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GRAANGIDS
2016
GRAIN GUIDE
An example of such a calculation is:
Axle A: BA 7 000 kg
Axles B and C: 18 000 kg
Axles D, E and F: 24 000 kg
The sum of the axles and axle units is 49 000 kg.
• GCM: Regulation 239 (1) (b) is the GCM. The information appears on the information plate
mounted alongside the left front door of every vehicle. For example, GCM is 58 500 kg.
• P/D x 240: Regulation 239 (2) determines the mass permitted by the engine capacity of the ve-
hicle. This is calculated by multiplying the P/D by 240 for ordinary goods vehicles and by 400
for tractors. Example: 206 x 240 = 49 440 kg. (The tractor’s P/D must be multiplied by 400.)
• Mass of the driving axle/s x 5: Regulation 239 (3) provides that a vehicle may not be used if
the driving axle does not weigh at least a fifth of the mass of the entire vehicle. Therefore you
should make sure that the load does not rest on the other axles and the driving axle does not
bear sufficient weight. You must ensure that the vehicle has sufficient traction when climbing a
hill. The mass of the entire vehicle may therefore not be more than five times the mass of the
driving axles.
• Bridge formula: Regulation 241 (2) (e) refers to the bridge formula. The aim of this restriction is
to protect bridges. The following must be taken into account:
• You must be able to measure any group of axles.
• Axle units may not be divided for measuring purposes.
• A measurement must be made from the middle of the first axle to the middle of the last axle of
the group.
If the distance between axles A and E is 14,28 metres, it is rounded up to the next tenth of a
metre (14,30). The calculation of the bridge formula is the distance between the axles
(L) x 2 100 + 18 000 kg.
As an example: 14,30 x 2100 + 18 000 = 48 030 kg
If all five the results are compared, the results are as follows:
• Sum of the axles 49 000 kg
• GCM
58 500 kg
• P/D x 240 kg
49 440 kg
• Driving axle x 5 89 250 kg
• Bridge formula 48 030 kg
The lower of the masses is the permissible combination mass: 48 030 kg.
Proviso: If all the calculations result in a mass of more than 56 000 kg, the maximum permissible
mass is 56 000 kg. Remember that a steering axle of an articulated vehicle (horse and trailer)
must carry at least 11% of the vehicle’s mass, and other vehicles at least 20%.
For further information, contact Alta Swanepoel on 012 332 2186 or send an email to
altaswanepoel@mweb.co.za.Alta Swanepoel, Alta Swanepoel & Associates CC