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A Simple Multi-speed Gearbox

29th March 1935, Page 122
29th March 1935
Page 122
Page 122, 29th March 1935 — A Simple Multi-speed Gearbox
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Which of the following most accurately describes the problem?

FROM 0, D. North, P. G. Hugh, and Scammell Lorries, Ltd., 52-54, High Holborn, London, W.C.1, comes an interesting patent,. No. 423,952, showing a gearbox giving, six forward speeds and -a reverse, " yet requiring only fonr pairs of gearwheels. , The design uses two parallel shafts, the upper being engine-driven, whilst the lower forms the output shaft. Each shaft is divided into two portions, which may be coupled by means of dog clutches.

In the drawing, which is purely diagrammatic, the fixed gears are shown as part of the shafts, whilst free gears are drawn spaced away from the shafts. Dog-clutches are represented by shaded rectangles. The following gives the gears used in each ratio, it being understood that the requisite clutching operations are carried out :—First speed, 1-A, 13-2, 4-D; second speed, 1-A, C-3, 4-D--;third speed-, 4-D ; fourth speed, 1-A; fifth speed (1 to 1), 3-C ; sixth speed (increase), 2-13. Reverse is obtained by an idler gear.

Automatic Brake Adustment.

AKNOWN method of automatically adjusting brakes consists of a ratchet-and-pawl mechanism operating on the return stroke, which gathers up any excess slack and provides a new

zero position. With this method, however, should the • brake pedal or lever be allowed to fly hack suddenly, the pawl may gather one or more teeth, giving a zero position with the brakes partly on. To avoid this• defect is the object of patent No. 4'24,178, by Societe Anonyme Adolphe Saurer, of Arbon, Switzerland.

In the accompanying drawing, the operating piston swings the toothed segment (3), which operates the brake arm via the pawl (10). On the brake spindle is a ratchet wheel (8), which moves with the arm, after a certain amount of lost motion, indicated at 9. Should the movement exceed a p:.determined maximum,maximum, one of the pawls (6 and 7) gathers a tooth, which on the return causes the pawl (10) also to gain a tooth, owing to the limitation of the gap. (9).

So much is known practice, but this invention goes farther, in -providing a seeon-cl toothed segment (5) of opposite hand to the main one, and hav

JA6 ing its own paw! (4): At rest, and for the first few degrees of movement, this pawl is held out of action by a freely mounted plate (1) acting on abutments (2), but after these have disengaged, the opposing pawls lock the two segments together, so that a fly-back of the brake control cannot effect relative motion.

Damping Torsional Oscillations in Oil Engines.

TE high compression used in oil en often gives rise to considerable torque fluctuations, which may be sufficient to set up undesirable tor.. sional oscillations, unless some method of damping be used. Such a device is shown in patent No. 423,948, by J. A. Daniell, of Hardy, Spicer and Co., Ltd., Witton, Birmingham. The scheme calls for a massive ring frictionally mounted on the flywheel rim ; if necessary to act as part thereof. The drawing shows one form of construction; in this case a dual rim is used. A V-groove is formed on the flywheel, carrying friction material, and the two rims are forced into contact therewith by interior coil-springs. To prevent damage to the springs, the rims are sliclably dowelled together.

The Prevention of Spring Twisting.

ASUSPENSION system in which provision is made for movements caused. by differing lifts being applied to wheels on the same axle is shown in patent No. 424,167, by Societe Anonynie Adolphe Saurer, of Arbon, Switzeiland, • Referring to the drawing, the spring is secured to a bridgeshaped, platform., (1) which stands clear of the central axle tube.The load" is taken on two tubular members (3) which form part of the axle-casing end. The spring platform eyes (2) are spherically bushed, and can at the same time move slightly endwise, iso that movement " in two planes is possible without deformation of the springs. The two tubular members (3) are also used to house the brake-cam spindle and retaining pin. A further drawing shows a similar scheme, in which rubber blocks are substituted for the spherical bushes.

Hydraulic Brake Improvements.

AN invention designed to prevent in.leakage from the brake cylinders of a hydraulic system is shown in patent No. 423,954 by j. W. White, 18965, Muirland Avenue, Detroit, U.S.A. The cylinder illustrated is of the type which forms a self-extending unit, and can be used with several types of brake mechanism, The cylinder is made in halves, each Of which is screwed into a central boss (3) contamingthe supply "pipes. Each half contains its own piston (4) and : a riibber cup-washer (2) gripped by its flange. "

In operation, fluid is pumped into the interior of the cup-Washers, causing them to extend and move the pistons, with no possibility of leakage. In order to keep the quantity of fluid in the cylinder at a minimum, a hollow steel dibpla.cer (1) almost fills the space between the cup-washers.

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Locations: Birmingham, Arbon, Detroit, London

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