EN 12642, body structure of commercial vehicles
The EN 12642 standard establishes the minimum structural strength requirements for the walls of vehicles designed for the cargo securing.
When the load is secured by general blocking, the load securing is entrusted to the vehicle structure. For example, if the load is leaning against the front wall, in the event of braking and in the absence of securing by means of web lashings, the vehicle wall must prevent the load from moving forward. In this case, if the wall does not offer sufficient resistance, the securing of the load is ineffective and, in the most serious cases, the transport unit wall can break through with the load penetrating into the passenger compartment of the vehicle.
To avoid this kind of accident, it is necessary to assess whether the structural strength of the vehicle is adequate in relation to the size of the load to be supported during transport, even in the event of emergency maneuvers.
Forces acting on the vehicle structure
As an example, we can consider the case of braking. The load tends to slide forward under the action of the inertia force Fi. Part of this force is counteracted by the frictional force Fa, but the remaining portion Fr is discharged onto the front wall, as shown in the figure.
The figure above shows the force scheme calculated according to the EN 12195-1 standard for the case of braking, with:
Friction factor: μ = 0,3
Longitudinal acceleration coefficient (braking): cx = 0,8
Therefore, the inertia force Fi = 7848 N is partially opposed by the friction force Fa = 2943 N. However, the remaining force equal to 4905 N is acting on the front wall. Will this be able to resist?
Body structure minimum requirements according to the EN 12642
The EN 12642 standard helps to answer this question. In fact it provides as a result the value of the force, expressed in daN, which the transport unit structure is able to withstand. This value must therefore be compared with the value calculated according to the EN 12195-1 standard, in order to verify the adequacy of the vehicle walls resistance required for the cargo securing.
Vehicles approved according to the EN 12642 standard can be identified by two codes:
- “L” type vehicle
- “XL” type vehicle
“XL” type vehicles offer greater walls structural strength than is guaranteed by “L” type vehicles.
The European best practices guidelines on cargo securing for road transport, in accordance with the EN 12642 standard, indicate the minimum values of structural resistance that must be guaranteed for the two types of vehicles. The force values are expressed with respect to the payload “P”, calculated as follows:
P = (gross mass – tare) x 9.81
|EN 12642 L||EN 12642 XL|
|Front wall||0,4P max. 5000 daN||0,5P|
|Rear wall||0,25P max. 3100 daN||0,3P|
|Side walls||up to 0,3P||0,4P|
For example, a vehicle with a payload of 20.000 kg, if “XL” type approved, must guarantee the following structural strength:
- Front wall: Minimum strength = 20.000 x 9.81 x 0,5 = 98.100 N = 9.810 daN
- Rear wall: Minimum strength = 20.000 x 9.81 x 0,3 = 58.860 N = 5.886 daN
- Side walls: Minimum strength = 20.000 x 9.81 x 0,4 = 78.480 N = 7.848 daN
Test for vehicles approved according to the EN 12642 standard
In order to be approved according to the EN 12642 standard, vehicles shall pass specific tests to ensure that the walls offer the structural strength required to guarantee load securing during transport.
Static tests can be performed, in which a device presses against the walls to simulate the thrust of the load, or dynamic tests, in which the loaded vehicle makes an “S” -shaped path completed by an emergency braking, as shown in the two following videos.
Marking and certification of vehicles approved accordingo to the EN 12642 standard
Per facilitare i compiti del caricatore, i veicoli omologati secondo la norma EN 12642 devono riportare in posizione ben visibile una marcatura che contenga le seguenti informazioni:
To facilitate the loader’s tasks, vehicles approved according to EN 12642 shall bear a marking in a clearly visible position containing the following information:
- Confrimation that the vehicle body structure complies with this standard
- Reference to type “L” or “XL” as relevant
- Name of manufacturer
- Year of production
A fac-simile of marking is shown below:
Furthermore, vehicles approved according to the EN 12642 standard are provided with a certificate issued by the manufacturer which, in addition to reiterating the information already shown on the label affixed, contain further specifications useful for using the vehicle in the best possible way. For example, it is specified the maximum empty space allowed between the cargo and the vehicle walls.
The certificate shall be available to the loader when designing the cargo arrangement, in order to properly exploit the load securing capabilities offered by the vehicle.
Vehicles not approved according to the EN 12642 standard
In the case of a vehicle not approved according to EN 12642, in the absence of data on the structural strength of the walls, it is not allowed to use the walls themselves as a structural element for securing the load. In this case the walls are to be regarded as a weather protection onlyconsidered as an element of protection of the load from the elements, but not as an element capable of securing the load.