NEW ANTI-SKID BRAKING SYSTEM
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A BRAKING system using control rA valves that react to the conditions of adhesion existing during brake application, so avoiding the possibility of any of the wheels locking, has been developed. It is known as the Kerr Anti-Skid brake and the principle behind the system is that there are various points between a tyre, its wheel and the mounting of that wheel relative to the chassis at which deflections occur during braking, and that these deflections are proportional to the adhesive forces obtaining at any time between the tyre and the ground. In practice, a hydraulic valve is inserted into the line to each wheel cylinder, and this admits fluid to the cylinder when the pedal is depressed until a certain predetermined pressure is reached, thus isolating a column of fluid under pressure in the line. At this stage external force from the suspension is applied to the valve, and the pressure is increased so long as the external force is adequate. Any decrease in the external force caused by a reduction in coefficient of friction between the tyre and the road will result in reduction of the operating pressure, irrespective of the brake-pedal loading applied. Advantages claimed for the system are that independent control of each wheel is possible; weight distribution and change of distribution during braking and cornering are taken into account; tyre wear is reduced; and maximum retardation for the prevailing conditions can be attained without locking of the wheels or loss of directional control due to braking forces. At present the system is for hydraulic brakes only, but it is suitable for commercial vehicles as well as cars, and the patents also cover a loadsensitive valve which can be incorporated to give braking effort which is proportional to axle loading. The system is being handled by Mr. W. W. Kerr, 4 Wimpole Street, London, W.1.