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AN INTERESTING VALVE GEAR.

5th August 1924, Page 30
5th August 1924
Page 30
Page 30, 5th August 1924 — AN INTERESTING VALVE GEAR.
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A fUsume of Recently Published Specifications,

THE objects of the invention which is, described in specification No. 217,835, by D. F. _Asbury, are most comprehensive. The patent relates to valveoperating gears, especially to those of the rocker-arm type and it is claimed that the adoption Of the idea which underlies .the invention will eliminate noise, friction, the need for lubrication and the necessity for even occasional adjustment of the relation between the various moving parts of the gear. The principal component of the valve gear and the one which enables these desirable objects to be achieved is' a toggle, which, it is claimed, is anti-frictional in its operation.

This toggle is, in effect, two links of an ordinary chain, of which one rests

on the upper surface of the rocker arm in a convenient notch. This serves as a fulcrum. The other is hooked on to a, bracket mounted on the • top of .the cylinder head. The working surfaces in all cases are convex upon flat, so as to diminish the frictional resistance to movement. A spring bears on to the side of the toggle at its joint, and tends to pull its ends together, thus exerting a force which is always pressing the rocker arm downwards on to the tops of both the tappets and valve spindles, thus ensuring constant contact and removing the necessity for taking up any wear which may take place.

Several variations in the arrangement of the parts are illustrated and described in the patent specification, but they are chiefly concerned with the arrangement of the spring which maintains the tension in the toggle, • and in no way do they vary the principle of the invention.

Other Patents of Interest.

TH.ERE are two features of interest about the tipping gear which is described in specification No. 217,867, by L. Mousset. The transmission gear has a good point which is worth noting, and the lifting mechanism embodies another of merit, The tipping gear is of the type in which a winch, hauling over a jib crane, lifts a strut which is attached to the underside of the body. An advantage of this type of tipping gear is that with a comparatively short jib to the crane, and an equally short strut beneath the body, a considerable degree of lift' can he effected. This means that the 'gear is not cumberiome B48

'even for a steep tipping angle. In the -present -construction, however, the advantage already noted is increased by hinging the strut and mounting a wheel at its lower end. This runs upon rails provided on the chassis, and so arranged that, as the body lowers to its normal position, the strut folds itself up underneath it to lie snugly between the longitudinal members of the frame of the body.

Power for tipping is derived from the gearbox of the chassis, and passes through a double-reduction gear, of which the first is a pair of bevels and the second a worm and wheel. The winch is mounted on the shaft, which is driven by the worm wheel. Actually, there are two pairs of bevels, consisting of two crown wheels on the vertical spindle, and two pinions, which are loose on the shaft from the gearbox, and designed to be coupled to it, one or other of them—but only one at a time—by a sliding dog clutch, which is actually splined to that shaft. As the crown wheel which is used for the lifting of the tip gear is larger than that which is used when the body is being lowered, it follows that the gear affords a quickreturn motion.

CENTRIFUGAL •force is one of the troubles which assail magneto contact-breakers when the engines to which they are fitted begin to " rev." The Soc. des Moteurs Salmson have been erdeavouring to discover a way to circumvent this particular trouble, and claim to have found a satisfactory means, which is described by them in specification No. 201,542. The rocker arm of this contact-breaker is strongly made of sheet steel, stamped to U-section and . reinforced with a, lining of fibrous material. The arm itself is pivoted close to its cease, one end being equipped with the platinum-tipped screw, and the other having a projecting fibrous pad which engages the breaker cam. Centrifugal force, therefore, has Only the effect of producing a bending stress in the arm, which stress it is specially designed to be able satisfactorily to resist.

AN improved electrical method of con

' trolling the fuel supplies to a Diesel engine, and applicable also t6 other uses similar in their stature, is described in specification No. 210,034, by L. Renault. Previous constructions of electrical apparatus for this purpose have embodied an electro magnet and return springs, but delay occurs in the -operation of this type of gear, owing to selfinduction effects in the electrical windings. In the present design, instead of relying merely on the'. make-and-break of the current in the windings, Provision is made for the continuous supply of current to the electro magnet, and for the release of the magnetism by means of a contra current which is supplied to a conductor of practically negligible selfinductive capacity.

THE provision of supplementary castor wheels under the front end of a chassis to faciiitate manceuvring confined spaces is not ' new. The

mechanislIn of that kind, which is described in specification No. 208,559, by A. Colleye, has the novel feature that it is s3lf-elevating. According to the inventor, such turning gears have hitherto been fitted with jacks, and have corn. prised one or more wheels, each carried by a vertical screw spindle whereby the ordinary steering wheels would be lifted from the ground when the extra wheels are lowered. Alternatively, the power of the engine is used to elevate the chassis upon this supplementary support. In the present invention means are provided whereby the lifting is more easily and effectively accomplished.

GYROSCOPIC and inertia effects are

combined in the change-speei and differential gear which is cleseriled in speci5cation No. 204,062, by B. Mauwilier. In its simplest form the gear consists of a casing containing a crossshaft, on which are keyed a bevel, pinion and a flywheel, as well as a crown wheel which is keyed to the driven shaft. The easing itself is bolted to the engine flywheel, and is driven thereby. The engine may tick over slowly, rotating the cross-shaft and the easing, but without moving the vehicle. Acceleration of the engine will start the vehicle in motion, and, as it accelerates, the speed of the flywheels will diminish until a direct drive obtains. Upon additional resistance being encountered, the crossshaf'; with its flywheel will recommence to re• volve and modify the gear ratio to suit the conditions.

SIMPLICITY may be said to be the

• keynote of the change-speed gear which is described in specification 'No. 217,690, by G. H. Hopkinson. The driving shaft is out of line ° with the driven one. The latter carries, keyed upon it, a wheel, on which are cut two sets of teeth, one internal and the other extesnal. The internal set engages a pinion freely mounted on the driving shaft; the external one gears with the intrrnal teeth of another, also freely

mounted, on the exterior bf a sliding sleeve, which is splined to the driving shaft, and which is designed to engage _ either the pinion or the • internally toothed wheel on the driving shaft. By that alternative engagement two ratios of gear are obtained, In another arrangement four speeds.are provided-by similar pearls.

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