the Tu'IF rim and the ring is and its groove, so greater than that between the ring ATsure tends to force that the tyre pres ,406.9.56 the split-ring deeper into its groove. A further feature is the absence of contact between the rim (1) and the base (3).
A Compact Epicyclic Gear.
ACOMPACT epicyclic-gear layout giving four speeds and a reverse is shown in patent No, 406,883, by Coom Kittilsen, Lille Traag, near Porsgrund, Norway. The usual type
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of epicyclic gear has brake or similar arrangements to operate the various ratios, but this inventor prefers to use dog clutches for the purpose. Compactness is obtained by the use of bevels for the sun and planet gears. Referring to the drawing,_ there are four control members, two rotating dogs (2 and 4) and two stationary stop-dogs (3 and 3). A straight-through drive is obtained by sliding dogs 2 and 4 into a central splined sleeve, whilst other ratios are selected by the inter engagement of the necessary epicyclic members. For example, reverse is obtained by moving dogs 4 and 3 to the left, and dog 2 and stop-dog 1 to the right.
A Novel Air Filter.
PATENT No. 406,396, by Douglas 1 Motors (1932), Ltd., and C. G. Pullin, both of Kingswood, Bristol, deals with a type of air filter in which the filtering medium is a film of oil. Referring to the drawing, the air intake ,(2) leads into a chamber in which is disposed a number of discs (3)., Alternate discs reach to the outer case and the inner tube, so that a tortuous passage is provided for the air, the flow Oi which is indicated by
arrows. .
. A tube(1) communicates. with the crankcase, whence it brings a supply The Priming of Injection Systems. IN order that an injection pump shall 1 operate satisfactorily, it is necessary that the whole system be filled with fuel. If this be not the case, the starter, whether human or mechanical, has to turn the engine until the injection pump has completely filled the piping and nozzles. Realizing that it is not necessary to turn the whole engine to work the pump, the Societe Generale des Carburateurs Zenith, 10, Rue Peti tot, Geneva, Switzerland, has patented (No. 405,188). a simple form of injection-pump coupling which can be disconnected for the purpose of hand rotation to prime the system. The method employed is to use a sliding dog on the pump spindle, engaging with a corresponding one on the driving shaft; the important requirement being, of course, that they will not mesh except in one angular position. This is achieved by providing the teeth with some irregularity which must, find its complement on the other dog before it is possible for engagement of the coupling to take place.