Road Traffic Regulation Act 1967

20 The conditions referred to in paragraphs 3(2) and 4(2) above are as follows:—

(a) the motor tractor, or, as the case may be, the locomotive, shall be equipped with an efficient braking system having two means of operation or with two efficient braking systems each having a separate means of operation, the system or systems being so designed and constructed that, notwithstanding the failure of any part (other than a fixed member or a brake shoe anchor pin) through or by means of which the force necessary to apply the brakes is transmitted, there is still available for application by the driver to not less than half the number of the wheels of the vehicle brakes sufficient under the most adverse conditions to bring it to rest within a reasonable distance ;

(b) the trailer shall be equipped with an efficient braking system so constructed—

(i) that when the trailer is being drawn the brakes are capable of being applied by the driver of the drawing vehicle to at least two of the wheels of a trailer having not more than four wheels and to at least four, but not less than half, of the wheels of a trailer having more than four wheels, and

(ii) that it is not rendered ineffective by the non-rotation of the engine of the drawing vehicle ;

(c) the weight transmitted to the road surface by any one wheel of the locomotive, where no other wheel is in the same line transversely, shall not exceed 4½ tons, the total weight so transmitted by any two wheels in line transversely shall not exceed 9 tons and the sum of the weights so transmitted by all the wheels shall not exceed—

(i) in the case of a vehicle having not more than four wheels, 14 tons,

(ii) in the case of a vehicle having more than four but not more than six wheels, 20 tons, and

(iii) in the case of a vehicle having more than six wheels, 24 tons;

(d) the weight transmitted by the locomotive (whether laden or unladen) to any strip of the surface of a road on which it rests contained between any two parallel lines drawn 2 feet apart on that surface at right angles to the longitudinal axis of the vehicle shall not exceed 11 tons ; and

(e) the maximum laden weight of the locomotive and trailer shall not exceed 22 tons or, if the trailer is fitted with power-assisted brakes which can be operated by the driver of the drawing vehicle and are not rendered ineffective by the non-rotation of its engine, and if that vehicle is equipped with a warning device so placed as to be readily visible to the driver when in the driving seat of the vehicle in order to indicate an impending failure or deficiency in the vacuum or pressure system, 32 tons.