THE REFINEMENT OF CHASSIS DETAILS.
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A Résumé of Recently Published Patent Specifications.
NO FEWER than five of the inventions with which we have to deal this week are registered by F. H. Royce, of Rolls-Royce, Ltd. Two relate to carburetter design, two to overhead-valve gear, and one to a form of resilient drive for camshafts.
The first carburetter patent, No. 222,526, has as its object the overcoming of the tendency of the liquid fuel to become deposited on the walls of the induction pipe of a multi-cylinder engine. The construction which is described in this specification embodies a special type of diffuser jet, the head of which is located in a small ehoke tube. This delivers a rich mixture of petrol and air into an exhaustheated chamber, more air being added subsequently, as the mixture travels on its way to the throttle valve. Provision is also made (in the shape of a suctionoperated piston) for the automatic control of the fuel supply to the jet, as well as the proportion of air, according to the degree of vacuum in the induction passages. It is claimed that the automatic device and its essential controlling passages are so proportioned that at all speeds and throttle openings within the range of the instrument the desired ratio of petrol and air will be attained.
The novelty of this invention appears to lie in the combination of several .known and previously tried devices, each of which, in itself, is familiar to motor vehicle users. It is not new, for example, to supplya rich mixture from a jet the constriction of which is controlled by a suction-actuated valve, along with a small quantity of additional air drawn through a choke tube, and to pass the resultant mixture through a heating apparatus, subsequently mixing the heated gas with the requisite quantity of cold air. It is not novel either to make use of a variable automatic diffuser jet with the constriction controlled, as in this case, by a tapering needle valve which is opened or closed automatically in accordance with the suction in the induction piping. The invention lies in the combination of these two . devices in the manner which is described in the specification. Althotigh apparently complicated, the combination is carried out in a comparatively simple manner.
145 MORE intimate and thorough mixture of the fuel and air as well as more perfect and regular carburation at all engine speeds are the advantages claimed for the carburetter design which is described in specification No. 222,901. Like the former patent, this has some familiar features, such, for example, as the mushroom-shaped jet, with the orifices all round the edge, opening into a choke tube at or near its narrowest part.
In this particular carburetter the choke tube, which is of specially designed crosssection, is lifted and lowered by a piston which is controlled by the suction in the induction pipe. The same medium also controls the flow of petrol, utilizing the tapering needle, as in the other construction described above. Means are provided for the manual operation of the jet, which can be lifted or lowered in the choke tube, thus establishing a control over the general strength of the mixture throughout the full range of operation of the automatic device.
AN invention to improve the means Of
adjusting the clearances between the ends of the push-rods and the rockers, or between the latter and the ends of the valve stems, is described, again by F. H. Royce, in specification No. 222,521. The inventor's object is to avoid the alternative disadvantages of increased weight of moving parts (brought about by the use of screwed or similar adjustments), or difficulty in securing. the adjustment, after it has been made, without altering it to some slight extent. According to the construction described,, the rocker shaft, which does not rotate, is mounted in a number of standards or brackets on the top of the cylinder head. it is secured in the centre one by being screwed and clamped into it ; the boss of the supporting bracket is split and the halves closed by a bolt. Each rocker is mounted on an eccentric bush, and each bush is independently adjustable. After the adjustment is made, nuts on the ends of the rocker shaft are tightened, squeezing the eccentric bushes together, so that they cannot move. This does not cause any alteration of the adjustment of those bushes, so that the clearance is unaffected by the final securing of the adjustment.
IN a subsequent specification—No. 222,790—the same inventor provides means, in the form of small worm spindles engaging worm teeth on flanges on the eccentric bushes, whereby the adjustment of the clearances may be carried out with ease to. very fine limits of accuracy.
THE resilient driving gear for a cam shaft which is the subject of the fifth Rolls-Royce specification embodies a plate or disc mounted on the boss of the crankshaft timing pinion, and clamped to a similar disc rigidly Mounted on the crankshaft by a spring-loaded pressure plate, which is also mounted so that it rotates with the shaft. A positive but resilient drive is also provided by helical springs, held between lugs on the boss of the timing pinion, and others on the disc carried by the shaft. The friction drive arrangement provides against the possibility of endwise movement, particularly in cases where the timing gears may be of the helical type, whilst the flexible spring drive eliminates the chance of slippage of the friction drive.
Other Patents of Interest.
LOCKING gear designed to prevent the gears of a change-speed gear employing helical-toothed wheels from slipping out of mesh endwise is described in specification No. 2=,734 by Soc. Anon. des Automobiles Unic. A slotted bracket, with a dependent catch or stop, engages the selector lever in such a way that, after a gear has been engaged, lateral movement of the change-speed lever causes this catch to engage a corresponding notch or projection on the selector fork, prevent ing its movement until the selector rod is again moved to disengage the catch so that the gears can be changed.
PETROL ELECTRO MAGNETIC
transmission of the type in which the engine transmits its power to a driven shaft through an electro-magnetic clutch so constructed that, when slipping of the clutch takes place, current is -generated and is led to an electric motor on the driven shaft, whereby the torque on the latter is increased, the current generated being also led to electro motors with which other axles of the vehicle are provided, is described in specification No. 222,578. • In the particular construction and arrangement of parts with which the specification is concerned, a horizontal engine of the opposed-cylinder type is employed, thus considerably reducing the over-all height of the complete power unit and making it possible to apply it to existing vehicles. The patentees are Hobdell,
Way and Co., Ltd.. "
CERTAIN modifications in the Lavand infinitely variable change-speed gear, which has already had reference in these columns, are described in spedfication No. 220,640 by D. S. de Lavaud.