• AN INGENIOUS ALBION HYDRAULIC BRAKE.
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A Resume of Recently Published • Patent Specifications.
THOMAS BLACKWOOD MURRAY and the Albion Motor Car Co., Ltd., illustrate, in their specification No. 248,144, a very ingenious hydraulic brake. This arrangement, although at first sight it may not seem novel, embraces many new and useful features. In the first place, it acts
equally well no matter in which direc tion the vehicle may be inclined to run In many brakes of this class a reverse of the direction of the vehicle means a reversal of the flow from the gear pump and a consequent suction instead of pressure in the brake-actuating cylinder: In this case, however, the flow of the pump is unidirectional. Another and most important feature is that the driver can "feel" exactly how hard be is applying his brake, as the pressure exerted in the brake-actuating cylinder is in exact relation to the muscular effort exerted on the brake pedal. This appeals to us an essential feature of all hydraulic brakes.
A further essential feature with which this brake conforms is the fact that, should the hydraulic assistance fail through any cause, the driver has the usual power over his brakes by means of a direct connection from pedal lever to brake-operating cam.
As will be seen from the illustration, a gear pump, driven from seine part of the transmission, sets up a continuous flow of fluid which travels round a closed circuit (the casing of which is not shown). The lower pipe leads from a reservoir from which the pump sucks oil and delivers it to thc brake-operating cylinder, and when the brake is not in operation it is allowed to escape from the opening of the controlling valve and to return to the reservoir.
No movement of the brake-operating piston can take place so Tong as this valve is open, as the oil will flow freely from the aperture and return to the tank. When it Is necessary to apply the brake, a movement of the pedal lever tends to close the control valve, so diverting the flow of oil to the brakeoperating cylinder.
It is obvious that to dose this valve against the pressure of the oil will require some effort, which effort will be in exact relation to the pressure exerted on the brake-actuating piston. It will be seen that by this means the driver is able to "feel" exactly how hard he is applying his brake.
It will also .be seen that the brakeoperating piston is mounted directly on the ordinary brake rod, so that, should the hydraulic flow cease, the floating lever will entirely close the control valve, which will form a fulcrum and enable the usual application of the brake to be made by means of the ordinary brake rod.
The ball valves in the pump act alternatively as inlet and outlet, according to the direction in which the pump is revolving, so that a continuous flow passes through the upper pipe, no matter in which direction the vehicle may drive the pump.
A Ball-thrust Bearing.
THE Cornpag,nie d'Applications Alecan nines describe, in their specification No. 243,676, a form of thrust-ball bearing which, they claim, reduces the jamming effect due to centrifugal force set up by the balls when running at very high speeds.
The effect of centrifugal force in such bearings has been recognized by our makers, and thrust bearings are made in this country which overcome the difficulty by the use of what is known here as the double-purpose bearing. In the present invention the grooves are both made more nearly to encircle the balls than in the usual thrust bearing, which the inventors claim has the effect of supporting the thrust of the balls due to centrifugal force, and prevents the possibility of their jamming between the grooves. A further claim is made that the cage need not extend beyond the balls so as to confine them within certain limits, and thus counteract the effect of centrifugal force.
Front Springs Suitable for Front-wheel Brakes.
A FORM of quarter-elliptic spring is
shown by Wolseley Motors, Ltd., in specification No. 248,032. This is specially adapted to withstand the reaction of front-wheel brakes. The lowest leaf of the spring forms an eye to which the front axle is pivoted, whilst
the extra leaf shown above the rest Is jointed to a vertical extension rising from the front axle, thus forming a parallel-ruler construction. A One-way Brake or Clutch.
AN arrangement that is claimed to he available for use as a brake or for a clutch is described in specification No.
248,106, by Armstrong Siddeley Motors, Ltd.
The specification mentions the fact that this brake will act with greater effect in one direction than when reversed.
From this we should imagine that the device is intended for front-wheel brakes only. A shoe of ordinary construction, but shorter than usual, is anchored at one end, and a spring baud is anchored near the same spot. The operating shaft is provided with a double lever, one end of which actuates the shoe, whilst the other end operates the band. When running in the direction of the arrow the band tends to expand and so becomes self-assisting.
An adjusting screw is provided to permit of adjustment, so that equal pressure con be exerted on both shoe and band, but no compensating device is mentioned. Should this plan be applied to a clutch it is highly probable that difficulties would arise as to the balancing of the parts at high speed.
A Piston Composed of Two Metals., A PISTON composed of two metals one for resisting wear and having the same coefficient of expansion as the metal of which the cylinder is composed, and the other possessing a high degree of heat-conducting capacity, is described in specification No. 245,062, by Hans Wunderlich. The inventor points out that pistons made entirely of aluminium or similar metals have only been partially successful owing to their low resistance to wear and their coefficient of expansion being so different f r Om that of cast-iron. Be further says that such pistons owe their partial sliming to their lightness and high degree of heat con atlIctiv thitis. piston he employs a sleeve of iron and inserts the aluminium head as shown, and secures it by means of a spring disc, the edge of which, bearing against the iron and forming a gas-tight joint, allows for the uneven _ expansion of the two metals.
As shown, it would seem that the bosses of the gudgeon pin • are formed separately from the body of the piston, so that, altogether, a piston made according to this plan, would consist of no fewer than six. separate Thefts, a point which does not seem satisfactory.