More Load—Less Braking Power
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I F a vehicle is carrying a greater load
than that specified by the manufacturer the maximum braking force available is materially reduced. Operators frequently buy vehicles with a rated capacity below that of the load they intend to carry and this practice can be dangerous.
This warning was given by Mr. G. R. Atkinson, senior technical officer, Ministry of Transport, West Midland Traffic area, at a meeting of the Traders' Road Transport Association, Potteries area. last week. Vehicle makers, he said, specified the highest rating compatible with safety. A typical 7-tonner, for example, was capable of carrying 10 tons, but if it were loaded to the upper limit, a high proportion of the maximum braking effort would be lost.
Mr. Atkinson referred to the opinion of many operators that hand brakes were inefficient and emphasized that adequate efficiency could be obtained by proper adjustment at suitable intervals. The hand brake had to be capable of stopping the vehicle if the foot brakes failed, and it was unlikely that there would be a relaxation of this regulation.
In a short analysis of common faults found during spot checks by M.o.T. vehicle examiners. Mr. Atkinson said that most defects affecting safety could have been rectified by careful attention to "tightening up." Careful attention to minor defects often obviated develop
ment of nfore serious faults. A complete check of all those components on a vehicle, defects in which could impair its safety on the road, normally occupied an examiner about 20-30 min.
Faults in braking systems, steering gear and suspension components were the most common causes of prohibition orders being issued by M.o.T. examiners. It was not possible to make a general statement regarding the degree of wear which could affect safety in various categories. The individual examiner was responsible for deciding the wear allowable in every case in accordance with the type of vehicle being checked by the examiner.
Although relatively few accidents were directly attributable to mechanical faults, a badly maintained vehicle was often difficult to control in an emergency. Good maintenance would, in many cases, have enabled an accident to be avoided that, in the event, was attributed to another cause.
Reverting to hand brakes, in reply to a question, Mr. Atkinson said that, in general, the foot brake system was required to give an efficiency of 50 per cent., while the hand brake was regarded as satisfactory if it afforded an efficiency of 30 per cent. Tests were normally made at 20 to 30 m.p.h. The excuse that poor braking resulted from a heavy load was not valid.