Answer grounded in published legislation
Your question
On a semi trailer with double axles and gvm is less than 3499 kg, do both axles needs brakes?
The supplied extracts do not state a specific exemption or requirement based on a semi-trailer GVM below 3,499 kg. They define a semi-trailer service brake as one that brakes “the wheels thereof simultaneously,” which indicates that, where a service brake is required, it must operate on all the semi-trailer’s wheels, including both axles. 1
However, the extracts provided do not include the full regulation that determines when a semi-trailer of that mass must have a service brake. Therefore, on these sources alone, it cannot be confirmed conclusively whether both axles legally need brakes in every case. 12
Verified sources
Where this answer comes from
Road Traffic and Transport Act 22 of 1999-Regulations 2001-053
“service brake” means a brake, normally a footbrake, used in the ordinary course of events to reduce the speed of a vehicle or to stop the vehicle and which consists of - (a) a single braking system which brakes the front and rear wheels of the vehicle simultaneously or, in the case of - (i) a semi-trailer, brakes the wheels thereof simultaneously; (ii) a trailer, which according to the registration certificate thereof, was registered for the first time before 1 January 1983 and which is not a semi-trailer, brakes the front or rear wheels or all wheels thereof simultaneously; or (iii) a tractor, brakes the wheels of the rear axle or rear axle unit of the tractor simultaneously; or (b) two br...
Road Traffic and Transport Act 22 of 1999-Regulations 2001-053
(1) Subject to subregulation (4), a perso n may not operate a trailer on a public road if - (a) the mass of the trailer and any load thereon is 750 kilograms or less and - (i) does not exceed half of the tare of the drawing vehicle, unless that trailer is equipped with at least a parking brake or other device for keeping that trailer stationary; or
Road Traffic and Transport Act 22 of 1999-Regulations 2001-053
Minimum equivalent braking force in N/kg 15 20 25 30 35 12 20 29 41 55 1,95 1,95 1,95 1,95 1,95 1,95 1,95 1,95 1,95 1,95 [Tables A-D amended by GN 98/2016 to correct a typographical error which actually appeared only in Tables A and C. ] (2) Compliance with the requirements contemplated in subregulation (1)(a) and (b) is determined by - (a) actual road tests conducted on a road with a reasonably level, dry, smooth and hard surface which is free from loose material and with the stopping distance measured from the moment the particular brake is applied with the engine disengaged until the vehicle comes to rest; (b) a suitable mechanical test; or (c) both tests contemplated in paragraphs (a) an...
Road Traffic and Transport Act 22 of 1999-Regulations 2001-053
(ii) which is fitted to a breakdown vehicle, exceeds 20 400 kilograms; or (iii) which is not mentioned in subparagraphs (i) and (ii), exceeds 18 000 kilograms; (f) the axle mass load of an axle unit which consists of three axles, each of which are fitted with two or three wheels, and - [The verb “are” should be “is” to accord with the subject “each”.]
Road Traffic and Transport Act 22 of 1999-Regulations 2001-053
(1) A person may not operate on a public road any combination of motor vehicles - (a) other than a drawing vehicle and one or two trailers; (b) other than a motor vehicle drawing one other motor vehicle which is not a trailer, but in the case of an emergency service vehicle a trailer and one other vehicle may be drawn; (c) consisting of a trailer attached to a drawing vehicle in such a manner that the combination of trailer and drawing vehicle cannot bend in a horizontal plane, if the combined length of the trailer, including any drawbar or coupling and the rear overhang of the drawing vehicle exceeds three comma one metres; (d) if the length of a drawbar of any trailer in such combination,...
Road Traffic and Transport Act 22 of 1999-Regulations 2001-053
referred to in regulation 235, a rear underrun protection device which complies with the standard specification SABS I 055 “ Rear underrun protection device ” must be fitted to - (a) a trailer with a gross vehicle mass which exceeds 3 500 kilograms, first registered on or after 1 January 1988; (b) any other goods vehicle with a gross vehicle mass which exceeds 12 000 kilograms, first registered on or after 1 January 1988, but after 1 January 2002, such rear underrun protection device must be fitted to any trailer with a gross vehicle mass which exceeds 3 500 kilograms and any goods vehicle with a gross vehicle mass which exceeds 12 000 kilograms. Axle or axle unit to be fitted to semi-traile...