Marelli Vacuum Servo

mARELLI MAGNETOS (England), Ltd., are marketing an interesting servo brake mechanism which may be fitted to any car. Power is derived in the usual way from the reduced pressure in the induction pipe, but the suction is made to contract a rubber bellows instead of moving a piston in a cylinder. The bellows, besides needing no lubrication, is Said to be unaffected by frost Or grit.

The simplest .application of the servo is where one end of the bellows is secured to the chassis and a rod conveys the pull from the other end to the existing braking system, which is otherwise unmodified. An alternate and more elaborate scheme is to employ two of the bellows units, one on each side of the chassis. The front and rear brake on each side are connected to the two ends of their respective units, and the suction for each is supplied from a regulating valve placed behind the brake pedal. Depression of the pedal puts the engine suction in communication with the two units through branch pipes, and since the whole system will be under the same degree of vacuum, the braking effort should be equally distributed between the four wheels. The original linkage between pedal and brakes remains unaltered, so that it still comes into action if the Servo fails.

Anti-Glare Glasses. to

ONE. of the greatest dangers to which anyone is exposed who travels at high speed, whether by air, land or sea, is that of injury to the eyes through the breaking of goggles which one must necessarily wear.

The ophthalmic hospitals of London report a growing total of serious injuries to the eyes through breakage of glass lenses and goggles, and, whilst everyone for Some years has been aware that goggles can be made of timplinterable glass, they are probably not aware that modern developments have enabled these unsplinterable lenses to be supplied in a good goggle at a very reasonable price.

Dollond & Aitchison Ltd. of 28, Old Bond Street, are IICYW selling, in large quantities, a goggle with unsplinterable lenses at 15s. ; and since one can now buy a high class instrument at so low a price, it should be a crime for anyone to wear the old form lens or goggle. These unsplinterable lenses can now be worked with the sight of the wearer at a very small extra cost, and therefore

anyone with defective eyesight need no longer wear a goggle over his spectacles, but can get the full advantage of perfect vision and safety in the one goggle.

This firm also handles Crookes glasses, a sample pair of which we have recently tried, and found most effective in combating the glare, both of the sun or headlights. A feature of these glasses is that the lens is of light grey tint, so that colours are not altered to the wearer, as is usual with tinted glasses.

Checking Brake Efficiency:

TAPLEY Co., of Totton, South

ampton have added a new instrument to their range of useful performance indicators. This is a little device designed for the purpose of checking the efficiency of the brakes of a car. It comprises a metal casing with a rectangular dial on which are three graduations. The internal mechanism consists of three pivoted inclined tubes, width carry balls and their movement is transmitted to tablets inseribed ” Pair,” ” Good” and ” These tablets appear on the dial according to the rapidity of deceleration of the car, and they denote respectively 20 per cent., 30 per cent., and 50 per cent., braking efficiency, equivalent to a stopping

power in feet from 20 m.p.h. of 67, 45 and 27. The indicator is very carefully calibrated and checked in manufacture, and it can be relied upon to show accurately just how good or how bad are the brakes of the car to which it is fitted. Its dimensions are quite small, its width being only 21 ins., and finished in Chromium plate, with matt silver finish dial it is of particularly neat appearance. Its price is 18$.. 6d.

A Compass For Cars.

HENRY HUGHES & SON, Ltd., of Barkingside, Essex, the well known nautical and aircraft instrument manufacturers, have recently introduced a small compass for use on ears.

Of mat, compact design, it is intended for attachment to the windscreen, and a rubber shock-absorbing buffer is incorporated hi the mounting. The construction is based on the same principles as those of the ” Husun ” motor boat and aeroplane compasses, and in practice it functions very well under the arduous conditions imposed by road work. Its price is .43.

ForInner Tubes.

ANI W, patented substance known as ” KarboSite,” has recently been placed on the market which Claims to prevent deflation of tyres when Punctured by .small sharp objects, such as a nail or sharp stone. This compound is injected under pressure through the tyre valve and owing to its special composition, unlike many other puncture preventatives, it does not adhere to metal or rubber. Karbosite is in the form of a paste and contains inert asbestos fibres which tend to till up any small holes in the tube. Besides acting as an effective seal for the tube, it is also claimed by the mannfacturers that it definitely preserves the rubber, yet at the same time it has no adverse effect on the vulcanisation. The cost of treating the tubes with this substance varies, according to the size of the tyre, but the filling of a 27 x 4.40 in. tube is 7s. The name and address of the Makers is Karbosite. 2-4, Harehills Road, Leeds.

‘Super Suspension Spring Attachment.

” MOTOR SPORT” staff car has recently been fitted witn a set of ‘ Super Suspension spring attachments. This device comprises a -number of steel plates which house a series of hardened steel balls, in a similar way to that found in the centre portion of an ordinary thrust race. These plates (four of which are used for each spring in the case of a semi-elliptic suspension :system) are fitted between, and at the end of the first and second, and second and third leaves, and their effect is to allow the latter to slide one on the other with a greater freedom of movement. The result is a considerable increase in their periodicity and a more lively action.

Under test, the improvement in the riding comfort was most marked, while the steering appeared to be lighter than previously. The manufacturers, Super Suspension Ltd., of 20-26 Lonsdale Road, London, N.W.6, state that their attachment also tends to eliminate wheel bounce, and reduces the risk of skidding, and our experience after making various adjustments to the shock absorbers, indicates that these claims are by no means unjustified.

It is of interest to note that a free trial may be had of Super SuspenSion over U period of 14 days.

The cost of the attachment (a set of 16 races) is :— small cars £1 : 5 :0; light cars £3: 3 : 0; medium cars £4 : 4 : 0; and heavy cars £S: 5:O.