Suction-assisted Hydraulic Brakes
Page 68
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PATENT No. 694,582, comes from Girling, Ltd., Kings Road, Tyseley, Birmingham 11, and shows an improved version of a suction-assisted hydraulic brake. The chief point is that hydraulic fluid from the pedal cylinder operates the brakes directly only during the first part of the pedal movement because, as soon as the servo
cylinder comes into action, it cuts otl the fluid circuit from pedal to brakes.
The drawing shows a general arrangement in which 1 is the pedal cylinder, 2 the control valve and 3 the main hydraulic cylinder which is worked by the servo-cylinder (4). In operation, the pedal pipe is at first connected by the control valve to the main hydraulic cylinder, and thence to all the brakes; this is, of course, the usual safety, arrangement.
As soon as the main piston moves; it closes pipe 5 and any further pedal movement results only in increased pressure on a plunger in the control valve. The plunger is opposed by a diaphragm subject to the suction, so that the greater the suction the greater the braking action and the greater is the resistance felt on the pedal.
To prevent full braking power being applied when travelling backwards, the gear-lever (6) is coupled to the control valve to render the servo action inoperative when reverse gear is engaged.
In addition to the general arrangement illustrated, the patent gives detail drawings of all the main components.
EDDY-CURRENT BRAKING
AN electric brake, said to be suitable for heavy-duty work on lorries, roaches, cranes and the like, is shown A38
in patent No. 695,269, by Soc. ElectroMecanique de L'Aveyron, Rodez, France. The brake is of the eddycurrent type, which is more suitable for exerting a powerful slowing-down action than in bringing the vehicle to a standstill.
The brake consists of a disc of magnetic material which rotates between the poles of several stationary electro magnets. When these are energized, the disc acts as a short-circuited dynamo and actively resists movement.
The energy appears as heat in the disc, and an adequate air-cooling system is provided. It is important that the disc should not rub on the pole-pieces, and the patent deals with an adjustment for preventing this.
The rotor disc (1) passes between the magnet poles (not shown) and is mounted on a roller bearing fitted to a stationary axle. The bearing is not contained in the hub of the disc, but is housed in an intermediate member (2).
This is screwed into the hubs for a set distance and locked by a screwed pin (3). By removing the pin and turning the intermediate member the disc can be adjusted in an endwise sense. The locking pin can be placed in one of a number of spaced holes.
Thus it is possible to adjust the values of the air gaps between the rotor and pole pieces.
A SELF-SEALING INNER TUBE
AN inner tube which incorporates a plastic layer of soft rubber to act as a puncture seal is shown in patent No. 694,657, by the Dunlop Rubber Co., Ltd., 1, Albany Street, London, N.W.1. To reinforce the sealing compound and to prevent it being blown out, a fabric layer is also built in.
Referring to the drawing, the tube itself (1) is made of butyl rubber, and has vulcanized to the crown portion a layer (2) of rubberized nylon cord. The puncture-sealing compound is sand
wiched between the two, as shown a1 The base portion (4) is made of harder low-stretch rubber which s better resist the damaging action of tips of the cover beads.
A VEHICLE-WASHING BRUM
IT is a common practice to wad-. tall vehicle with a brush mounted the end of a long pipe so as to prov a continuous flow of water. Only th. who have used such a tool will real that the weight of 10 ft. or so of ws can add considerably to the labour. practical solution of the problem shown in patent No. 695,444 by Wood, 114, Rea Street, Birminghai
The drawing shows the head of tool, which consists of a brush an rubber protector (1). Ti 2 is made of _thin hg alloy having the minim possible weight. It d not, however, carry water; this is conveyed a much smaller tube inside, so that the act weight of water to waved about is very sm A SWISS ENGINE DISTON CO
TROLLED air-il ports are a well-knc feature of two str. engines, but patent 695,370 (La.nova A.G., Bahnhofstrass, Z 11 r i Switzerland), shows the same arrar ment applied to a four-stroke oil engparticularly the smaller high-sp types. The aim is improved scaveng of the burnt gases.
There is no inlet valve in the non sense, and during the " intake " stn a vacuum is formed in the cylinder. soon as the air ports (1) are uncove by the piston, compressed air rushem and overfills the cylinder. On the s ceeding upstroke, the air is compres into the hemispherical combust space (2), where the injector and exhaust valve (3) are located.
The power stroke is normal until air ports are uncovered a second tii when this occurs, a scavenging cha enters and blows the remaining tra of the exhaust products out via exhaust valve. An exhaust stn follows, but it expels practically cl, air.