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248 
ERF Brakes to Exceed C. and U. Minima
Page 76
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T°provide standards of braking exceeding the requirements of the latest C. and U. regulations, ERF Ltd. twill use actual measured stopping distance as a basis of calculating efficiency (0.5g and 0.25g minima respectively for service and emergency systems). This will have the effect of producing better results when decelerometer readings are taken.
The company has decided to use the service brake pedal to apply the emergency brakes, through an extension of pedal travel, wherever possible. To provide laden/unladen stopping in equal safety, ERF is considering the use of variable load valves.
All four-wheelers will have singlediaphragm wheel cylinders supplied through a dual-circuit brake valve to provide independant braking at both axles from separate reservoirs. Failure of any one circuit leaves the other intact, providing an efficiency of at least 0.3g. A mechanical multi-pull handbrake will be fitted for parking and gradient holding.
Six-wheelers will also use the dual brake valve system but to equalize brake distribution triple diaphragms will be fitted at the front axle; with single diaphragms on each rear axle operated separately by the halves of the dual valve, failure of any one unit still leaves braking on two axles. A single-pull handbrake with power assistance and an air release valve will be fitted, operating on the rear axles only.
An extension of the two-axle system will be used for the eight-wheelers. Each side of the dual brake valve will operate one front and one rear axle. Although at present a multi-pull mechanical handbrake is fitted, a single-pull air-assisted unit will shortly replace it.
The tractive unit axles of an articulated unit will be fitted with doublediaphragm cylinders, powered through a single valve which will also operate the trailer brakes. A single-pull handbrake will control a •rod-valve which will supply air from a separate reservoir to the secondary side of the double dia
diaphragms and, via a third line, to the double or triple diaphragm units of the trailer. Mechanical linkage for parking purposes is provided to the rear axle of the tractive unit. 'This is left applied on releasing the handbrake lever, which immediately exhausts the air pressure in the • emergency system, when the mechanical handbrake is released in the normal manner.
It will be seen that this system gives emergency braking of the same efficiency as the service brakes.